I am studying the css methods Google uses to create their ui. I realized that the css code on their home page contains no reference to their search box; it seems like just a naked input tag, with not a border, background image or any of the conventions normally used to stylize a border. And yet it can display not only a hue and a kind of gradient, but it is slightly round and also reacts to the cursor focus.
So, your guess is as good as mine. Please use your Firebug to check it out and help me get to the bottom of this riddle.
EDIT: Just to be clear, I'm not trying to make an aesthetic judgment. Although I think minimalism of Google's homepage is fantastic, I am really interested to find out the techniques they used to stylize the borders around their search box -- without using any css whatsoever.