Display:inline w/Opera

Howdy,

I’ve been using display: inline to counter the double margin bug in IE - but doing so causes Opera 9 to display the inline element at 100% width.

http://icypenguin.ca/work/teetree/contact.php

The form and error fieldsets should be about 50% width each and floated beside each other. Works fine in everything but Opera.

I thought dislpay: inline worked for all browsers?