Tweak TPAC header layout styles

The TPAC header relies heavily on fixed pixel measurements and relative
positioning, which makes it fragile and overly difficult to customize.

To improve the situation, we can greatly reduce the number of styles
while still achieving the same overall effect.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Dan Scott <dscott@laurentian.ca>