[Tony G]

If you use the % width value in the Style Settings, it is the % of the whole screen that the table will take up. If the header stretches the table, that new space is counted in the % and the table stretches accordingly. Since your forum is not doing this, I would think that in your header code (possibly) your table is being set at a fixed width.

I may be wrong about this, as I've never had to solve this problem myself, but if you are sure you are using the % value for page width in the Style Settings and nothing in your code limiting the width, I'll look into this further.