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id="sidebar-filter-label" class="sidebar-filter-label" for="sidebar-filter-input"><span class="icon icon-filter"></span><span class="visually-hidden">Filter sidebar</span></label><input id="sidebar-filter-input" autoComplete="off" class="sidebar-filter-input-field false" type="text" placeholder="Filter" value=""/><button type="button" class="button action has-icon clear-sidebar-filter-button"><span class="button-wrap"><span class="icon icon-cancel "></span><span class="visually-hidden">Clear filter input</span></span></button></div></section></header><div class="sidebar-inner-nav"><div class="in-nav-toc"><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_css_for">What is CSS for?</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_syntax">CSS syntax</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_modules">CSS modules</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_specifications">CSS specifications</a></li><li class="document-toc-item "><a class="document-toc-link" href="#browser_support_information">Browser support information</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 open=""><summary>CSS first steps</summary><ol><li><a href="/en-US/docs/Learn/CSS/First_steps">CSS first steps</a></li><li><em><a href="/en-US/docs/Learn/CSS/First_steps/What_is_CSS" aria-current="page">What is CSS?</a></em></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><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><a href="/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content">Overflowing content</a></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_css_for">What is CSS for?</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_syntax">CSS syntax</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_modules">CSS modules</a></li><li class="document-toc-item "><a class="document-toc-link" href="#css_specifications">CSS specifications</a></li><li class="document-toc-item "><a class="document-toc-link" href="#browser_support_information">Browser support information</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>What is CSS?</h1></header><div class="section-content"><ul class="prev-next"> <li><a class="button secondary" href="/en-US/docs/Learn/CSS/First_steps"><span class="button-wrap"> Overview: CSS first steps</span></a></li> <li><a class="button secondary" href="/en-US/docs/Learn/CSS/First_steps/Getting_started"><span class="button-wrap"> Next </span></a></li> </ul> <p><strong><a href="/en-US/docs/Glossary/CSS">CSS</a></strong> (Cascading Style Sheets) allows you to create great-looking web pages, but how does it work under the hood? This article explains what CSS is with a simple syntax example and also covers some key terms about the language.</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>, and HTML basics (study <a href="/en-US/docs/Learn/HTML/Introduction_to_HTML">Introduction to HTML</a>.) </td> </tr> <tr> <th scope="row">Objective:</th> <td>To learn what CSS is.</td> </tr> </tbody> </table></figure> <p>In the <a href="/en-US/docs/Learn/HTML/Introduction_to_HTML">Introduction to HTML</a> module, we covered what HTML is and how it is used to mark up documents. These documents will be readable in a web browser. Headings will look larger than regular text, paragraphs break onto a new line and have space between them. Links are colored and underlined to distinguish them from the rest of the text. What you are seeing are the browser's default styles — very basic styles — that the browser applies to HTML to make sure that the page will be basically readable even if no explicit styling is specified by the author of the page.</p> <p> <img src="/en-US/docs/Learn/CSS/First_steps/What_is_CSS/html-example.png" alt="The default styles used by a browser" width="1385" height="594" loading="lazy"> </p> <p>However, the web would be a boring place if all websites looked like that. Using CSS, you can control exactly how HTML elements look in the browser, presenting your markup using whatever design you like.</p> <p>For more on browser/default styles, check out the following video:</p><iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/spK_S0HfzFw" title="YouTube video" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen="" loading="lazy"></iframe></div><section aria-labelledby="what_is_css_for"><h2 id="what_is_css_for"><a href="#what_is_css_for">What is CSS for?</a></h2><div class="section-content"><p>As we have mentioned before, CSS is a language for specifying how documents are presented to users — how they are styled, laid out, etc.</p> <p>A <strong>document</strong> is usually a text file structured using a markup language — <a href="/en-US/docs/Glossary/HTML">HTML</a> is the most common markup language, but you may also come across other markup languages such as <a href="/en-US/docs/Glossary/SVG">SVG</a> or <a href="/en-US/docs/Glossary/XML">XML</a>.