Is there really any point to using relative font sizing in CSS?

Question

I've read a lot about the pros and cons of sizing with either relative or absolute font sizes. Fixed sizes don't zoom in IE6 but that's not much of an issue these days. Accessibility is important, but I assume that all good accessibility software is built to deal with these issues?

I guess it mainly comes down to whether you want to be able to change all font sizes with one rule (i.e. the default font size you set) or whether you want to be able to change a font size somewhere without affecting nested elements (this is the thing that frustrates me most!).

Anyone have any tips?

Answer 1

According to YUI Font CSS,

Always use percentages as the units because they render more consistently than ems, and because they allow user-initiated resizing (unlike pixels).

Relative font sizes work pretty well when they are part of a framework like YUI. Especially because they normalize how fonts work across browsers.

Personally, I do throw in absolute px every once in a while, but typically only for text that must somehow match up size-wise with some other design elements (like a menu).

The % stuff does break down when you assign % to a certain element and then a different % to a contained element. But that's the only real gotcha I've found.