I have a theme using Adaptavist Theme Builder for Confluence, and I've encountered an issue where the theme is prefect in Firefox, Chrome or Safari but IE8 doesn't want to constrain the width of the table:
Example: http://wiki.bccampus.ca/pasbc
Turning on Compatibility mode doesn't help...
It's a three column layout, and the width of the middle column is fixed. Except on IE8... I've compared the output from Firebug in Chrome and Firefox, vs the Developer Tool in IE8 and I can't see a difference in the HTML.
Update
I attempted both of the CSS options provided, but wasn't seeing any change in the rendered element in IE. Then I found out the Theme Builder version was old, and need to upgrade to Confluence 3.3.x to use the newest version of Theme Builder...