Hi all,
I just filed a bug that likely affects all Moodle Themes :
https://tracker.moodle.org/browse/MDL-38441
It's a bit of a weird one, and only shows up in older verisions of IE before 10, and possibly then only when you're out of theme developer mode, so you might well be unaware that it's affecting your theme. As outlined with numbers in the bug, I'm guessing this affects basically every Moodle theme.
Note some further investigation shows this is much less likely to affect you. There are partial mitigations already in place for this, so only if a) your installed plugins, b) your parent theme or c) your current theme individually cross the 4095 selector limit are you likely to see any problem, which is fairly unlikely unless you're doing something unusual.