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href="#overflow_establishes_a_block_formatting_context">Overflow establishes a Block Formatting Context</a></li><li class="document-toc-item "><a class="document-toc-link" href="#unwanted_overflow_in_web_design">Unwanted overflow in web design</a></li><li class="document-toc-item "><a class="document-toc-link" href="#test_your_skills!">Test your skills!</a></li><li class="document-toc-item "><a class="document-toc-link" href="#summary">Summary</a></li></ul></section></div></div><div class="sidebar-body"><ol><li class="section"><a href="/en-US/docs/Learn/Getting_started_with_the_web">Complete beginners start here!</a></li><li><details><summary>Getting started with the web</summary><ol><li><a href="/en-US/docs/Learn/Getting_started_with_the_web">Getting started with the web</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/Installing_basic_software">Installing basic software</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/What_will_your_website_look_like">What will your website look like?</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/Dealing_with_files">Dealing with files</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/HTML_basics">HTML basics</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/CSS_basics">CSS basics</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/JavaScript_basics">JavaScript basics</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/Publishing_your_website">Publishing your website</a></li><li><a href="/en-US/docs/Learn/Getting_started_with_the_web/How_the_Web_works">How the web works</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/HTML">HTML — Structuring the web</a></li><li><details><summary>Introduction to HTML</summary><ol><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML">Introduction to HTML</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Getting_started">Getting started with HTML</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/The_head_metadata_in_HTML">What's in the head? Metadata in HTML</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/HTML_text_fundamentals">HTML text fundamentals</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Creating_hyperlinks">Creating hyperlinks</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Advanced_text_formatting">Advanced text formatting</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Document_and_website_structure">Document and website structure</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Debugging_HTML">Debugging HTML</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Marking_up_a_letter">Marking up a letter</a></li><li><a href="/en-US/docs/Learn/HTML/Introduction_to_HTML/Structuring_a_page_of_content">Structuring a page of content</a></li></ol></details></li><li><details><summary>Multimedia and embedding</summary><ol><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding">Multimedia and embedding</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Images_in_HTML">Images in HTML</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Video_and_audio_content">Video and audio content</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Other_embedding_technologies">From object to iframe — other embedding technologies</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Adding_vector_graphics_to_the_Web">Adding vector graphics to the web</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Responsive_images">Responsive images</a></li><li><a href="/en-US/docs/Learn/HTML/Multimedia_and_embedding/Mozilla_splash_page">Mozilla splash page</a></li></ol></details></li><li><details><summary>HTML tables</summary><ol><li><a href="/en-US/docs/Learn/HTML/Tables">HTML tables</a></li><li><a href="/en-US/docs/Learn/HTML/Tables/Basics">HTML table basics</a></li><li><a href="/en-US/docs/Learn/HTML/Tables/Advanced">HTML table advanced features and accessibility</a></li><li><a href="/en-US/docs/Learn/HTML/Tables/Structuring_planet_data">Structuring planet data</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/CSS">CSS — Styling the web</a></li><li><details><summary>CSS first steps</summary><ol><li><a href="/en-US/docs/Learn/CSS/First_steps">CSS first steps</a></li><li><a href="/en-US/docs/Learn/CSS/First_steps/What_is_CSS">What is CSS?</a></li><li><a href="/en-US/docs/Learn/CSS/First_steps/Getting_started">Getting started with CSS</a></li><li><a href="/en-US/docs/Learn/CSS/First_steps/How_CSS_is_structured">How CSS is structured</a></li><li><a href="/en-US/docs/Learn/CSS/First_steps/How_CSS_works">How CSS works</a></li><li><a href="/en-US/docs/Learn/CSS/First_steps/Styling_a_biography_page">Styling a biography page</a></li></ol></details></li><li><details open=""><summary>CSS building blocks</summary><ol><li><a href="/en-US/docs/Learn/CSS/Building_blocks">CSS building blocks</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Selectors">CSS selectors</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Selectors/Type_Class_and_ID_Selectors">Type, class, and ID selectors</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Selectors/Attribute_selectors">Attribute selectors</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Selectors/Pseudo-classes_and_pseudo-elements">Pseudo-classes and pseudo-elements</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Selectors/Combinators">Combinators</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Cascade_and_inheritance">Cascade, specificity, and inheritance</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Cascade_layers">Cascade layers</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/The_box_model">The box model</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Backgrounds_and_borders">Backgrounds and borders</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Handling_different_text_directions">Handling different text directions</a></li><li><em><a href="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" aria-current="page">Overflowing content</a></em></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Values_and_units">CSS values and units</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Sizing_items_in_CSS">Sizing items in CSS</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Images_media_form_elements">Images, media, and form elements</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Styling_tables">Styling tables</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Advanced_styling_effects">Advanced styling effects</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Debugging_CSS">Debugging CSS</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Organizing">Organizing your CSS</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Fundamental_CSS_comprehension">Fundamental CSS comprehension</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/Creating_fancy_letterheaded_paper">Creating fancy letterheaded paper</a></li><li><a href="/en-US/docs/Learn/CSS/Building_blocks/A_cool_looking_box">A cool-looking box</a></li></ol></details></li><li><details><summary>Styling text</summary><ol><li><a href="/en-US/docs/Learn/CSS/Styling_text">CSS styling text</a></li><li><a href="/en-US/docs/Learn/CSS/Styling_text/Fundamentals">Fundamental text and font styling</a></li><li><a href="/en-US/docs/Learn/CSS/Styling_text/Styling_lists">Styling lists</a></li><li><a href="/en-US/docs/Learn/CSS/Styling_text/Styling_links">Styling links</a></li><li><a href="/en-US/docs/Learn/CSS/Styling_text/Web_fonts">Web fonts</a></li><li><a href="/en-US/docs/Learn/CSS/Styling_text/Typesetting_a_homepage">Typesetting a community school homepage</a></li></ol></details></li><li><details><summary>CSS layout</summary><ol><li><a href="/en-US/docs/Learn/CSS/CSS_layout">CSS layout</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Introduction">Introduction to CSS layout</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Normal_Flow">Normal Flow</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Flexbox">Flexbox</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Grids">Grids</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Floats">Floats</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Positioning">Positioning</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Multiple-column_Layout">Multiple-column layout</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Responsive_Design">Responsive design</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Media_queries">Beginner's guide to media queries</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Legacy_Layout_Methods">Legacy layout methods</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Supporting_Older_Browsers">Supporting older browsers</a></li><li><a href="/en-US/docs/Learn/CSS/CSS_layout/Fundamental_Layout_Comprehension">Fundamental layout comprehension</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/JavaScript">JavaScript — Dynamic client-side scripting</a></li><li><details><summary>JavaScript first steps</summary><ol><li><a href="/en-US/docs/Learn/JavaScript/First_steps">JavaScript first steps</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/What_is_JavaScript">What is JavaScript?</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/A_first_splash">A first splash into JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/What_went_wrong">What went wrong? Troubleshooting JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Variables">Storing the information you need — Variables</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Math">Basic math in JavaScript — numbers and operators</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Strings">Handling text — strings in JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Useful_string_methods">Useful string methods</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Arrays">Arrays</a></li><li><a href="/en-US/docs/Learn/JavaScript/First_steps/Silly_story_generator">Silly story generator</a></li></ol></details></li><li><details><summary>JavaScript building blocks</summary><ol><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks">JavaScript building blocks</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/conditionals">Making decisions in your code — conditionals</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Looping_code">Looping code</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Functions">Functions — reusable blocks of code</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Build_your_own_function">Build your own function</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Return_values">Function return values</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Events">Introduction to events</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Event_bubbling">Event bubbling</a></li><li><a href="/en-US/docs/Learn/JavaScript/Building_blocks/Image_gallery">Image gallery</a></li></ol></details></li><li><details><summary>Introducing JavaScript objects</summary><ol><li><a href="/en-US/docs/Learn/JavaScript/Objects">Introducing JavaScript objects</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Basics">JavaScript object basics</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Object_prototypes">Object prototypes</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Object-oriented_programming">Object-oriented programming</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Classes_in_JavaScript">Classes in JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/JSON">Working with JSON</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Object_building_practice">Object building practice</a></li><li><a href="/en-US/docs/Learn/JavaScript/Objects/Adding_bouncing_balls_features">Adding features to our