Bite-sized CSS & HTML nuggets

box-shadow vs filter: drop-shadow

This post is the first topic I discussed in my jam session presentation at Fronteers 2012. It’s about the drop-shadow filter. You may have looked at it and thought “this is pretty much the same thing as a box-shadow” right? Well, not exactly. The big advantage of the drop-shadow filter is that it acknowledges the outline and transparency of an element.

Have you ever wanted a box-shadow that followed the shape of an element, including generated content, like a tooltip with an arrow? Or you wanted a box-shadow to take transparent parts of a .png into account? That’s exactly what filter: drop-shadow() does. It has the exact same syntax as the box-shadow property, except that inset drop-shadows and the spread value are not supported (yet?).

Yes, it’s an experimental property, and yes, it’s only supported in some WebKit browsers now. But according to caniuse.com there’s already 32.51% of web users with support. And since it’s usually a decoration type of enhancement you can start using this today. Or even use a regular box-shadow on browsers that don’t support filters yet. Keep an eye on browser performance though, as things tend to get laggy pretty quickly with these experimental filters. Here’s a final example with a transparent PNG: