The mod modifies the templates so page content is loaded inside a div instead of a table. This separates the page header from page content allowing the header to stay on the page when content overflows. The two new files copied to each template are smtopmenu.php and smfooter.php. The mod also adds a few classes to the existing templatestyle.css file for each template.
When the mod is first installed, pages will remain the same until the Custom Header and Custom Footer are changed.
To use the new files go to TNG admin. Select Setup -> General Settings -> Site Design and Definition
Change topmenu.php to smtopmenu.php
Change footer.php to smfooter.php
Each header/footer combination are sets so if you change one and not the other the header or footer may not appear.
This is template 2 when a wide chart is displayed:

This is template 2 after installing the mod and changing the topmenu and footer file names.

This is template 6 when a wide chart is displayed:

This is template 6 after installing the mod and changing the topmenu and footer file names.

for TNG v14.0.3
TNG WIKI download link
Revisions:
25 Nov 2023 - Removed script in template 4 to align divs
If you are unhappy with the results, simply reverse the installation procedure and delete the mod.