CSS File Extension

Have a problem opening a .CSS file? We collect information about file formats and can explain what CSS files are. Additionally we recommend software suitable for opening or converting such files.

What is the .CSS file type?

Derived from the standard abbreviation for Cascading Style Sheets (CSS), the .css filename extension represents the CSS Stylesheet File (.css) file type. One of the core web technologies devised and promoted by the World Wide Web Consortium (W3C), CSS governs the presentational side of HTML/XHTML/XML documents and allows web authors to completely separate structure from presentation. CSS stylesheets are used on all sensibly designed web sites, and beyond that, to control appearance settings in web browsers and other desktop/mobile applications.

The .css file is a CSS stylesheet. It is a regular text file that lists CSS formatting rules grouped by selectors (HTML tags, etc.) to which the rules apply in a cascading fashion. CSS stylesheets can be embedded in web documents or linked as external .css files through the <link> tag. Usually, a single web page references several stylesheets for different presentation options (mobile screen, printing). Any CSS stylesheet file can be viewed and edited with a simplest text editor, however, power text editors or dedicated CSS authoring tools with syntax highlighting and built-in reference are preferred by most.


Software to open or convert CSS files

You can open CSS files with the following programs: 

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