This is not the problem. The parts of a HTML form control that are not defined through CSS are taken from the system default theme by the browser. Usually this

This is not the problem. The parts of a HTML form control that are not defined through CSS are taken from the system default theme by the browser. Usually this is white on black, but this is NOT guaranteed (e.g. high contrast schemes for vision impaired users). Web designers tend to use these default schemes when writing the CSS for a web site. So they write only the attributes they need to make it work on their setup. So if the textbox background or text color is already what they want, they don't define it. This the browser takes the non-matching system color instead- precisely because it was set in a "dumbass" scheme (I resent this term).