bouncing balls demo</a></li></ol></details></li><li><details><summary>Asynchronous JavaScript</summary><ol><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous">Asynchronous JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous/Introducing">Introducing asynchronous JavaScript</a></li><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous/Promises">How to use promises</a></li><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous/Implementing_a_promise-based_API">How to implement a promise-based API</a></li><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous/Introducing_workers">Introducing workers</a></li><li><a href="/en-US/docs/Learn/JavaScript/Asynchronous/Sequencing_animations">Sequencing animations</a></li></ol></details></li><li><details><summary>Client-side web APIs</summary><ol><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs">Client-side web APIs</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Introduction">Introduction to web APIs</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Manipulating_documents">Manipulating documents</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Fetching_data">Fetching data from the server</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Third_party_APIs">Third-party APIs</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Drawing_graphics">Drawing graphics</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Video_and_audio_APIs">Video and Audio APIs</a></li><li><a href="/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Client-side_storage">Client-side storage</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Forms">Web forms — Working with user data</a></li><li><details><summary>Web form building blocks</summary><ol><li><a href="/en-US/docs/Learn/Forms">Web form building blocks</a></li><li><a href="/en-US/docs/Learn/Forms/Your_first_form">Your first form</a></li><li><a href="/en-US/docs/Learn/Forms/How_to_structure_a_web_form">How to structure a web form</a></li><li><a href="/en-US/docs/Learn/Forms/Basic_native_form_controls">Basic native form controls</a></li><li><a href="/en-US/docs/Learn/Forms/HTML5_input_types">The HTML5 input types</a></li><li><a href="/en-US/docs/Learn/Forms/Other_form_controls">Other form controls</a></li><li><a href="/en-US/docs/Learn/Forms/Styling_web_forms">Styling web forms</a></li><li><a href="/en-US/docs/Learn/Forms/Advanced_form_styling">Advanced form styling</a></li><li><a href="/en-US/docs/Learn/Forms/UI_pseudo-classes">UI pseudo-classes</a></li><li><a href="/en-US/docs/Learn/Forms/Form_validation">Client-side form validation</a></li><li><a href="/en-US/docs/Learn/Forms/Sending_and_retrieving_form_data">Sending form data</a></li></ol></details></li><li><details><summary>Advanced web form techniques</summary><ol><li><a href="/en-US/docs/Learn/Forms/How_to_build_custom_form_controls">How to build custom form controls</a></li><li><a href="/en-US/docs/Learn/Forms/Sending_forms_through_JavaScript">Sending forms through JavaScript</a></li><li><a href="/en-US/docs/Learn/Forms/Property_compatibility_table_for_form_controls">CSS property compatibility table for form controls</a></li><li><a href="/en-US/docs/Learn/Forms/HTML_forms_in_legacy_browsers">HTML forms in legacy browsers</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Accessibility">Accessibility — Make the web usable by everyone</a></li><li><details><summary>Accessibility guides</summary><ol><li><a href="/en-US/docs/Learn/Accessibility">Accessibility</a></li><li><a href="/en-US/docs/Learn/Accessibility/What_is_accessibility">What is accessibility?</a></li><li><a href="/en-US/docs/Learn/Accessibility/HTML">HTML: A good basis for accessibility</a></li><li><a href="/en-US/docs/Learn/Accessibility/CSS_and_JavaScript">CSS and JavaScript accessibility best practices</a></li><li><a href="/en-US/docs/Learn/Accessibility/WAI-ARIA_basics">WAI-ARIA basics</a></li><li><a href="/en-US/docs/Learn/Accessibility/Multimedia">Accessible multimedia</a></li><li><a href="/en-US/docs/Learn/Accessibility/Mobile">Mobile accessibility</a></li><li><a href="/en-US/docs/Learn/Accessibility/Accessibility_troubleshooting">Assessment: Accessibility troubleshooting</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Performance">Performance — Making websites fast and responsive</a></li><li><details><summary>Performance guides</summary><ol><li><a href="/en-US/docs/Learn/Performance">Web performance</a></li><li><a href="/en-US/docs/Learn/Performance/why_web_performance">The "why" of web performance</a></li><li><a href="/en-US/docs/Learn/Performance/What_is_web_performance">What is web performance?</a></li><li><a href="/en-US/docs/Learn/Performance/Perceived_performance">Perceived performance</a></li><li><a href="/en-US/docs/Learn/Performance/Measuring_performance">Measuring performance</a></li><li><a href="/en-US/docs/Learn/Performance/Multimedia">Multimedia: Images</a></li><li><a href="/en-US/docs/Learn/Performance/video">Multimedia: video</a></li><li><a href="/en-US/docs/Learn/Performance/JavaScript">JavaScript performance optimization</a></li><li><a href="/en-US/docs/Learn/Performance/HTML">HTML performance optimization</a></li><li><a href="/en-US/docs/Learn/Performance/CSS">CSS performance optimization</a></li><li><a href="/en-US/docs/Learn/Performance/business_case_for_performance">The business case for web performance</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/MathML">MathML — Writing mathematics with MathML</a></li><li><details><summary>MathML first steps</summary><ol><li><a href="/en-US/docs/Learn/MathML/First_steps">MathML first steps</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Getting_started">Getting started with MathML</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Text_containers">MathML Text Containers</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Fractions_and_roots">MathML fractions and roots</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Scripts">MathML scripted elements</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Tables">MathML tables</a></li><li><a href="/en-US/docs/Learn/MathML/First_steps/Three_famous_mathematical_formulas">Three famous mathematical formulas</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/../Games">Games — Developing games for the web</a></li><li><details><summary>Guides and tutorials</summary><ol><li><a href="/en-US/docs/Games/Introduction">Introduction to game development for the Web</a></li><li><a href="/en-US/docs/Games/Techniques">Techniques for game development</a></li><li><a href="/en-US/docs/Games/Tutorials">Tutorials</a></li><li><a href="/en-US/docs/Games/Publishing_games">Publishing games</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Tools_and_testing">Tools and testing</a></li><li><details><summary>Client-side web development tools</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools">Understanding client-side web development tools</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Overview">Client-side tooling overview</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Command_line">Command line crash course</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Package_management">Package management basics</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Introducing_complete_toolchain">Introducing a complete toolchain</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Deployment">Deploying our app</a></li></ol></details></li><li><details><summary>Introduction to client-side frameworks</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Introduction">Introduction to client-side frameworks</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Main_features">Framework main features</a></li></ol></details></li><li><details><summary>React</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_getting_started">Getting started with React</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_todo_list_beginning">Beginning our React todo list</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_components">Componentizing our React app</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state">React interactivity: Events and state</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_filtering_conditional_rendering">React interactivity: Editing, filtering, conditional rendering</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_accessibility">Accessibility in React</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_resources">React resources</a></li></ol></details></li><li><details><summary>Ember</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_getting_started">Getting started with Ember</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_structure_componentization">Ember app structure and componentization</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_interactivity_events_state">Ember interactivity: Events, classes and state</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_conditional_footer">Ember Interactivity: Footer functionality, conditional rendering</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_routing">Routing in Ember</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_resources">Ember resources and troubleshooting</a></li></ol></details></li><li><details><summary>Vue</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_getting_started">Getting started with Vue</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_first_component">Creating our first Vue component</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_rendering_lists">Rendering a list of Vue components</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_methods_events_models">Adding a new todo form: Vue events, methods, and models</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_styling">Styling Vue components with CSS</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_computed_properties">Using Vue computed properties</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_conditional_rendering">Vue conditional rendering: editing existing todos</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_refs_focus_management">Vue refs and lifecycle methods for focus management</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_resources">Vue resources</a></li></ol></details></li><li><details><summary>Svelte</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_getting_started">Getting started with Svelte</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_Todo_list_beginning">Starting our Svelte to-do list app</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_variables_props">Dynamic behavior in Svelte: working with variables and props</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_components">Componentizing our Svelte app</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_reactivity_lifecycle_accessibility">Advanced Svelte: Reactivity, lifecycle, accessibility</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_stores">Working with Svelte stores</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_TypeScript">TypeScript support in Svelte</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_deployment_next">Deployment and next steps</a></li></ol></details></li><li><details><summary>Angular</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_getting_started">Getting started with Angular</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_todo_list_beginning">Beginning our Angular todo list app</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_styling">Styling our Angular app</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_item_component">Creating an item component</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_filtering">Filtering our to-do