http vs. bom
An HTTP encoding declaration for a stylesheet takes precedence over a UTF-8 signature.
This test is only valid if the user agent recognises the HTTP and BOM declarations.
The HTML page is served as ISO 8859-1 and has a class name ýäè. This only matches the sequence of bytes in the selector of the CSS file if the selector is read as ISO 8859-1. The style sheet has a UTF-8 signature at the start, but the HTTP header for the style sheet says ISO 8859-1. If the HTTP header overrides the @charset rule, the selector will match the class name and the test will pass.
Text as read from the style sheet: (if blank, the style sheet hasn't been read at all)