Description

We use the @charset at-rule to specify the character encoding of an external style sheet. The at-rule must be followed by a quoted string value and a semicolon; the string must contain a valid encoding name from the IANA registry.

For obvious reasons, if it’s present, an @charset rule must be the very first thing in the CSS file. The only item that can precede it is a Unicode byte order mark (BOM).

You’ll rarely need to use an @charset rule in your style sheets. A user agent can deduce the character encoding of a CSS style sheet in four different ways, and if all of those fail, it uses a default.

For an external style sheet, a user agent will look for the following items:

• a charset attribute in a Content-Type HTTP header (or similar) sent by the web server
• a Unicode byte order mark, or an @charset at-rule
• a charset attribute specified in the <link> tag from which the HTML document links to the style sheet
• the encoding of the referring document or style sheet

This list defines the items in order of descending priority, and the first one that’s found will determine the style sheet’s encoding. If none are found, the user agent will assume the character encoding is UTF-8.

Compatibility

In Internet Explorer versions up to and including 7, an @charset rule will not fail if the encoding is specified without quotes, even though it should.

In Firefox 1.0, an @charset rule will work only if it’s specified without quotes, on which it should actually fail.