items</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_building">Building Angular applications and further resources</a></li></ol></details></li><li><details><summary>Git and GitHub</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/GitHub">Git and GitHub</a></li></ol></details></li><li><details><summary>Cross browser testing</summary><ol><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing">Cross browser testing</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Introduction">Introduction to cross-browser testing</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Testing_strategies">Strategies for carrying out testing</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/HTML_and_CSS">Handling common HTML and CSS problems</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/JavaScript">Handling common JavaScript problems</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Accessibility">Handling common accessibility problems</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Feature_detection">Implementing feature detection</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Automated_testing">Introduction to automated testing</a></li><li><a href="/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Your_own_automation_environment">Setting up your own test automation environment</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Server-side">Server-side website programming</a></li><li><details><summary>First steps</summary><ol><li><a href="/en-US/docs/Learn/Server-side/First_steps">Server-side website programming first steps</a></li><li><a href="/en-US/docs/Learn/Server-side/First_steps/Introduction">Introduction to the server side</a></li><li><a href="/en-US/docs/Learn/Server-side/First_steps/Client-Server_overview">Client-Server Overview</a></li><li><a href="/en-US/docs/Learn/Server-side/First_steps/Web_frameworks">Server-side web frameworks</a></li><li><a href="/en-US/docs/Learn/Server-side/First_steps/Website_security">Website security</a></li></ol></details></li><li><details><summary>Django web framework (Python)</summary><ol><li><a href="/en-US/docs/Learn/Server-side/Django">Django Web Framework (Python)</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Introduction">Django introduction</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/development_environment">Setting up a Django development environment</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Tutorial_local_library_website">Django Tutorial: The Local Library website</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/skeleton_website">Django Tutorial Part 2: Creating a skeleton website</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Models">Django Tutorial Part 3: Using models</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Admin_site">Django Tutorial Part 4: Django admin site</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Home_page">Django Tutorial Part 5: Creating our home page</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Generic_views">Django Tutorial Part 6: Generic list and detail views</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Sessions">Django Tutorial Part 7: Sessions framework</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Authentication">Django Tutorial Part 8: User authentication and permissions</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Forms">Django Tutorial Part 9: Working with forms</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Testing">Django Tutorial Part 10: Testing a Django web application</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/Deployment">Django Tutorial Part 11: Deploying Django to production</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/web_application_security">Django web application security</a></li><li><a href="/en-US/docs/Learn/Server-side/Django/django_assessment_blog">Assessment: DIY Django mini blog</a></li></ol></details></li><li><details><summary>Express Web Framework (Node.js/JavaScript)</summary><ol><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs">Express web framework (Node.js/JavaScript)</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/Introduction">Express/Node introduction</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/development_environment">Setting up a Node development environment</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/Tutorial_local_library_website">Express Tutorial: The Local Library website</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/skeleton_website">Express Tutorial Part 2: Creating a skeleton website</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/mongoose">Express Tutorial Part 3: Using a Database (with Mongoose)</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/routes">Express Tutorial Part 4: Routes and controllers</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/Displaying_data">Express Tutorial Part 5: Displaying library data</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/forms">Express Tutorial Part 6: Working with forms</a></li><li><a href="/en-US/docs/Learn/Server-side/Express_Nodejs/deployment">Express Tutorial Part 7: Deploying to production</a></li></ol></details></li><li class="section"><a href="/en-US/docs/Learn/Common_questions">Further resources</a></li><li><details><summary>Common questions</summary><ol><li><a href="/en-US/docs/Learn/Common_questions">Common questions</a></li><li><a href="/en-US/docs/Learn/HTML/Howto">Use HTML to solve common problems</a></li><li><a href="/en-US/docs/Learn/CSS/Howto">Use CSS to solve common problems</a></li><li><a href="/en-US/docs/Learn/JavaScript/Howto">Solve common problems in your JavaScript code</a></li><li><a href="/en-US/docs/Learn/Common_questions/Web_mechanics">Web mechanics</a></li><li><a href="/en-US/docs/Learn/Common_questions/Tools_and_setup">Tools and setup</a></li><li><a href="/en-US/docs/Learn/Common_questions/Design_and_accessibility">Design and accessibility</a></li></ol></details></li></ol></div></div><section class="place side"></section></nav></aside><div class="toc-container"><aside class="toc"><nav><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In this article</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#what_is_overflow">What is overflow?</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_tries_to_avoid_data_loss">CSS tries to avoid "data loss"</a></li><li class="document-toc-item "><a class="document-toc-link" href="#the_overflow_property">The overflow property</a></li><li class="document-toc-item "><a class="document-toc-link" href="#overflow_establishes_a_block_formatting_context">Overflow establishes a Block Formatting Context</a></li><li class="document-toc-item "><a class="document-toc-link" href="#unwanted_overflow_in_web_design">Unwanted overflow in web design</a></li><li class="document-toc-item "><a class="document-toc-link" href="#test_your_skills!">Test your skills!</a></li><li class="document-toc-item "><a class="document-toc-link" href="#summary">Summary</a></li></ul></section></div></nav></aside><section class="place side"></section></div></div><main id="content" class="main-content "><article class="main-page-content" lang="en-US"><header><h1>Overflowing content</h1></header><div class="section-content"><ul class="prev-next"> <li><a class="button secondary" href="/en-US/docs/Learn/CSS/Building_blocks/Handling_different_text_directions"><span class="button-wrap"> Previous </span></a></li> <li><a class="button secondary" href="/en-US/docs/Learn/CSS/Building_blocks"><span class="button-wrap"> Overview: CSS building blocks</span></a></li> <li><a class="button secondary" href="/en-US/docs/Learn/CSS/Building_blocks/Values_and_units"><span class="button-wrap"> Next </span></a></li> </ul> <p>Overflow is what happens when there is too much content to fit in an element box. In this guide, you will learn what overflow is and how to manage it.</p> <figure class="table-container"><table> <tbody> <tr> <th scope="row">Prerequisites:</th> <td> <a href="/en-US/docs/Learn/Getting_started_with_the_web/Installing_basic_software">Basic software installed</a>, basic knowledge of <a href="/en-US/docs/Learn/Getting_started_with_the_web/Dealing_with_files">working with files</a>, HTML basics (study <a href="/en-US/docs/Learn/HTML/Introduction_to_HTML">Introduction to HTML</a>), and an idea of how CSS works (study <a href="/en-US/docs/Learn/CSS/First_steps">CSS first steps</a>.) </td> </tr> <tr> <th scope="row">Objective:</th> <td>To understand overflow and how to manage it.</td> </tr> </tbody> </table></figure></div><section aria-labelledby="what_is_overflow"><h2 id="what_is_overflow"><a href="#what_is_overflow">What is overflow?</a></h2><div class="section-content"><p>Everything in CSS is a box. You can constrain the size of these boxes by assigning values of <a href="/en-US/docs/Web/CSS/width"><code>width</code></a> and <a href="/en-US/docs/Web/CSS/height"><code>height</code></a> (or <a href="/en-US/docs/Web/CSS/inline-size"><code>inline-size</code></a> and <a href="/en-US/docs/Web/CSS/block-size"><code>block-size</code></a>). <strong>Overflow happens when there is too much content to fit in a box.</strong> CSS provides various tools to manage overflow. As you go further with CSS layout and writing CSS, you will encounter more overflow situations.</p></div></section><section aria-labelledby="css_tries_to_avoid_data_loss"><h2 id="css_tries_to_avoid_data_loss"><a href="#css_tries_to_avoid_data_loss">CSS tries to avoid "data loss"</a></h2><div class="section-content"><p>Let's consider two examples that demonstrate the default behavior of CSS when there is overflow.</p> <p>The first example is a box that has been restricted by setting a <code>height</code>. Then we add content that exceeds the allocated space. The content overflows the box and falls into the paragraph below.</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___block-overflow notranslate"><code><div class="box"> This box has a height and a width. This means that if there is too much content to be displayed within the assigned height, there will be an overflow situation. If overflow is set to hidden then any overflow will not be visible. </div> <p>This content is outside of the box.</p> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___block-overflow notranslate"><code>.box { border: 1px solid #333333; width: 250px; height: 100px; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="block-overflow sample" id="frame_block-overflow" height="200px" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="block-overflow" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>The second example is a word in a box. The box has been made too small for the word and so it breaks out of the box.</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___inline-overflow notranslate"><code><div class="word">Overflow</div> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___inline-overflow notranslate"><code>.word { border: 1px solid #333333; width: 100px; font-size: 250%; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="inline-overflow sample" id="frame_inline-overflow" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="inline-overflow" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>You might wonder why CSS works in such a messy way, displaying content outside of its intended container. Why not hide overflowing content? Why not scale the size of the container to fit all the content?</p> <p>Wherever possible, CSS does not hide content. This would cause data loss. The problem with data loss is that you might not notice. Website visitors may not notice. If the submit button on a form disappears and no one can complete the form, this could be a big problem! Instead, CSS overflows in visible ways. You are more likely to see there is a problem. At worst, a site visitor will let you know that content is overlapping.