Best Practices - CSS

Hi everyone,

I've noticed at work that most DIV elements have to be over-written with a
new style sheet.
Such as:
<div class="main" style="width:85%; font-size:18pt;">

I don't think this is good practice since it's such a hack, but it works and
fixes the underlying layout problem.

Can anyone tell me what the best practice for over-writing existing CSS
styles?

-- 
Sze  Chan
sze.chan@acm.org

"DON'T BE ENCUMBERED BY HISTORY. GO OFF AND DO SOMETHING WONDERFUL. "
~Intel Co-Founder, Bob Noyce