Well, the id is cleaned up in inc/pageutils.php - function sectionID() which calls cleanID() which takes care of all special chars beside . (dot)
A str_replace() in sectionID() should fix the problem. There is no reserved keywords in the CCS identifier syntax, but different browsers may have parsers designed otherwise (using CSS on auto as a headline works in Firefox 3.0)
# In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+00A1 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code (see next item). For instance, the identifier "B&W?" may be written as "B\&W\?" or "B\26 W\3F".
Note that Unicode is code-by-code equivalent to ISO 10646 (see [UNICODE] and [ISO10646]).