</p> <p>If you restrict a box with a <code>width</code> or a <code>height</code>, CSS trusts you to know what you are doing. CSS assumes that you are managing the potential for overflow. In general, restricting the block dimension is problematic when the box contains text. There may be more text than you expected when designing the site, or the text may be larger (for example, if the user has increased their font size).</p> <p>The next two lessons explain different approaches to control sizing in ways that are less prone to overflow. However, if you need a fixed size, you can also control how the overflow behaves. Let's read on!</p></div></section><section aria-labelledby="the_overflow_property"><h2 id="the_overflow_property"><a href="#the_overflow_property">The overflow property</a></h2><div class="section-content"><p>The <a href="/en-US/docs/Web/CSS/overflow"><code>overflow</code></a> property helps you manage an element's content overflow. Using this property, you can convey to a browser how it should handle overflow content. The default value of the <a href="/en-US/docs/Web/CSS/overflow_value"><code><overflow></code></a> value type is <code>visible</code>. With this default setting, one can see content when it overflows.</p> <p>To crop content when it overflows, you can set <code>overflow: hidden</code>. This does exactly what it says: it hides overflow. Beware that this can make some content invisible. You should only do this if hiding content won't cause problems.</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___hidden notranslate"><code><div class="box"> This box has a height and a width. This means that if there is too much content to be displayed within the assigned height, there will be an overflow situation. If overflow is set to hidden then any overflow will not be visible. </div> <p>This content is outside of the box.</p> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___hidden notranslate"><code>.box { border: 1px solid #333333; width: 250px; height: 100px; overflow: hidden; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="hidden sample" id="frame_hidden" height="200px" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="hidden" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>Instead, perhaps you would like to add scrollbars when content overflows? Using <code>overflow: scroll</code>, browsers with visible scrollbars will always display them—even if there is not enough content to overflow. This offers the advantage of keeping the layout consistent, instead of scrollbars appearing or disappearing, depending upon the amount of content in the container.</p> <p>Remove some content from the box below. Notice how the scrollbars remain, even if there is no need for scrolling:</p> <div class="notecard note"> <p> <strong>Note:</strong> Scrollbar visibility depends on the operating system. You may have to change your browser settings to always show scroll bars in order for the scroll bars to always show in the following examples. </p> </div> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___scroll notranslate"><code><div class="box"> This box has a height and a width. This means that if there is too much content to be displayed within the assigned height, there will be an overflow situation. If overflow is set to hidden then any overflow will not be visible. </div> <p>This content is outside of the box.</p> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___scroll notranslate"><code>.box { border: 1px solid #333333; width: 250px; height: 100px; overflow: scroll; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="scroll sample" id="frame_scroll" height="200px" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="scroll" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>In the example above, we only need to scroll on the <code>y</code> axis, however we get scrollbars in both axes. To just scroll on the <code>y</code> axis, you could use the <a href="/en-US/docs/Web/CSS/overflow-y"><code>overflow-y</code></a> property, setting <code>overflow-y: scroll</code>.</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___scroll-y notranslate"><code><div class="box"> This box has a height and a width. This means that if there is too much content to be displayed within the assigned height, there will be an overflow situation. If overflow is set to hidden then any overflow will not be visible. </div> <p>This content is outside of the box.</p> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___scroll-y notranslate"><code>.box { border: 1px solid #333333; width: 250px; height: 100px; overflow-y: scroll; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="scroll-y sample" id="frame_scroll-y" height="200px" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="scroll-y" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>You can also enable scrolling along the x-axis by using <a href="/en-US/docs/Web/CSS/overflow-x"><code>overflow-x</code></a>, although this is not a recommended way to accommodate long words! If you have a long word in a small box, consider using the <a href="/en-US/docs/Web/CSS/word-break"><code>word-break</code></a> or <a href="/en-US/docs/Web/CSS/overflow-wrap"><code>overflow-wrap</code></a> property. In addition, some of the methods discussed in <a href="/en-US/docs/Learn/CSS/Building_blocks/Sizing_items_in_CSS">Sizing items in CSS</a> may help you create boxes that scale better with varying amounts of content.</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___scroll-x notranslate"><code><div class="word">Overflow</div> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___scroll-x notranslate"><code>.word { border: 5px solid #333333; width: 100px; font-size: 250%; overflow-x: scroll; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="scroll-x sample" id="frame_scroll-x" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="scroll-x" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div> <p>As with <code>scroll</code>, you get a scrollbar in the scrolling dimension whether or not there is enough content to cause a scrollbar.</p> <div class="notecard note"> <p><strong>Note:</strong> You can specify x- and y-axis scrolling using the <code>overflow</code> property, passing two values. If two keywords are specified, the first applies to <code>overflow-x</code> and the second applies to <code>overflow-y</code>. Otherwise, both <code>overflow-x</code> and <code>overflow-y</code> are set to the same value. For example, <code>overflow: scroll hidden</code> would set <code>overflow-x</code> to <code>scroll</code> and <code>overflow-y</code> to <code>hidden</code>.</p> </div> <p>If you only want scrollbars to appear when there is more content than can fit in the box, use <code>overflow: auto</code>. This allows the browser to determine if it should display scrollbars.</p> <p>In the example below, remove content until it fits into the box. You should see the scrollbars disappear:</p> <div class="code-example"><div class="example-header"><span class="language-name">html</span></div><pre class="brush: html live-sample___auto notranslate"><code><div class="box"> This box has a height and a width. This means that if there is too much content to be displayed within the assigned height, there will be an overflow situation. If overflow is set to hidden then any overflow will not be visible. </div> <p>This content is outside of the box.</p> </code></pre></div> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css live-sample___auto notranslate"><code>.box { border: 1px solid #333333; width: 250px; height: 100px; overflow: auto; } </code></pre></div><div class="code-example"><div class="example-header"></div><iframe class="sample-code-frame" title="auto sample" id="frame_auto" height="200px" src="about:blank" data-live-path="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content" data-live-id="auto" sandbox="allow-same-origin allow-scripts" loading="lazy"></iframe></div></div></section><section aria-labelledby="overflow_establishes_a_block_formatting_context"><h2 id="overflow_establishes_a_block_formatting_context"><a href="#overflow_establishes_a_block_formatting_context">Overflow establishes a Block Formatting Context</a></h2><div class="section-content"><p>When you use the <code><overflow></code> values <code>scroll</code> and <code>auto</code>, you create a <a href="/en-US/docs/Web/CSS/CSS_display/Block_formatting_context"><strong>Block Formatting Context</strong> (BFC)</a>. This means that the content of an element box with these <code>overflow</code> values acquires a self-contained layout. Content outside such an element box cannot poke into the element box, and nothing from the element box can poke into the surrounding layout. This enables scrolling behavior, as all box content needs to be contained and not overlap to create a consistent scrolling experience.</p></div></section><section aria-labelledby="unwanted_overflow_in_web_design"><h2 id="unwanted_overflow_in_web_design"><a href="#unwanted_overflow_in_web_design">Unwanted overflow in web design</a></h2><div class="section-content"><p>Modern layout methods (described in <a href="/en-US/docs/Learn/CSS/CSS_layout">CSS layout</a>) manage overflow. They largely work without assumptions or dependencies for how much content there will be on a web page.</p> <p>This was not always the norm. In the past, some sites were built with fixed-height containers to align box bottoms. These boxes may otherwise have had no relationship to each other. This was fragile. If you encounter a box where content is overlaying other content on the page in legacy applications, you will now recognize that this happens with overflow. Ideally, you will refactor the layout to not rely on fixed-height containers.</p> <p>When developing a site, always keep overflow in mind. Test designs with large and small amounts of content. Increase and decrease font sizes by at least two increments. Ensure your CSS is robust. Changing overflow values to hide content or to add scrollbars is reserved for a few select use cases (for example, where you intend to have a scrolling box).</p></div></section><section aria-labelledby="test_your_skills!"><h2 id="test_your_skills!"><a href="#test_your_skills!">Test your skills!</a></h2><div class="section-content"><p>You've reached the end of this article, but can you remember the most important information? You can find some further tests to verify that you've retained this information before you move on — see <a href="/en-US/docs/Learn/CSS/Building_blocks/Overflow_Tasks">Test your skills: Overflow</a>.</p></div></section><section aria-labelledby="summary"><h2 id="summary"><a href="#summary">Summary</a></h2><div class="section-content"><p>This lesson introduced the concept of overflow. You should understand that default CSS avoids making overflowing content invisible. 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Content available under <a href="/en-US/docs/MDN/Writing_guidelines/Attrib_copyright_license">a Creative Commons license</a>.</p></div></div></footer></div><script type="application/json" id="hydration">{"url":"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"Overflowing content","mdn_url":"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content","locale":"en-US","native":"English (US)","sidebarHTML":"<ol><li class=\"section\"><a href=\"/en-US/docs/Learn/Getting_started_with_the_web\">Complete beginners start here!</a></li><li><details><summary>Getting started with the web</summary><ol><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web\">Getting started with the web</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/Installing_basic_software\">Installing basic software</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/What_will_your_website_look_like\">What will your website look like?