If you make a banner that's bigger than the limit, even if it's only by a matter of pixels, then you should expect it to be cut off. The limits have been in place for ages.

It's only now that this button has been brought in that people are complaining - but if your sig isn't over the limit then it wouldn't be a problem...

But come on, is my banner that much over the limit? I could have three banners down there and 15 lines of text. That would be VERY over the limit.

Mine's hardly a rule breaking offence!

And someone said earlier that they'd rather spend their time changing other things on the site.. how come there's never a noticeable different? So they're changing discreet pointless things instead of what the members want. It's silly.

The limit is 550 x 350px. Yours is 512 x 412px, and so therefore it is 62px over the height limit.

Like it said, it's almost certainly automated. The script wont stop and think, "oh right, this banner is only a few pixels out so I'll let it off" - it will be programmed to hide anything that is over the limit, which in this case is 350px high.

EDIT: I'm wrong actually, the limit is 550 x 300px, so your banner is 112px over the limit.