I'm all for relative text sizes.

For web designers, there are a couple of issues.

One way of doing relative text sizes is to set the CSS font-size to xx-small, x-small, small, medium, large, x-large, or xx-large.

The trouble with that is that IE displays those one size too small.

Another way is to use em's or percentages.

But some browsers make those relative to the default size, instead of to the size in the parent element.

Lastly, there's 'larger' and 'smaller', but you can imagine that those would be insufficient for the desires of many web designers.

Thus, most turn to absoluter pixels sizes. It's not good, it's not right, and it's contrary to W3C suggestions, but there is a rationale for it.

Want this to stop being a problem? Tell your friends who use older browsers to upgrade to modern browsers that support these correctly.

[Note that is spite of what I said here, I voted 'for'.]