As for your first problem…the header.
Yes, it would, it’s a very general CSS declaration and (for some reason) your test page is laid out with tables as the primary structure.
This is a very old method of layout and ‘frowned on’ these days by ‘professional’ web developers.
I’m assuming that this is something you can’t or won’t be able to get away from???
I’m also seeing
<br/> tags being used for spacing…another ‘old fashioned’ technique…margins/padding is what is used these days.