I know that it’s finding / using the stylesheet though, because I have
another entry in there that does get used.
If it’s purely a CSS-issue, there are two tried-and-true things to check
What doctype are you specifying in your HTML document? To
trouble-shoot display issues with CSS, it’s really helpful to make
sure you’re triggering “Standards” mode in both MSIE, Gecko-, and
kHTML/Webkit-based browsers (as opposed to Quirks mode).
Assuming you are using a valid doctype and it’s triggering
Standards-mode, does your CSS code validate? And while you’re at it,
it’s good idea to check and validate your markup, too.
About half the time, fixing either of these two issues fixes the display
issue. If that doesn’t fix the issue, you might want to either post
your CSS code here or on the CSS-List.