</p> <p><strong>Presenting</strong> a document to a user means converting it into a form usable by your audience. <a href="/en-US/docs/Glossary/Browser">Browsers</a>, like <a href="/en-US/docs/Glossary/Mozilla_Firefox">Firefox</a>, <a href="/en-US/docs/Glossary/Google_Chrome">Chrome</a>, or <a href="/en-US/docs/Glossary/Microsoft_Edge">Edge</a>, are designed to present documents visually, for example, on a computer screen, projector, or printer.</p> <div class="notecard note"> <p><strong>Note:</strong> A browser is sometimes called a <a href="/en-US/docs/Glossary/User_agent">user agent</a>, which basically means a computer program that represents a person inside a computer system. Browsers are the main type of user agents we think of when talking about CSS, however, they are not the only ones. There are other user agents available, such as those that convert HTML and CSS documents into PDFs to be printed.</p> </div> <p>CSS can be used for very basic document text styling — for example, for changing the <a href="/en-US/docs/Web/CSS/color_value">color</a> and <a href="/en-US/docs/Web/CSS/font-size">size</a> of headings and links. It can be used to create a layout — for example, <a href="/en-US/docs/Web/CSS/Layout_cookbook/Column_layouts">turning a single column of text into a layout</a> with a main content area and a sidebar for related information. It can even be used for effects such as <a href="/en-US/docs/Web/CSS/CSS_animations">animation</a>. Have a look at the links in this paragraph for specific examples.</p></div></section><section aria-labelledby="css_syntax"><h2 id="css_syntax"><a href="#css_syntax">CSS syntax</a></h2><div class="section-content"><p>CSS is a rule-based language — you define the rules by specifying groups of styles that should be applied to particular elements or groups of elements on your web page.</p> <p>For example, you can decide to have the main heading on your page to be shown as large red text. The following code shows a very simple CSS rule that would achieve the styling described above:</p> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css notranslate"><code>h1 { color: red; font-size: 5em; } </code></pre></div> <ul> <li>In the above example, the CSS rule opens with a <a href="/en-US/docs/Glossary/CSS_Selector">selector</a>. This <em>selects</em> the HTML element that we are going to style. In this case, we are styling level one headings (<a href="/en-US/docs/Web/HTML/Element/Heading_Elements">h1</a>).</li> <li>We then have a set of curly braces <code>{ }</code>.</li> <li>Inside the braces will be one or more <strong>declarations</strong>, which take the form of <strong>property</strong> and <strong>value</strong> pairs. We specify the property (<code>color</code> in the above example) before the colon, and we specify the value of the property after the colon (<code>red</code> in this example).</li> <li>This example contains two declarations, one for <code>color</code> and the other for <code>font-size</code>. Each pair specifies a property of the element(s) we are selecting (<a href="/en-US/docs/Web/HTML/Element/Heading_Elements">h1</a> in this case), then a value that we'd like to give the property.</li> </ul> <p>CSS <a href="/en-US/docs/Glossary/Property/CSS">properties</a> have different allowable values, depending on which property is being specified. In our example, we have the <code>color</code> property, which can take various <a href="/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#color">color values</a>. We also have the <code>font-size</code> property. This property can take various <a href="/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#numbers_lengths_and_percentages">size units</a> as a value.</p> <p>A CSS stylesheet will contain many such rules, written one after the other.</p> <div class="code-example"><div class="example-header"><span class="language-name">css</span></div><pre class="brush: css notranslate"><code>h1 { color: red; font-size: 5em; } p { color: black; } </code></pre></div> <p>You will find that you quickly learn some values, whereas others you will need to look up. The individual property pages on MDN give you a quick way to look up properties and their values when you forget or when you want to know what else you can use as a value.</p> <div class="notecard note"> <p><strong>Note:</strong> You can find links to all the CSS property pages (along with other CSS features) listed on the MDN <a href="/en-US/docs/Web/CSS/Reference">CSS reference</a>. Alternatively, you should get used to searching for "mdn <em>css-feature-name</em>" in your favorite search engine whenever you need to find out more information about a CSS feature. For example, try searching for "mdn color" and "mdn font-size"!</p> </div></div></section><section aria-labelledby="css_modules"><h2 id="css_modules"><a href="#css_modules">CSS modules</a></h2><div class="section-content"><p>As there are so many things that you could style using CSS, the language is broken down into <em>modules</em>. You'll see reference to these modules as you explore MDN. Many of the documentation pages are organized around a particular module. For example, you could take a look at the MDN reference to the <a href="/en-US/docs/Web/CSS/CSS_backgrounds_and_borders">Backgrounds and Borders</a> module to find out what its purpose is and the properties and features it contains. In that module, you will also find a link to <em>Specifications</em> that defines the technology (also see the section below).