A Mozilla bug

CSS rgba(...) colours are fun. Firefox 3 doesn't handle them quite perfectly when applied to the <html> tag, though. I haven't seen this sort of reflow bug (leaving shadows behind dragged objects) much since I, pretty much, ceased using Windows machines a few years ago.

Nostalgia to be had! Try this bookmarklet, say, on this page and play around with the mock window at your heart's content.