CSS

===Sources===
CSS, or Cascading Style Sheets, offers a flexible way to style web content, with styles originating from browser defaults, user preferences, or web designers. These styles can be applied inline, within an HTML document, or through external .css files for broader consistency. Not only does this simplify web development by promoting reusability and maintainability, it also improves site performance because styles can be offloaded into dedicated .css files that browsers can cache. Additionally, even if the styles cannot be loaded or are disabled, this separation maintains the accessibility and readability of the content, ensuring that the site is usable for all users, including those with disabilities. Its multi-faceted approach, including considerations for selector specificity, rule order, and media types, ensures that websites are visually coherent and adaptive across different devices and user needs, striking a balance between design intent and user accessibility.

====Multiple style sheets====

Multiple style sheets can be imported. Different styles can be applied depending on the output device being used; for example, the screen version can be quite different from the printed version, so authors can tailor the presentation appropriately for each medium.

====Cascading====
The style sheet with the highest priority controls the content display. Declarations not set in the highest priority source are passed on to a source of lower priority, such as the user agent style. The process is called ''cascading''.

One of the goals of CSS is to allow users greater [[Style sheet (web development)#Customization|control over presentation]]. Someone who finds red italic headings difficult to read may apply a different style sheet. Depending on the browser and the website, a user may choose from various style sheets provided by the designers, or may remove all added styles, and view the site using the browser's default styling, or may override just the red italic heading style without altering other attributes. Browser extensions like [[Stylish]] and [[Stylus (browser extension)|Stylus]] have been created to facilitate the management of such user style sheets. In the case of large projects, cascading can be used to determine which style has a higher priority when developers do integrate third-party styles that have conflicting priorities, and to further resolve those conflicts. Additionally, cascading can help create themed designs, which help designers fine-tune aspects of a design without compromising the overall layout.  

=====CSS priority scheme=====
{| class="wikitable"
|+ CSS priority scheme (highest to lowest)
|-
! Priority !! CSS source type !! Description
|-
| 1 || Importance || The "{{code|lang=css|code=!important}}" annotation overwrites the previous priority types
|-
| 2 || Inline || A style applied to an HTML element via HTML "style" attribute
|-
| 3 || Media Type || A property definition applies to all media types unless a media-specific CSS is defined
|-
| 4 || User defined || Most browsers have the accessibility feature: a user-defined CSS
|-
| 5 || Selector specificity || A specific contextual selector ({{code|lang=css|code=#heading p}}) overwrites generic definition
|-
| 6 || Rule order || Last rule declaration has a higher priority
|-
| 7 || Parent inheritance || If a property is not specified, it is inherited from a parent element
|-
| 8 || CSS property definition in HTML document || CSS rule or CSS inline style overwrites a default browser value
|-
| 9 || Browser default || The lowest priority: browser default value is determined by W3C initial value specifications
|}