Horizontal scrollbars remain white in dark mode

Description

Horizontal scrollbars remain white in dark mode.

To Reproduce…

Steps to reproduce the behavior:

  1. Activate dark mode
  2. Receive an email whose width is greater than panel width

Expected Behavior

Expected horizontal scrollbars to be dark in dark mode.

Screenshots

Setup

  • OS and Version: Linux Mint 20
  • Mailspring Version: 1.7.8

Additional Context