Just a small thing but it's been bugging me - the first and third columns in the "Allow role assignments", "Allow role overrides", and "Allow role switches" tabs under "Define Roles" are smaller than the other checkboxes (see screenshot).

The rogue style is in theme/standard/style/admin.css:

#page-admin-index .explanation,

.path-admin-roles .cell.c1,

.path-admin-roles .cell.c3 {font-size: 0.7em;}

Looks like the .path-admin-roles class is being used to style something else but isn't specific enough so it's being applied elsewhere.