Ted, try generating the gallery with one of the default (built-in) themes. If it displays well in Firefox, then the issue is that some theme editing you have performed introduces the display anomaly in Firefox. It would be useful if you could tell us which particular edit is the culprit so we can prevent the Theme Editor from performing such edits.
It is always a good idea to test any edits in Internet Explorer and Firefox. Even though IE is still the prevalent browser, many people prefer Firefox. We test all our themes for various platform/browser configurations. However, it is possible that the flexibility provided by the Theme Editor does introduce some quirks, which we will fix as soon as these are identified specifically.
Our site analytics logs show that visitors to our Web site have:
- 73% - Internet Explorer
- 22% - Firefox
- 2.3% - Safari (default Web browser for Apple's Mac computers)
- 1.6% - Opera