Does not respect user's fonts

[Gitoffthelawn]

Before submitting a bug report

• I updated to the latest version of Multi-Account Container and tested if I can reproduce the issue
• I searched for existing reports to see if it hasn't already been reported

Step to reproduce

The extension uses custom fonts instead of respecting the user's fonts.

This is a problem for multiple reasons, including:

1. Creates an unneeded accessibility issue
2. Violates user's expectations
3. Increases bloat (increases RAM usage, increases storage requirements, decreases Firefox launch performance)

Actual behavior

Uses custom fonts

Expected behavior

Respect the user's fonts

Additional informations

I will fix this issue via a PR shortly.

Provide a copy of Troubleshooting Information page (optional)

[Gitoffthelawn]

Fixed in PR #2892