Bad "!important" check: "!potato" works fine.

[Drugoy]

Currently, seems like USM uses it's own rules, which don't fit the CSS standard.

toolbarbutton { background-color: red ! }

toolbarbutton { background-color: grey !potato; }

These styles work, although they shouldn't.

Obviously, there is a bad check in the code: it checks whether anything after "!" contains any letters other than "i", "m", "p", "o", "r", "t", "a" and "n".

So "!ports" won't work, because it fails this check due to present illegal letter "s", but "!port", "!ramp" and "!it" won't fail this check and the style will get applied.

[grssam]

This will also be solved, once the property validation is done.