Why specify @charset “UTF-8”; in your CSS file?

This is useful in contexts where the encoding is not told per HTTP header or other meta data, e.g. the local file system.

Imagine the following stylesheet:

[rel="external"]::after
{
    content: ' ↗';
}

If a reader saves the file to a hard drive and you omit the @charset rule, most browsers will read it in the OS’ locale encoding, e.g. Windows-1252, and insert ↗ instead of an arrow.

Unfortunately, you cannot rely on this mechanism as the support is rather … rare.
And remember that on the net an HTTP header will always override the @charset rule.

The correct rules to determine the character set of a stylesheet are in order of priority:

  1. HTTP Charset header.
  2. Byte Order Mark.
  3. The first @charset rule.
  4. UTF-8.

The last rule is the weakest, it will fail in some browsers.
The charset attribute in <link rel="stylesheet" charset="utf-8"> is obsolete in HTML 5.
Watch out for conflict between the different declarations. They are not easy to debug.

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