</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/Dealing_with_files\">Dealing with files</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/HTML_basics\">HTML basics</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/CSS_basics\">CSS basics</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/JavaScript_basics\">JavaScript basics</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/Publishing_your_website\">Publishing your website</a></li><li><a href=\"/en-US/docs/Learn/Getting_started_with_the_web/How_the_Web_works\">How the web works</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/HTML\">HTML — Structuring the web</a></li><li><details><summary>Introduction to HTML</summary><ol><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML\">Introduction to HTML</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Getting_started\">Getting started with HTML</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/The_head_metadata_in_HTML\">What's in the head? Metadata in HTML</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/HTML_text_fundamentals\">HTML text fundamentals</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Creating_hyperlinks\">Creating hyperlinks</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Advanced_text_formatting\">Advanced text formatting</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Document_and_website_structure\">Document and website structure</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Debugging_HTML\">Debugging HTML</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Marking_up_a_letter\">Marking up a letter</a></li><li><a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML/Structuring_a_page_of_content\">Structuring a page of content</a></li></ol></details></li><li><details><summary>Multimedia and embedding</summary><ol><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding\">Multimedia and embedding</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Images_in_HTML\">Images in HTML</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Video_and_audio_content\">Video and audio content</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Other_embedding_technologies\">From object to iframe — other embedding technologies</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Adding_vector_graphics_to_the_Web\">Adding vector graphics to the web</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Responsive_images\">Responsive images</a></li><li><a href=\"/en-US/docs/Learn/HTML/Multimedia_and_embedding/Mozilla_splash_page\">Mozilla splash page</a></li></ol></details></li><li><details><summary>HTML tables</summary><ol><li><a href=\"/en-US/docs/Learn/HTML/Tables\">HTML tables</a></li><li><a href=\"/en-US/docs/Learn/HTML/Tables/Basics\">HTML table basics</a></li><li><a href=\"/en-US/docs/Learn/HTML/Tables/Advanced\">HTML table advanced features and accessibility</a></li><li><a href=\"/en-US/docs/Learn/HTML/Tables/Structuring_planet_data\">Structuring planet data</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/CSS\">CSS — Styling the web</a></li><li><details><summary>CSS first steps</summary><ol><li><a href=\"/en-US/docs/Learn/CSS/First_steps\">CSS first steps</a></li><li><a href=\"/en-US/docs/Learn/CSS/First_steps/What_is_CSS\">What is CSS?</a></li><li><a href=\"/en-US/docs/Learn/CSS/First_steps/Getting_started\">Getting started with CSS</a></li><li><a href=\"/en-US/docs/Learn/CSS/First_steps/How_CSS_is_structured\">How CSS is structured</a></li><li><a href=\"/en-US/docs/Learn/CSS/First_steps/How_CSS_works\">How CSS works</a></li><li><a href=\"/en-US/docs/Learn/CSS/First_steps/Styling_a_biography_page\">Styling a biography page</a></li></ol></details></li><li><details open=\"\"><summary>CSS building blocks</summary><ol><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks\">CSS building blocks</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Selectors\">CSS selectors</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Selectors/Type_Class_and_ID_Selectors\">Type, class, and ID selectors</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Selectors/Attribute_selectors\">Attribute selectors</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Selectors/Pseudo-classes_and_pseudo-elements\">Pseudo-classes and pseudo-elements</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Selectors/Combinators\">Combinators</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Cascade_and_inheritance\">Cascade, specificity, and inheritance</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Cascade_layers\">Cascade layers</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/The_box_model\">The box model</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Backgrounds_and_borders\">Backgrounds and borders</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Handling_different_text_directions\">Handling different text directions</a></li><li><em><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" aria-current=\"page\">Overflowing content</a></em></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units\">CSS values and units</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Sizing_items_in_CSS\">Sizing items in CSS</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Images_media_form_elements\">Images, media, and form elements</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Styling_tables\">Styling tables</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Advanced_styling_effects\">Advanced styling effects</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Debugging_CSS\">Debugging CSS</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Organizing\">Organizing your CSS</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Fundamental_CSS_comprehension\">Fundamental CSS comprehension</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Creating_fancy_letterheaded_paper\">Creating fancy letterheaded paper</a></li><li><a href=\"/en-US/docs/Learn/CSS/Building_blocks/A_cool_looking_box\">A cool-looking box</a></li></ol></details></li><li><details><summary>Styling text</summary><ol><li><a href=\"/en-US/docs/Learn/CSS/Styling_text\">CSS styling text</a></li><li><a href=\"/en-US/docs/Learn/CSS/Styling_text/Fundamentals\">Fundamental text and font styling</a></li><li><a href=\"/en-US/docs/Learn/CSS/Styling_text/Styling_lists\">Styling lists</a></li><li><a href=\"/en-US/docs/Learn/CSS/Styling_text/Styling_links\">Styling links</a></li><li><a href=\"/en-US/docs/Learn/CSS/Styling_text/Web_fonts\">Web fonts</a></li><li><a href=\"/en-US/docs/Learn/CSS/Styling_text/Typesetting_a_homepage\">Typesetting a community school homepage</a></li></ol></details></li><li><details><summary>CSS layout</summary><ol><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout\">CSS layout</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Introduction\">Introduction to CSS layout</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Normal_Flow\">Normal Flow</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Flexbox\">Flexbox</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Grids\">Grids</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Floats\">Floats</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Positioning\">Positioning</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Multiple-column_Layout\">Multiple-column layout</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Responsive_Design\">Responsive design</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Media_queries\">Beginner's guide to media queries</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Legacy_Layout_Methods\">Legacy layout methods</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Supporting_Older_Browsers\">Supporting older browsers</a></li><li><a href=\"/en-US/docs/Learn/CSS/CSS_layout/Fundamental_Layout_Comprehension\">Fundamental layout comprehension</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/JavaScript\">JavaScript — Dynamic client-side scripting</a></li><li><details><summary>JavaScript first steps</summary><ol><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps\">JavaScript first steps</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/What_is_JavaScript\">What is JavaScript?</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/A_first_splash\">A first splash into JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/What_went_wrong\">What went wrong? Troubleshooting JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Variables\">Storing the information you need — Variables</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Math\">Basic math in JavaScript — numbers and operators</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Strings\">Handling text — strings in JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Useful_string_methods\">Useful string methods</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Arrays\">Arrays</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/First_steps/Silly_story_generator\">Silly story generator</a></li></ol></details></li><li><details><summary>JavaScript building blocks</summary><ol><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks\">JavaScript building blocks</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/conditionals\">Making decisions in your code — conditionals</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Looping_code\">Looping code</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Functions\">Functions — reusable blocks of code</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Build_your_own_function\">Build your own function</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Return_values\">Function return values</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Events\">Introduction to events</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Event_bubbling\">Event bubbling</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Building_blocks/Image_gallery\">Image gallery</a></li></ol></details></li><li><details><summary>Introducing JavaScript objects</summary><ol><li><a href=\"/en-US/docs/Learn/JavaScript/Objects\">Introducing JavaScript objects</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Basics\">JavaScript object basics</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Object_prototypes\">Object prototypes</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Object-oriented_programming\">Object-oriented programming</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Classes_in_JavaScript\">Classes in JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/JSON\">Working with JSON</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Object_building_practice\">Object building practice</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Objects/Adding_bouncing_balls_features\">Adding features to our bouncing balls demo</a></li></ol></details></li><li><details><summary>Asynchronous JavaScript</summary><ol><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous\">Asynchronous JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous/Introducing\">Introducing asynchronous JavaScript</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous/Promises\">How to use promises</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous/Implementing_a_promise-based_API\">How to implement a promise-based API</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous/Introducing_workers\">Introducing workers</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Asynchronous/Sequencing_animations\">Sequencing