</p> <p>At this stage, you don't need to worry too much about how CSS is structured; however, it can make it easier to find information if, for example, you are aware that a certain property is likely to be found among other similar things, and is therefore, probably in the same specification.</p> <p>For a specific example, let's go back to the Backgrounds and Borders module — you might think that it makes logical sense for the <a href="/en-US/docs/Web/CSS/background-color"><code>background-color</code></a> and <a href="/en-US/docs/Web/CSS/border-color"><code>border-color</code></a> properties to be defined in this module. And you'd be right.</p></div></section><section aria-labelledby="css_specifications"><h2 id="css_specifications"><a href="#css_specifications">CSS specifications</a></h2><div class="section-content"><p>All web standards technologies (HTML, CSS, JavaScript, etc.) are defined in giant documents called specifications (or "specs"), which are published by standards organizations (such as the <a href="/en-US/docs/Glossary/W3C">W3C</a>, <a href="/en-US/docs/Glossary/WHATWG">WHATWG</a>, <a href="/en-US/docs/Glossary/ECMA">ECMA</a>, or <a href="/en-US/docs/Glossary/Khronos">Khronos</a>) and define precisely how those technologies are supposed to behave.</p> <p>CSS is no different — it is developed by a group within the W3C called the <a href="https://www.w3.org/Style/CSS/" class="external" target="_blank">CSS Working Group</a>. This group is made of representatives of browser vendors and other companies who have an interest in CSS. There are also other people, known as <em>invited experts</em>, who act as independent voices; they are not linked to a member organization.</p> <p>New CSS features are developed or specified by the CSS Working Group — sometimes because a particular browser is interested in having some capability, other times because web designers and developers are asking for a feature, and sometimes because the Working Group itself has identified a requirement. CSS is constantly developing, with new features becoming available. However, a key thing about CSS is that everyone works very hard to never change things in a way that would break old websites. A website built in 2000, using the limited CSS available then, should still be usable in a browser today!</p> <p>As a newcomer to CSS, it is likely that you will find the CSS specs overwhelming — they are intended for engineers to use to implement support for the features in user agents, not for web developers to read to understand CSS. Many experienced developers would much rather refer to MDN documentation or other tutorials. Nevertheless, it is worth knowing that these specs exist and understanding the relationship between the CSS you are using, the browser support (see below), and the specs.</p></div></section><section aria-labelledby="browser_support_information"><h2 id="browser_support_information"><a href="#browser_support_information">Browser support information</a></h2><div class="section-content"><p>After a CSS feature has been specified, then it is only useful for us in developing web pages if one or more browsers have implemented the feature. This means that the code has been written to turn the instruction in our CSS file into something that can be output to the screen. We'll look at this process more in the lesson <a href="/en-US/docs/Learn/CSS/First_steps/How_CSS_works">How CSS works</a>. It is unusual for all browsers to implement a feature at the same time, and so there is usually a gap where you can use some part of CSS in some browsers and not in others. For this reason, being able to check implementation status is useful.</p> <p>The browser support status is shown on every MDN CSS property page in a table named "Browser compatibility". Consult the information in that table to check if the property can be used on your website. For an example, see the <a href="/en-US/docs/Web/CSS/font-family#browser_compatibility">browser compatibility table for the CSS <code>font-family</code> property</a>.</p> <p>Based on your requirements, you can use the browser compatibility table to check how this property is supported across various browsers, or check if your specific browser and the version you have support the property, or if there are any caveats you should be aware of for the browser and version you are using.</p></div></section><section aria-labelledby="summary"><h2 id="summary"><a href="#summary">Summary</a></h2><div class="section-content"><p>You made it to the end of the article! 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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/First_steps/What_is_CSS","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"What is CSS?","mdn_url":"/en-US/docs/Learn/CSS/First_steps/What_is_CSS","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 open=\"\"><summary>CSS first steps</summary><ol><li><a href=\"/en-US/docs/Learn/CSS/First_steps\">CSS first steps</a></li><li><em><a href=\"/en-US/docs/Learn/CSS/First_steps/What_is_CSS\" aria-current=\"page\">What is CSS?