You have to use a % values to put fixed tables on any resolution, the postbit and postbit_classic by default are inside a table, if you put any values like 300px, then in any resolution you have to show 300px in every part you can see.(on every place you use this value).
But if you put inside the contents a % value, you show the same results on many resolutions, well one is more big than another, but if you have 30% for one part and 70% to another, only on classic, because on normal mode, you see entire table xD.
If you show an account to see your template, you have to create a new account, then put the stylization with the problem by default and told us the user and pass, we check it and post the answer xD.
Well anyway i put one value to the right and one to the left to show what i want, or put a value as you want, but you have to review another value does not exist, because two or more declarations about the same thing, that is the problem xD.
Example:
<td class="trow1 usergroup{$post['usergroup']}" width="15%" valign="top" style="white-space: nowrap; text-align: center;"><a name="pid{$post['pid']}" id="pid{$post['pid']}">
Then on your CSS
.usergroup4{
width: 300px;
}
As you see you have two values for the same width value, you have to remove one of those vales, and make sure you have not another tr value with the same, because you make a conflict with that.
And other error i see you put appart of these an style value, you can put one value to all facts, onlye put the value to the entire stilization, then put an id value and finally put the stilization as you want, xD.