It appears that the CSS validator is unable to find the stylesheet within an
XHTML1.0 document, if the document is UTF-8 or UTF-16 encoded. The URL provided
validates as XHTML by the markup validator but the CSS validator seems unable to
locate the embedded STYLE tag.

To test the case further, I tried to verify an ANSI-encoded version of the exact
same file (available via the url below) . Naturally, markup validator could not
even parse it ("...it contained one or more bytes that I cannot interpret as
utf-16...") but the CSS validator was able to find the STYLE section and
validate it.

http://exiclick.com/snk/index.htm (The original)
http://exiclick.com/snk/index2.htm (Incorrectly ANSI-encoded test file)