At One Place

.css files

.css file
Cascading Style Sheet
The text file that tells a web page how to look.

What opens a .css file

Windows
Visual Studio Code, Notepad (built in), Any web browser (shows source)
macOS
Visual Studio Code, TextEdit (built in), Any web browser (shows source)
Linux
Visual Studio Code, Text Editor (built in)
In a browser
CodePen, CodeSandbox

What a .css file is

CSS holds the rules — colours, fonts, spacing, layout — applied to HTML elements, and is a W3C standard. It is plain text you can read and edit in anything, and it does nothing on its own: opening a .css file in a browser shows the source, not a page. Sites often ship a minified version with all whitespace stripped, which is valid but painful to read.

Converting it

A .css file is commonly converted to .scss, .less or .txt. It is a plain text format, so any text editor can open and edit it directly.

Details

Extension
.css
Full name
Cascading Style Sheet
Category
Code and scripts
MIME type
text/css
Created by
W3C
Format
Plain text

Common questions

How do I open a .css file?
On Windows use Visual Studio Code; on macOS use Visual Studio Code; on Linux use Visual Studio Code. The text file that tells a web page how to look.
What is a .css file?
Cascading Style Sheet. CSS holds the rules — colours, fonts, spacing, layout — applied to HTML elements, and is a W3C standard. It is plain text you can read and edit in anything, and it does nothing on its own: opening a .css file in a browser shows the source, not a page.
Can I convert a .css file?
Yes. It is usually converted to .scss, .less or .txt, either by exporting from one of the programs listed above or with a format converter.

Related pages

Sources

  1. Media Types Registry — IANA
  2. Official vendor product documentation — At One Place

How these figures are compiled and checked