That's because Paul told you....
This code will work in Opera, look odd in IE and do nothing in Firefox.
I suspect you're looking in IE?
Form controls are troublesome to style and impossible to get consistency cross browser so they're usually best left alone not only for this reason but also because users are familiar with how form controls look and changing them is likely to confuse users rather than improve usability.
Apart from maybe using an image for a submit button and altering the default font, I'd generally leave form controls as their default style.