[TYPO3-ect] Forcing a box to a certain width with CSS

[Ingmar Schlecht]

Hi guys,

is it possible with CSS to really force a box to only have a certain
width no matter what's inside it?

If so, it'd be cool if that CSS was applied to the "Upload comment:"
field of the latest extensions list at http://typo3.org/extensions/, so
the list never exceeds the page layout.

cheers,
Ingmar