My desktop environment (including browser) is configured to have white text and dark background. With many websites that don't set the text color for input boxes, or set both text color and background color, is it OK. But StackOverflow is unfortunately not one of them...
Asking, answering questions and writing comments is OK (input box background is not set), but search box has white background, so I see silver text on white background, which is not very readable.
color: Black; please be added to CSS stylesheet for
PS. captcha input box has similar (yet opposite) problem - text color is set to black, but background color is not set :)