animations</a></li></ol></details></li><li><details><summary>Client-side web APIs</summary><ol><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs\">Client-side web APIs</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Introduction\">Introduction to web APIs</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Manipulating_documents\">Manipulating documents</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Fetching_data\">Fetching data from the server</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Third_party_APIs\">Third-party APIs</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Drawing_graphics\">Drawing graphics</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Video_and_audio_APIs\">Video and Audio APIs</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Client-side_web_APIs/Client-side_storage\">Client-side storage</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Forms\">Web forms — Working with user data</a></li><li><details><summary>Web form building blocks</summary><ol><li><a href=\"/en-US/docs/Learn/Forms\">Web form building blocks</a></li><li><a href=\"/en-US/docs/Learn/Forms/Your_first_form\">Your first form</a></li><li><a href=\"/en-US/docs/Learn/Forms/How_to_structure_a_web_form\">How to structure a web form</a></li><li><a href=\"/en-US/docs/Learn/Forms/Basic_native_form_controls\">Basic native form controls</a></li><li><a href=\"/en-US/docs/Learn/Forms/HTML5_input_types\">The HTML5 input types</a></li><li><a href=\"/en-US/docs/Learn/Forms/Other_form_controls\">Other form controls</a></li><li><a href=\"/en-US/docs/Learn/Forms/Styling_web_forms\">Styling web forms</a></li><li><a href=\"/en-US/docs/Learn/Forms/Advanced_form_styling\">Advanced form styling</a></li><li><a href=\"/en-US/docs/Learn/Forms/UI_pseudo-classes\">UI pseudo-classes</a></li><li><a href=\"/en-US/docs/Learn/Forms/Form_validation\">Client-side form validation</a></li><li><a href=\"/en-US/docs/Learn/Forms/Sending_and_retrieving_form_data\">Sending form data</a></li></ol></details></li><li><details><summary>Advanced web form techniques</summary><ol><li><a href=\"/en-US/docs/Learn/Forms/How_to_build_custom_form_controls\">How to build custom form controls</a></li><li><a href=\"/en-US/docs/Learn/Forms/Sending_forms_through_JavaScript\">Sending forms through JavaScript</a></li><li><a href=\"/en-US/docs/Learn/Forms/Property_compatibility_table_for_form_controls\">CSS property compatibility table for form controls</a></li><li><a href=\"/en-US/docs/Learn/Forms/HTML_forms_in_legacy_browsers\">HTML forms in legacy browsers</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Accessibility\">Accessibility — Make the web usable by everyone</a></li><li><details><summary>Accessibility guides</summary><ol><li><a href=\"/en-US/docs/Learn/Accessibility\">Accessibility</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/What_is_accessibility\">What is accessibility?</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/HTML\">HTML: A good basis for accessibility</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/CSS_and_JavaScript\">CSS and JavaScript accessibility best practices</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/WAI-ARIA_basics\">WAI-ARIA basics</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/Multimedia\">Accessible multimedia</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/Mobile\">Mobile accessibility</a></li><li><a href=\"/en-US/docs/Learn/Accessibility/Accessibility_troubleshooting\">Assessment: Accessibility troubleshooting</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Performance\">Performance — Making websites fast and responsive</a></li><li><details><summary>Performance guides</summary><ol><li><a href=\"/en-US/docs/Learn/Performance\">Web performance</a></li><li><a href=\"/en-US/docs/Learn/Performance/why_web_performance\">The \"why\" of web performance</a></li><li><a href=\"/en-US/docs/Learn/Performance/What_is_web_performance\">What is web performance?</a></li><li><a href=\"/en-US/docs/Learn/Performance/Perceived_performance\">Perceived performance</a></li><li><a href=\"/en-US/docs/Learn/Performance/Measuring_performance\">Measuring performance</a></li><li><a href=\"/en-US/docs/Learn/Performance/Multimedia\">Multimedia: Images</a></li><li><a href=\"/en-US/docs/Learn/Performance/video\">Multimedia: video</a></li><li><a href=\"/en-US/docs/Learn/Performance/JavaScript\">JavaScript performance optimization</a></li><li><a href=\"/en-US/docs/Learn/Performance/HTML\">HTML performance optimization</a></li><li><a href=\"/en-US/docs/Learn/Performance/CSS\">CSS performance optimization</a></li><li><a href=\"/en-US/docs/Learn/Performance/business_case_for_performance\">The business case for web performance</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/MathML\">MathML — Writing mathematics with MathML</a></li><li><details><summary>MathML first steps</summary><ol><li><a href=\"/en-US/docs/Learn/MathML/First_steps\">MathML first steps</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Getting_started\">Getting started with MathML</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Text_containers\">MathML Text Containers</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Fractions_and_roots\">MathML fractions and roots</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Scripts\">MathML scripted elements</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Tables\">MathML tables</a></li><li><a href=\"/en-US/docs/Learn/MathML/First_steps/Three_famous_mathematical_formulas\">Three famous mathematical formulas</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/../Games\">Games — Developing games for the web</a></li><li><details><summary>Guides and tutorials</summary><ol><li><a href=\"/en-US/docs/Games/Introduction\">Introduction to game development for the Web</a></li><li><a href=\"/en-US/docs/Games/Techniques\">Techniques for game development</a></li><li><a href=\"/en-US/docs/Games/Tutorials\">Tutorials</a></li><li><a href=\"/en-US/docs/Games/Publishing_games\">Publishing games</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Tools_and_testing\">Tools and testing</a></li><li><details><summary>Client-side web development tools</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools\">Understanding client-side web development tools</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Overview\">Client-side tooling overview</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Command_line\">Command line crash course</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Package_management\">Package management basics</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Introducing_complete_toolchain\">Introducing a complete toolchain</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Understanding_client-side_tools/Deployment\">Deploying our app</a></li></ol></details></li><li><details><summary>Introduction to client-side frameworks</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Introduction\">Introduction to client-side frameworks</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Main_features\">Framework main features</a></li></ol></details></li><li><details><summary>React</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_getting_started\">Getting started with React</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_todo_list_beginning\">Beginning our React todo list</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_components\">Componentizing our React app</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_events_state\">React interactivity: Events and state</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_interactivity_filtering_conditional_rendering\">React interactivity: Editing, filtering, conditional rendering</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_accessibility\">Accessibility in React</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_resources\">React resources</a></li></ol></details></li><li><details><summary>Ember</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_getting_started\">Getting started with Ember</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_structure_componentization\">Ember app structure and componentization</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_interactivity_events_state\">Ember interactivity: Events, classes and state</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_conditional_footer\">Ember Interactivity: Footer functionality, conditional rendering</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_routing\">Routing in Ember</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Ember_resources\">Ember resources and troubleshooting</a></li></ol></details></li><li><details><summary>Vue</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_getting_started\">Getting started with Vue</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_first_component\">Creating our first Vue component</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_rendering_lists\">Rendering a list of Vue components</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_methods_events_models\">Adding a new todo form: Vue events, methods, and models</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_styling\">Styling Vue components with CSS</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_computed_properties\">Using Vue computed properties</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_conditional_rendering\">Vue conditional rendering: editing existing todos</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_refs_focus_management\">Vue refs and lifecycle methods for focus management</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_resources\">Vue resources</a></li></ol></details></li><li><details><summary>Svelte</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_getting_started\">Getting started with Svelte</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_Todo_list_beginning\">Starting our Svelte to-do list app</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_variables_props\">Dynamic behavior in Svelte: working with variables and props</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_components\">Componentizing our Svelte app</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_reactivity_lifecycle_accessibility\">Advanced Svelte: Reactivity, lifecycle, accessibility</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_stores\">Working with Svelte stores</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_TypeScript\">TypeScript support in Svelte</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Svelte_deployment_next\">Deployment and next steps</a></li></ol></details></li><li><details><summary>Angular</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_getting_started\">Getting started with Angular</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_todo_list_beginning\">Beginning our Angular todo list app</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_styling\">Styling our Angular app</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_item_component\">Creating an item component</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_filtering\">Filtering our to-do items</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Angular_building\">Building Angular applications and further resources</a></li></ol></details></li><li><details><summary>Git and GitHub</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/GitHub\">Git and GitHub</a></li></ol></details></li><li><details><summary>Cross browser testing</summary><ol><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing\">Cross browser testing</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Introduction\">Introduction to cross-browser