I don't know if this is already planned or discussed, but I think it would be nice to be able to change in the user control several style options. Namely, the three I like changing most often are background color, foreground color, and line height, so it would be cool if there could be a customized way to set those.

I know that Firefox has the Stylish extension (among others), but it would be cool to have some standard theme settings that would be account specific and carry across browsers and computers.

Of course, this can be taken further into customizable themes or a standard list of themes in the style of http://www.csszengarden.com/ for viewing and exporting.

I see this as a luxury rather than a necessity, but I want to throw the idea out here so that in the future it could be an option.