Difficulty Tabs And Table Header Don't Always Align

[otobot1]

Describe the bug
The right side of the right-most difficulty tab and the right side of the table header do not always line up.

To Reproduce
Steps to reproduce the behavior:

1. Go to /mods in Firefox.
2. Maximize the web browser on a 1080p display - the page needs to be a pretty specific width (see Image 1).
3. See error (see Image 2).

Expected behavior
The right-most difficulty tab and the right side of the mods table header should always line up.

Screenshots
1.

Desktop (please complete the following information):

• Browser: Confirmed in Firefox, unable to reproduce in Chrome

Additional context
May be related to #734. A fix for #734 could fix this issue as well.