</a></em></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><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><a href=\"/en-US/docs/Learn/CSS/Building_blocks/Overflowing_content\">Overflowing content</a></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 \n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/First_steps\"><span class=\"button-wrap\"> Overview: CSS first steps</span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/First_steps/Getting_started\"><span class=\"button-wrap\"> Next </span></a></li>\n</ul>\n<p><strong><a href=\"/en-US/docs/Glossary/CSS\">CSS</a></strong> (Cascading Style Sheets) allows you to create great-looking web pages, but how does it work under the hood? This article explains what CSS is with a simple syntax example and also covers some key terms about the language.</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>, and HTML basics (study\n <a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML\">Introduction to HTML</a>.)\n </td>\n </tr>\n <tr>\n <th scope=\"row\">Objective:</th>\n <td>To learn what CSS is.</td>\n </tr>\n </tbody>\n</table></figure>\n<p>In the <a href=\"/en-US/docs/Learn/HTML/Introduction_to_HTML\">Introduction to HTML</a> module, we covered what HTML is and how it is used to mark up documents. These documents will be readable in a web browser. Headings will look larger than regular text, paragraphs break onto a new line and have space between them. Links are colored and underlined to distinguish them from the rest of the text. What you are seeing are the browser's default styles — very basic styles — that the browser applies to HTML to make sure that the page will be basically readable even if no explicit styling is specified by the author of the page.</p>\n<p>\n <img src=\"/en-US/docs/Learn/CSS/First_steps/What_is_CSS/html-example.png\" alt=\"The default styles used by a browser\" width=\"1385\" height=\"594\" loading=\"lazy\">\n</p>\n<p>However, the web would be a boring place if all websites looked like that. Using CSS, you can control exactly how HTML elements look in the browser, presenting your markup using whatever design you like.</p>\n<p>For more on browser/default styles, check out the following video:</p><iframe width=\"560\" height=\"315\" src=\"https://www.youtube-nocookie.com/embed/spK_S0HfzFw\" title=\"YouTube video\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen=\"\" loading=\"lazy\"></iframe>"}},{"type":"prose","value":{"id":"what_is_css_for","title":"What is CSS for?","isH3":false,"content":"<p>As we have mentioned before, CSS is a language for specifying how documents are presented to users — how they are styled, laid out, etc.</p>\n<p>A <strong>document</strong> is usually a text file structured using a markup language — <a href=\"/en-US/docs/Glossary/HTML\">HTML</a> is the most common markup language, but you may also come across other markup languages such as <a href=\"/en-US/docs/Glossary/SVG\">SVG</a> or <a href=\"/en-US/docs/Glossary/XML\">XML</a>.</p>\n<p><strong>Presenting</strong> a document to a user means converting it into a form usable by your audience. <a href=\"/en-US/docs/Glossary/Browser\">Browsers</a>, like <a href=\"/en-US/docs/Glossary/Mozilla_Firefox\">Firefox</a>, <a href=\"/en-US/docs/Glossary/Google_Chrome\">Chrome</a>, or <a href=\"/en-US/docs/Glossary/Microsoft_Edge\">Edge</a>, are designed to present documents visually, for example, on a computer screen, projector, or printer.</p>\n<div class=\"notecard note\">\n <p><strong>Note:</strong> A browser is sometimes called a <a href=\"/en-US/docs/Glossary/User_agent\">user agent</a>, which basically means a computer program that represents a person inside a computer system. Browsers are the main type of user agents we think of when talking about CSS, however, they are not the only ones. There are other user agents available, such as those that convert HTML and CSS documents into PDFs to be printed.</p>\n</div>\n<p>CSS can be used for very basic document text styling — for example, for changing the <a href=\"/en-US/docs/Web/CSS/color_value\">color</a> and <a href=\"/en-US/docs/Web/CSS/font-size\">size</a> of headings and links. It can be used to create a layout — for example, <a href=\"/en-US/docs/Web/CSS/Layout_cookbook/Column_layouts\">turning a single column of text into a layout</a> with a main content area and a sidebar for related information. It can even be used for effects such as <a href=\"/en-US/docs/Web/CSS/CSS_animations\">animation</a>. Have a look at the links in this paragraph for specific examples.</p>"}},{"type":"prose","value":{"id":"css_syntax","title":"CSS syntax","isH3":false,"content":"<p>CSS is a rule-based language — you define the rules by specifying groups of styles that should be applied to particular elements or groups of elements on your web page.