I use Aptana Studio 3 for my web development, and I love it except for a few small gripes. One of these gripes is that Aptana decides to treat some CSS parameters as invali
You can add filters for CSS errors, or turn off CSS validation altogether. Please see here for more information:
http://wiki.appcelerator.org/display/tis/Adding+custom+error+message+filters+to+the+Problems+View