testing</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Testing_strategies\">Strategies for carrying out testing</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/HTML_and_CSS\">Handling common HTML and CSS problems</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/JavaScript\">Handling common JavaScript problems</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Accessibility\">Handling common accessibility problems</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Feature_detection\">Implementing feature detection</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Automated_testing\">Introduction to automated testing</a></li><li><a href=\"/en-US/docs/Learn/Tools_and_testing/Cross_browser_testing/Your_own_automation_environment\">Setting up your own test automation environment</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Server-side\">Server-side website programming</a></li><li><details><summary>First steps</summary><ol><li><a href=\"/en-US/docs/Learn/Server-side/First_steps\">Server-side website programming first steps</a></li><li><a href=\"/en-US/docs/Learn/Server-side/First_steps/Introduction\">Introduction to the server side</a></li><li><a href=\"/en-US/docs/Learn/Server-side/First_steps/Client-Server_overview\">Client-Server Overview</a></li><li><a href=\"/en-US/docs/Learn/Server-side/First_steps/Web_frameworks\">Server-side web frameworks</a></li><li><a href=\"/en-US/docs/Learn/Server-side/First_steps/Website_security\">Website security</a></li></ol></details></li><li><details><summary>Django web framework (Python)</summary><ol><li><a href=\"/en-US/docs/Learn/Server-side/Django\">Django Web Framework (Python)</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Introduction\">Django introduction</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/development_environment\">Setting up a Django development environment</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Tutorial_local_library_website\">Django Tutorial: The Local Library website</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/skeleton_website\">Django Tutorial Part 2: Creating a skeleton website</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Models\">Django Tutorial Part 3: Using models</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Admin_site\">Django Tutorial Part 4: Django admin site</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Home_page\">Django Tutorial Part 5: Creating our home page</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Generic_views\">Django Tutorial Part 6: Generic list and detail views</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Sessions\">Django Tutorial Part 7: Sessions framework</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Authentication\">Django Tutorial Part 8: User authentication and permissions</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Forms\">Django Tutorial Part 9: Working with forms</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Testing\">Django Tutorial Part 10: Testing a Django web application</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/Deployment\">Django Tutorial Part 11: Deploying Django to production</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/web_application_security\">Django web application security</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Django/django_assessment_blog\">Assessment: DIY Django mini blog</a></li></ol></details></li><li><details><summary>Express Web Framework (Node.js/JavaScript)</summary><ol><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs\">Express web framework (Node.js/JavaScript)</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/Introduction\">Express/Node introduction</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/development_environment\">Setting up a Node development environment</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/Tutorial_local_library_website\">Express Tutorial: The Local Library website</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/skeleton_website\">Express Tutorial Part 2: Creating a skeleton website</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/mongoose\">Express Tutorial Part 3: Using a Database (with Mongoose)</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/routes\">Express Tutorial Part 4: Routes and controllers</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/Displaying_data\">Express Tutorial Part 5: Displaying library data</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/forms\">Express Tutorial Part 6: Working with forms</a></li><li><a href=\"/en-US/docs/Learn/Server-side/Express_Nodejs/deployment\">Express Tutorial Part 7: Deploying to production</a></li></ol></details></li><li class=\"section\"><a href=\"/en-US/docs/Learn/Common_questions\">Further resources</a></li><li><details><summary>Common questions</summary><ol><li><a href=\"/en-US/docs/Learn/Common_questions\">Common questions</a></li><li><a href=\"/en-US/docs/Learn/HTML/Howto\">Use HTML to solve common problems</a></li><li><a href=\"/en-US/docs/Learn/CSS/Howto\">Use CSS to solve common problems</a></li><li><a href=\"/en-US/docs/Learn/JavaScript/Howto\">Solve common problems in your JavaScript code</a></li><li><a href=\"/en-US/docs/Learn/Common_questions/Web_mechanics\">Web mechanics</a></li><li><a href=\"/en-US/docs/Learn/Common_questions/Tools_and_setup\">Tools and setup</a></li><li><a href=\"/en-US/docs/Learn/Common_questions/Design_and_accessibility\">Design and accessibility</a></li></ol></details></li></ol>","sidebarMacro":"LearnSidebar","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<ul class=\"prev-next\">\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks/Handling_different_text_directions\"><span class=\"button-wrap\"> Previous </span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks\"><span class=\"button-wrap\"> Overview: CSS building blocks</span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units\"><span class=\"button-wrap\"> Next </span></a></li>\n</ul>\n<p>Overflow is what happens when there is too much content to fit in an element box. In this guide, you will learn what overflow is and how to manage it.</p>\n<figure class=\"table-container\"><table>\n <tbody>\n <tr>\n <th scope=\"row\">Prerequisites:</th>\n <td>\n <a href=\"/en-US/docs/Learn/Getting_started_with_the_web/Installing_basic_software\">Basic software installed</a>, basic knowledge of\n <a href=\"/en-US/docs/Learn/Getting_started_with_the_web/Dealing_with_files\">working with files</a>, HTML basics (study\n <a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML\">Introduction to HTML</a>), and an idea of how CSS works (study\n <a href=\"/en-US/docs/Learn/CSS/First_steps\">CSS first steps</a>.)\n </td>\n </tr>\n <tr>\n <th scope=\"row\">Objective:</th>\n <td>To understand overflow and how to manage it.</td>\n </tr>\n </tbody>\n</table></figure>"}},{"type":"prose","value":{"id":"what_is_overflow","title":"What is overflow?","isH3":false,"content":"<p>Everything in CSS is a box. You can constrain the size of these boxes by assigning values of <a href=\"/en-US/docs/Web/CSS/width\"><code>width</code></a> and <a href=\"/en-US/docs/Web/CSS/height\"><code>height</code></a> (or <a href=\"/en-US/docs/Web/CSS/inline-size\"><code>inline-size</code></a> and <a href=\"/en-US/docs/Web/CSS/block-size\"><code>block-size</code></a>). <strong>Overflow happens when there is too much content to fit in a box.</strong> CSS provides various tools to manage overflow. As you go further with CSS layout and writing CSS, you will encounter more overflow situations.</p>"}},{"type":"prose","value":{"id":"css_tries_to_avoid_data_loss","title":"CSS tries to avoid \"data loss\"","isH3":false,"content":"<p>Let's consider two examples that demonstrate the default behavior of CSS when there is overflow.</p>\n<p>The first example is a box that has been restricted by setting a <code>height</code>. Then we add content that exceeds the allocated space. The content overflows the box and falls into the paragraph below.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___block-overflow notranslate\"><code><div class=\"box\">\n This box has a height and a width. This means that if there is too much\n content to be displayed within the assigned height, there will be an overflow\n situation. If overflow is set to hidden then any overflow will not be visible.\n</div>\n\n<p>This content is outside of the box.</p>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___block-overflow notranslate\"><code>.box {\n border: 1px solid #333333;\n width: 250px;\n height: 100px;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"block-overflow sample\" id=\"frame_block-overflow\" height=\"200px\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"block-overflow\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>The second example is a word in a box. The box has been made too small for the word and so it breaks out of the box.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___inline-overflow notranslate\"><code><div class=\"word\">Overflow</div>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___inline-overflow notranslate\"><code>.word {\n border: 1px solid #333333;\n width: 100px;\n font-size: 250%;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"inline-overflow sample\" id=\"frame_inline-overflow\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"inline-overflow\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>You might wonder why CSS works in such a messy way, displaying content outside of its intended container. Why not hide overflowing content? Why not scale the size of the container to fit all the content?</p>\n<p>Wherever possible, CSS does not hide content. This would cause data loss. The problem with data loss is that you might not notice. Website visitors may not notice. If the submit button on a form disappears and no one can complete the form, this could be a big problem! Instead, CSS overflows in visible ways. You are more likely to see there is a problem. At worst, a site visitor will let you know that content is overlapping.</p>\n<p>If you restrict a box with a <code>width</code> or a <code>height</code>, CSS trusts you to know what you are doing. CSS assumes that you are managing the potential for overflow. In general, restricting the block dimension is problematic when the box contains text. There may be more text than you expected when designing the site, or the text may be larger (for example, if the user has increased their font size).</p>\n<p>The next two lessons explain different approaches to control sizing in ways that are less prone to overflow. However, if you need a fixed size, you can also control how the overflow behaves. Let's read on!</p>"}},{"type":"prose","value":{"id":"the_overflow_property","title":"The overflow property","isH3":false,"content":"<p>The <a href=\"/en-US/docs/Web/CSS/overflow\"><code>overflow</code></a> property helps you manage an element's content overflow. Using this property, you can convey to a browser how it should handle overflow content. The default value of the <a href=\"/en-US/docs/Web/CSS/overflow_value\"><code><overflow></code></a> value type is <code>visible</code>. With this default setting, one can see content when it overflows.</p>\n<p>To crop content when it overflows, you can set <code>overflow: hidden</code>. This does exactly what it says: it hides overflow. Beware that this can make some content invisible. You should only do this if hiding content won't cause problems.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___hidden notranslate\"><code><div class=\"box\">\n This box has a height and a width. This means that if there is too much\n content to be displayed within the assigned height, there will be an overflow\n situation. If overflow is set to hidden then any overflow will not be visible.