</p>\n<p>For example, you can decide to have the main heading on your page to be shown as large red text. The following code shows a very simple CSS rule that would achieve the styling described above:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css notranslate\"><code>h1 {\n color: red;\n font-size: 5em;\n}\n</code></pre></div>\n<ul>\n <li>In the above example, the CSS rule opens with a <a href=\"/en-US/docs/Glossary/CSS_Selector\">selector</a>. This <em>selects</em> the HTML element that we are going to style. In this case, we are styling level one headings (<a href=\"/en-US/docs/Web/HTML/Element/Heading_Elements\">h1</a>).</li>\n <li>We then have a set of curly braces <code>{ }</code>.</li>\n <li>Inside the braces will be one or more <strong>declarations</strong>, which take the form of <strong>property</strong> and <strong>value</strong> pairs. We specify the property (<code>color</code> in the above example) before the colon, and we specify the value of the property after the colon (<code>red</code> in this example).</li>\n <li>This example contains two declarations, one for <code>color</code> and the other for <code>font-size</code>. Each pair specifies a property of the element(s) we are selecting (<a href=\"/en-US/docs/Web/HTML/Element/Heading_Elements\">h1</a> in this case), then a value that we'd like to give the property.</li>\n</ul>\n<p>CSS <a href=\"/en-US/docs/Glossary/Property/CSS\">properties</a> have different allowable values, depending on which property is being specified. In our example, we have the <code>color</code> property, which can take various <a href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#color\">color values</a>. We also have the <code>font-size</code> property. This property can take various <a href=\"/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#numbers_lengths_and_percentages\">size units</a> as a value.</p>\n<p>A CSS stylesheet will contain many such rules, written one after the other.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">css</span></div><pre class=\"brush: css notranslate\"><code>h1 {\n color: red;\n font-size: 5em;\n}\n\np {\n color: black;\n}\n</code></pre></div>\n<p>You will find that you quickly learn some values, whereas others you will need to look up. The individual property pages on MDN give you a quick way to look up properties and their values when you forget or when you want to know what else you can use as a value.</p>\n<div class=\"notecard note\">\n <p><strong>Note:</strong> You can find links to all the CSS property pages (along with other CSS features) listed on the MDN <a href=\"/en-US/docs/Web/CSS/Reference\">CSS reference</a>. Alternatively, you should get used to searching for \"mdn <em>css-feature-name</em>\" in your favorite search engine whenever you need to find out more information about a CSS feature. For example, try searching for \"mdn color\" and \"mdn font-size\"!</p>\n</div>"}},{"type":"prose","value":{"id":"css_modules","title":"CSS modules","isH3":false,"content":"<p>As there are so many things that you could style using CSS, the language is broken down into <em>modules</em>. You'll see reference to these modules as you explore MDN. Many of the documentation pages are organized around a particular module. For example, you could take a look at the MDN reference to the <a href=\"/en-US/docs/Web/CSS/CSS_backgrounds_and_borders\">Backgrounds and Borders</a> module to find out what its purpose is and the properties and features it contains. In that module, you will also find a link to <em>Specifications</em> that defines the technology (also see the section below).</p>\n<p>At this stage, you don't need to worry too much about how CSS is structured; however, it can make it easier to find information if, for example, you are aware that a certain property is likely to be found among other similar things, and is therefore, probably in the same specification.</p>\n<p>For a specific example, let's go back to the Backgrounds and Borders module — you might think that it makes logical sense for the <a href=\"/en-US/docs/Web/CSS/background-color\"><code>background-color</code></a> and <a href=\"/en-US/docs/Web/CSS/border-color\"><code>border-color</code></a> properties to be defined in this module. And you'd be right.</p>"}},{"type":"prose","value":{"id":"css_specifications","title":"CSS specifications","isH3":false,"content":"<p>All web standards technologies (HTML, CSS, JavaScript, etc.) are defined in giant documents called specifications (or \"specs\"), which are published by standards organizations (such as the <a href=\"/en-US/docs/Glossary/W3C\">W3C</a>, <a href=\"/en-US/docs/Glossary/WHATWG\">WHATWG</a>, <a href=\"/en-US/docs/Glossary/ECMA\">ECMA</a>, or <a href=\"/en-US/docs/Glossary/Khronos\">Khronos</a>) and define precisely how those technologies are supposed to behave.</p>\n<p>CSS is no different — it is developed by a group within the W3C called the <a href=\"https://www.w3.org/Style/CSS/\" class=\"external\" target=\"_blank\">CSS Working Group</a>. This group is made of representatives of browser vendors and other companies who have an interest in CSS. There are also other people, known as <em>invited experts</em>, who act as independent voices; they are not linked to a member organization.