When working on the diff theme support, the commit lists ended up with

a broken background color in light mode for the "-" and "+" operators.

This happened because a variable these depended on became an alpha

overlay color, rather than using a base color for insert/delete.
All the diff op colors have been updated to use base colors, ensuring

consistency there in both light and dark modes. The commits list has

also been updated to use a more correct font size in the process, so the

summary and message don't appear substantially larger than the

surrounding elements.
The standard file fields have been updated to match the same colors as

well, along with the same icons shown in the commit list and the same

padding. This helps bring consistency between the two elements. Right

now, these definitions are duplicated. Work needs to be done to build

CSS components for this part of the UI.

Tested several fields and the commit list in both light and dark modes.