My web site contains many files with names which contain "problematic" characters, e.g. "space" as in the above example URL.

When checking HTML syntax with "http://validator.w3.org/check/referer" my web server (Apache) gets a correctly escaped path:
"GET /Vintage/Sinclair/80/Timex%20Peripherials/ HTTP/1.1"

For "http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Fk1.dyndns.org%2FVintage%2FSinclair%2F80%2FTimex%2520Peripherials%2F"
my web server gets a correctly escaped path:
"GET /Vintage/Sinclair/80/Timex%20Peripherials/ HTTP/1.1"
and the CSS Validator says "OK" for the page.

But for "http://jigsaw.w3.org/css-validator/check/referer" from this page my web server gets an unescaped path:
"GET /Vintage/Sinclair/80/Timex Peripherials/ HTTP/1.1"
and consequently returns a "Bad Request" error to the CSS Validator.

The result page for the successful CSS validation states to use:
"http://jigsaw.w3.org/css-validator/validator?uri=http://k1.dyndns.org/Vintage/Sinclair/80/Timex%20Peripherials/"
or 
"http://jigsaw.w3.org/css-validator/check/referer"
to include in the page itself for later easy CSS validation, as i have done on this page.

Greetings,

    ... kio !