</p>\n<p>New CSS features are developed or specified by the CSS Working Group — sometimes because a particular browser is interested in having some capability, other times because web designers and developers are asking for a feature, and sometimes because the Working Group itself has identified a requirement. CSS is constantly developing, with new features becoming available. However, a key thing about CSS is that everyone works very hard to never change things in a way that would break old websites. A website built in 2000, using the limited CSS available then, should still be usable in a browser today!</p>\n<p>As a newcomer to CSS, it is likely that you will find the CSS specs overwhelming — they are intended for engineers to use to implement support for the features in user agents, not for web developers to read to understand CSS. Many experienced developers would much rather refer to MDN documentation or other tutorials. Nevertheless, it is worth knowing that these specs exist and understanding the relationship between the CSS you are using, the browser support (see below), and the specs.</p>"}},{"type":"prose","value":{"id":"browser_support_information","title":"Browser support information","isH3":false,"content":"<p>After a CSS feature has been specified, then it is only useful for us in developing web pages if one or more browsers have implemented the feature. This means that the code has been written to turn the instruction in our CSS file into something that can be output to the screen. We'll look at this process more in the lesson <a href=\"/en-US/docs/Learn/CSS/First_steps/How_CSS_works\">How CSS works</a>. It is unusual for all browsers to implement a feature at the same time, and so there is usually a gap where you can use some part of CSS in some browsers and not in others. For this reason, being able to check implementation status is useful.</p>\n<p>The browser support status is shown on every MDN CSS property page in a table named \"Browser compatibility\". Consult the information in that table to check if the property can be used on your website. For an example, see the <a href=\"/en-US/docs/Web/CSS/font-family#browser_compatibility\">browser compatibility table for the CSS <code>font-family</code> property</a>.</p>\n<p>Based on your requirements, you can use the browser compatibility table to check how this property is supported across various browsers, or check if your specific browser and the version you have support the property, or if there are any caveats you should be aware of for the browser and version you are using.</p>"}},{"type":"prose","value":{"id":"summary","title":"Summary","isH3":false,"content":"<p>You made it to the end of the article! Now that you have some understanding of what CSS is, let's move on to <a href=\"/en-US/docs/Learn/CSS/First_steps/Getting_started\">Getting started with CSS</a>, where you can start to write some CSS yourself.</p><ul class=\"prev-next\">\n \n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/First_steps\"><span class=\"button-wrap\"> Overview: CSS first steps</span></a></li>\n <li><a class=\"button secondary\" href=\"/en-US/docs/Learn/CSS/First_steps/Getting_started\"><span class=\"button-wrap\"> Next </span></a></li>\n</ul>"}}],"toc":[{"text":"What is CSS for?","id":"what_is_css_for"},{"text":"CSS syntax","id":"css_syntax"},{"text":"CSS modules","id":"css_modules"},{"text":"CSS specifications","id":"css_specifications"},{"text":"Browser support information","id":"browser_support_information"},{"text":"Summary","id":"summary"}],"summary":"You made it to the end of the article! Now that you have some understanding of what CSS is, let's move on to Getting started with CSS, where you can start to write some CSS yourself.","popularity":0.0157,"modified":"2024-07-25T20:16:09.000Z","other_translations":[{"locale":"de","title":"Was ist CSS?","native":"Deutsch"},{"locale":"es","title":"¿Qué es el CSS?","native":"Español"},{"locale":"fr","title":"Qu'est-ce que CSS ?","native":"Français"},{"locale":"ja","title":"CSS とは何か","native":"日本語"},{"locale":"ko","title":"CSS 란 무엇인가?","native":"한국어"},{"locale":"pt-BR","title":"O que é CSS?","native":"Português (do Brasil)"},{"locale":"ru","title":"Что такое CSS?","native":"Русский"},{"locale":"zh-CN","title":"什么是 CSS?","native":"中文 (简体)"},{"locale":"zh-TW","title":"CSS 是什麼？","native":"正體中文 (繁體)"}],"pageType":"learn-module-chapter","source":{"folder":"en-us/learn/css/first_steps/what_is_css","github_url":"https://github.com/mdn/content/blob/main/files/en-us/learn/css/first_steps/what_is_css/index.md","last_commit_url":"https://github.com/mdn/content/commit/44b18841ff739fbf1a5450805d85f839fa3e68a5","filename":"index.md"},"short_title":"What is CSS?","parents":[{"uri":"/en-US/docs/Learn","title":"Guides"},{"uri":"/en-US/docs/Learn/CSS","title":"CSS"},{"uri":"/en-US/docs/Learn/CSS/First_steps","title":"CSS first steps"},{"uri":"/en-US/docs/Learn/CSS/First_steps/What_is_CSS","title":"What is CSS?"}],"pageTitle":"What is CSS? - Learn web development | MDN","noIndexing":false}}</script></body></html>