Forum width issue
 

I have a custom HTML header and it changes its size on different screen resolutions..
my problem is that my forum width doesn't always match the width of my custom HTML header..
they only match in one screen resolution (1366 x 768)

You must have the fluid wrapper width in %, change the doc_width to perhaps same size as header in px.

That depend of the forum width then, check at the stylevar: doc_width and see if it's at 100% that's fluid, you can change it to whatever value in pixels you want.

Also if you've added the doc_width as fixed check the doc_margin and add the left and right values to auto to have the fixed page just like the vB.org fixed one.

And finally, if that doesn't work, then please check the header items because that would be the problem.

Rafael