Summary: Coda is one of the new web development tools for the Mac - and it's popular amongst designers and developers I know. Panic (the developers of Coda) are also known for their sharp design. In particular, Jorge Mesa writes to ask how to re-create their 'puff' popup bubble shown when you mouse over the download image. In essence the effect is just a simple combination of effect, but there's a few nuances to be wary of.
