Here's the data:
having fonts of specified size, lines of specified heights, when viewed in browser's default font-size (i mean, when the user hasn't triggered the size of the fonts manually to set them bigger or smaller).
+ allowing the user to make the fonts bigger or smaller with the browser, and keeping the same kind of line-height (ie, a text whose size has been x3 would see its line-height being x3 too)

Here's the solution:
using CSS attributes in EMS. like { font-size:0.9ems; line-height:1.4ems }

Here's the problem:
this works fine in NS, but not in IE (even in 5.5).

I must say i was really happily surprised to see NS4 being more standards-compliant than IE5.5 on this matter.

But it still is a problem, as we can have old visitors coming and resizing the fonts, thus making them all tangled up if the line-height isn't resized too.

So, any way to get around this problem ? Anything better than EM on this ?
Any help or just a glimpse of an answer would be greatly appreciated, as i imagine cross-browsers masters are lurking here.