Editing Style sheet (web development) (section)

{{Short description|Form of separation of content and presentation for web design}}
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A web '''style sheet''' is a form of [[separation of content and presentation]] for [[web design]] in which the [[Markup (computer programming)|markup]] (i.e., [[HTML]] or [[XHTML]]) of a [[webpage]] contains the page's semantic content and structure, but does not define its visual layout (style). Instead, the style is defined in an external style sheet file using a [[style sheet language]] such as [[Cascading Style Sheets|CSS]] or [[XSLT]]. This design approach is identified as a "separation" because it largely supersedes the antecedent methodology in which a page's markup defined both style and structure.

The philosophy underlying this methodology is a specific case of [[separation of concerns]].