Whole forum in a <div> ??
 

Can this be done ?

I've set de main width off the forum at 100%.
Then added <div id="general"> on the first line off the header template and </div>
on the last line off the footer template.

Now if i set the width of the <div> at 90% nothing happens.

Did i do something wrong or is it just not possible ?

depends on what browser, the % is different in browsers. Ive had trouble with this in the past to get certain things to look the same in firefox and IE. Try setting a width to something small. See if it shrinks.