\n</div>\n\n<p>This content is outside of the box.</p>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___hidden notranslate\"><code>.box {\n border: 1px solid #333333;\n width: 250px;\n height: 100px;\n overflow: hidden;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"hidden sample\" id=\"frame_hidden\" height=\"200px\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"hidden\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>Instead, perhaps you would like to add scrollbars when content overflows? Using <code>overflow: scroll</code>, browsers with visible scrollbars will always display them—even if there is not enough content to overflow. This offers the advantage of keeping the layout consistent, instead of scrollbars appearing or disappearing, depending upon the amount of content in the container.</p>\n<p>Remove some content from the box below. Notice how the scrollbars remain, even if there is no need for scrolling:</p>\n<div class=\"notecard note\">\n <p>\n <strong>Note:</strong> Scrollbar visibility depends on the operating system.\n You may have to change your browser settings to always show scroll bars in order for the scroll bars to always show in the following examples.\n </p>\n</div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___scroll notranslate\"><code><div class=\"box\">\n This box has a height and a width. This means that if there is too much\n content to be displayed within the assigned height, there will be an overflow\n situation. If overflow is set to hidden then any overflow will not be visible.\n</div>\n\n<p>This content is outside of the box.</p>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___scroll notranslate\"><code>.box {\n border: 1px solid #333333;\n width: 250px;\n height: 100px;\n overflow: scroll;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"scroll sample\" id=\"frame_scroll\" height=\"200px\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"scroll\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>In the example above, we only need to scroll on the <code>y</code> axis, however we get scrollbars in both axes. To just scroll on the <code>y</code> axis, you could use the <a href=\"/en-US/docs/Web/CSS/overflow-y\"><code>overflow-y</code></a> property, setting <code>overflow-y: scroll</code>.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___scroll-y notranslate\"><code><div class=\"box\">\n This box has a height and a width. This means that if there is too much\n content to be displayed within the assigned height, there will be an overflow\n situation. If overflow is set to hidden then any overflow will not be visible.\n</div>\n\n<p>This content is outside of the box.</p>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___scroll-y notranslate\"><code>.box {\n border: 1px solid #333333;\n width: 250px;\n height: 100px;\n overflow-y: scroll;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"scroll-y sample\" id=\"frame_scroll-y\" height=\"200px\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"scroll-y\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>You can also enable scrolling along the x-axis by using <a href=\"/en-US/docs/Web/CSS/overflow-x\"><code>overflow-x</code></a>, although this is not a recommended way to accommodate long words! If you have a long word in a small box, consider using the <a href=\"/en-US/docs/Web/CSS/word-break\"><code>word-break</code></a> or <a href=\"/en-US/docs/Web/CSS/overflow-wrap\"><code>overflow-wrap</code></a> property. In addition, some of the methods discussed in <a href=\"/en-US/docs/Learn/CSS/Building_blocks/Sizing_items_in_CSS\">Sizing items in CSS</a> may help you create boxes that scale better with varying amounts of content.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___scroll-x notranslate\"><code><div class=\"word\">Overflow</div>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___scroll-x notranslate\"><code>.word {\n border: 5px solid #333333;\n width: 100px;\n font-size: 250%;\n overflow-x: scroll;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"scroll-x sample\" id=\"frame_scroll-x\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"scroll-x\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>\n<p>As with <code>scroll</code>, you get a scrollbar in the scrolling dimension whether or not there is enough content to cause a scrollbar.</p>\n<div class=\"notecard note\">\n <p><strong>Note:</strong> You can specify x- and y-axis scrolling using the <code>overflow</code> property, passing two values. If two keywords are specified, the first applies to <code>overflow-x</code> and the second applies to <code>overflow-y</code>. Otherwise, both <code>overflow-x</code> and <code>overflow-y</code> are set to the same value. For example, <code>overflow: scroll hidden</code> would set <code>overflow-x</code> to <code>scroll</code> and <code>overflow-y</code> to <code>hidden</code>.</p>\n</div>\n<p>If you only want scrollbars to appear when there is more content than can fit in the box, use <code>overflow: auto</code>. This allows the browser to determine if it should display scrollbars.</p>\n<p>In the example below, remove content until it fits into the box. You should see the scrollbars disappear:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">html</span></div><pre class=\"brush: html live-sample___auto notranslate\"><code><div class=\"box\">\n This box has a height and a width. This means that if there is too much\n content to be displayed within the assigned height, there will be an overflow\n situation. If overflow is set to hidden then any overflow will not be visible.\n</div>\n\n<p>This content is outside of the box.</p>\n</code></pre></div>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css live-sample___auto notranslate\"><code>.box {\n border: 1px solid #333333;\n width: 250px;\n height: 100px;\n overflow: auto;\n}\n</code></pre></div><div class=\"code-example\"><div class=\"example-header\"></div><iframe class=\"sample-code-frame\" title=\"auto sample\" id=\"frame_auto\" height=\"200px\" src=\"about:blank\" data-live-path=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\" data-live-id=\"auto\" sandbox=\"allow-same-origin allow-scripts\" loading=\"lazy\"></iframe></div>"}},{"type":"prose","value":{"id":"overflow_establishes_a_block_formatting_context","title":"Overflow establishes a Block Formatting Context","isH3":false,"content":"<p>When you use the <code><overflow></code> values <code>scroll</code> and <code>auto</code>, you create a <a href=\"/en-US/docs/Web/CSS/CSS_display/Block_formatting_context\"><strong>Block Formatting Context</strong> (BFC)</a>. This means that the content of an element box with these <code>overflow</code> values acquires a self-contained layout. Content outside such an element box cannot poke into the element box, and nothing from the element box can poke into the surrounding layout. This enables scrolling behavior, as all box content needs to be contained and not overlap to create a consistent scrolling experience.</p>"}},{"type":"prose","value":{"id":"unwanted_overflow_in_web_design","title":"Unwanted overflow in web design","isH3":false,"content":"<p>Modern layout methods (described in <a href=\"/en-US/docs/Learn/CSS/CSS_layout\">CSS layout</a>) manage overflow. They largely work without assumptions or dependencies for how much content there will be on a web page.</p>\n<p>This was not always the norm. In the past, some sites were built with fixed-height containers to align box bottoms. These boxes may otherwise have had no relationship to each other. This was fragile. If you encounter a box where content is overlaying other content on the page in legacy applications, you will now recognize that this happens with overflow. Ideally, you will refactor the layout to not rely on fixed-height containers.</p>\n<p>When developing a site, always keep overflow in mind. Test designs with large and small amounts of content. Increase and decrease font sizes by at least two increments. Ensure your CSS is robust. Changing overflow values to hide content or to add scrollbars is reserved for a few select use cases (for example, where you intend to have a scrolling box).</p>"}},{"type":"prose","value":{"id":"test_your_skills!","title":"Test your skills!","isH3":false,"content":"<p>You've reached the end of this article, but can you remember the most important information? You can find some further tests to verify that you've retained this information before you move on — see <a href=\"/en-US/docs/Learn/CSS/Building_blocks/Overflow_Tasks\">Test your skills: Overflow</a>.</p>"}},{"type":"prose","value":{"id":"summary","title":"Summary","isH3":false,"content":"<p>This lesson introduced the concept of overflow. You should understand that default CSS avoids making overflowing content invisible. You have discovered that you can manage potential overflow, and also, that you should test work to make sure it does not accidentally cause problematic overflow.</p>\n<p>In the next article, we'll take a look at the most common <a href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units\">values and units</a> in CSS.</p><ul class=\"prev-next\">\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks/Handling_different_text_directions\"><span class=\"button-wrap\"> Previous </span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks\"><span class=\"button-wrap\"> Overview: CSS building blocks</span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units\"><span class=\"button-wrap\"> Next </span></a></li>\n</ul>"}}],"toc":[{"text":"What is overflow?","id":"what_is_overflow"},{"text":"CSS tries to avoid \"data loss\"","id":"css_tries_to_avoid_data_loss"},{"text":"The overflow property","id":"the_overflow_property"},{"text":"Overflow establishes a Block Formatting Context","id":"overflow_establishes_a_block_formatting_context"},{"text":"Unwanted overflow in web design","id":"unwanted_overflow_in_web_design"},{"text":"Test your skills!","id":"test_your_skills!"},{"text":"Summary","id":"summary"}],"summary":"This lesson introduced the concept of overflow. You should understand that default CSS avoids making overflowing content invisible. You have discovered that you can manage potential overflow, and also, that you should test work to make sure it does not accidentally cause problematic overflow.","popularity":0.0372,"modified":"2024-11-02T12:23:52.000Z","other_translations":[{"locale":"de","title":"Überlaufender Inhalt","native":"Deutsch"},{"locale":"es","title":"Contenido desbordado","native":"Español"},{"locale":"fr","title":"Débordements de contenu (overflow)","native":"Français"},{"locale":"ja","title":"要素のオーバーフロー","native":"日本語"},{"locale":"ko","title":"콘텐츠 overflow","native":"한국어"},{"locale":"ru","title":"Переполнение содержимого","native":"Русский"},{"locale":"zh-CN","title":"溢出的内容","native":"中文 (简体)"}],"pageType":"learn-module-chapter","source":{"folder":"en-us/learn/css/building_blocks/overflowing_content","github_url":"https://github.com/mdn/content/blob/main/files/en-us/learn/css/building_blocks/overflowing_content/index.md","last_commit_url":"https://github.com/mdn/content/commit/68772e87a84d6d6fc6a8e377dea4998afbeb511c","filename":"index.md"},"short_title":"Overflowing content","parents":[{"uri":"/en-US/docs/Learn","title":"Guides"},{"uri":"/en-US/docs/Learn/CSS","title":"CSS"},{"uri":"/en-US/docs/Learn/CSS/Building_blocks","title":"CSS building blocks"},{"uri":"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content","title":"Overflowing content"}],"pageTitle":"Overflowing content - Learn web development | MDN","noIndexing":false}}</script></body></html>