add explicit "px" measurements to header padding

On my system - OSX 10.8, Opera 20/Safari 6.0.1, jQuery 2.1.0 (possibly others, too, but I don't have them available to check) - the specified padding for each header cell div wasn't actually being added at all. My jquery-fu is not strong enough to adequately explain why (I just got started, like, yesterday ;) ), but my best guess is that .css() has some sort of validation check it's doing such that "padding":"1 3 2 5" doesn't pass. Explicitly designating those values as pixel measurements, though, gets it through.
Hope this helps!