I have a 16x16 PNG that I want to use for my favicon. It works fine in modern browsers, but I need a favicon.ico file for older ones. The problem is that either the ICO format doesn't support semi-transaprency, which my favicon uses, or the converters I've found online don't support it.
Which is it? If the format supports it, how can I convert a PNG to an ICO with semi-transparency?