There may be an addon that would help in Firefox but it looks like some of the html isn't valid. I.E. tends to ignore stuff like that but Firefox observes the standards to a far greater degree.
Here's what the W3C test page reveals:
http://tinyurl.com/yvacm2The link is for the validation of capitolhillblue.com, not readerrant.capitolhillblue.com, so it isn't exactly relevant in this specific instance. I haven't checked the W3C validation for it, because it is a bit more problematical, since it redirects to ubbthreads.php.
I believe the solution can be properly addressed by adjusting the CSS code, and is only a problem when quotes are nested. I haven't picked through the CSS, but I suspect somewhere within the quote style code is/are element(s) that Firefox renders as a forced minimum width. Let me see if I can explain.
Here's a ASCII depiction of a quote layout:
---------------___________________________
--left-margin--|.........................|--right margin--
---------------|...quote content.........|----------------
---------------|.........................|----------------
---------------|_________________________|----------------
If Firefox renders the box with the quote content as a forced minimum width, when a quote is nested, both margins, and a forced minimum width quote box get placed inside, which breaks the initial quote's width styling, forcing the horizontal scroll bar as an adjustment.
This is just a quick initial guess, but if I were sure that someone at CHB was interested in fixing the bug, I'd be willing to invest time towards that goal, and I do have a bit of experience tweaking CSS, HTML and XHTML, although my PHP experience is weak. If it's just the CSS, it shouldn't be a big problem; it's probably nothing more than assuring that a quote within a quote has a different set of style rules.
Also, I just ran ubbthreads_1.css through my CSS editor, and it shows multiple errors across different browsers, and different browser versions. The two main ones are:
- Line 4 : Font-name with spaces needs to be enclosed by quotes
- Line 381 : length units must be specified. Here width is listed as just 500. My guess is 500px was intended.
Neither one of these look to be where the problem is though. Still, it's always a good idea to assure that no errors are thrown in code, whether it causes runtime problems or not, and both of those are very simple fixes.