Admin Forum:How to change table header background colour?

I'm trying to convert an old web page of mine, listing all the 140-odd named colours recognised by web browsers, to MediaWiki marekup so I can post it here as a blog page. I'm sure this would be of benefit to wiki creators. The experimental beginnings of this page can be found at User:RobertATfm/Sandbox.

The problem is, although the "color=white" attribute of the table style works in the table header row, the "background=#404040" doesn't, so the header ends up as unreadable white on white. It would be acceptable if neither attribute worked, so that the header row would be readable; but to have one work and not the other is unacceptable. And of course the table needs a header row, for without one it wouldn't be sortable.

How do I resolve this problem? — RobertATfm (talk) 20:26, November 12, 2012 (UTC)