I've noticed a problem in which the font size dropdown in the Home tab in the ribbon doesn't work in the dropdown controls that are used for SharePoint lists (i.e., the Lookup control). I've also tried this scenario in both browsers, and I'm seeing the issue in which the fonts in Internet Explorer are a lot bigger than they should be. I'll contact the owners of those controls to get them fixed.
@scotthanks you mentioned that some of it works in IE, while others work in Chrome; I've found out that in Chrome it seems to work fairly well (see details below). Can you post some screen capture of what doesn't work in Chrome for you?
To test that I've built an app that uses both dropdowns from sharepoint lists (Lookup controls, inside forms), and from "regular" dropdown controls. I've set the font of one of them to a small value, and the other to a large value:
And here's what I see when I expand all dropdowns in Chrome - it looks correct to me (again, please post a screenshot if you see differently):
In IE, however, I see the font size in the dropdown being a lot larger. This is a bug, and as I mentioned I'll report it to the owner of that control:
