Per-user ekw theme preferences.
Now with canned schemes:
The stylesheets that these themes use are pretty straightfoward, and should work on any modern (2004 or later) web browser.
You're not using ekw theme, so this page won't do anything for you.
Colors can be any valid HTML color: Either hex triplets (#RRGGBB) or named colors (e.g. papayawhip). See for some information that's actually useful. E2 Color Toy will help translate normal numbers into HTML colors, and it will also generate gradients from one color to another.
Font information is expressed in CSS terms: 12 pixels is expressed as "12px", 12 points is expressed as "12pt". You can also do percentages. Percentages of what? Damned if I know! Font names are comma-separated lists, such as "Helvetica, Arial, sans-serif", where the browser tries to find the first one, then moves on down the list until it finds one that's installed on your computer.