Bug fixes and improvements.

Changes:

Added coloring for spoilers.
Improved look and feel of settings checkboxes.
Tidied up theme files.
Divider changes:
- New divider-thickness variable, default is 3px. (scales)
- Removed unnecessary padding for 'New' text.
Bugs fixed:
- Bot tag checkmark coloring.
- Fullscreen VC chat spacing.
- Incorrect dnd color listed in theme files.
- Multiple discovery page fixes, including: spacing, color, and roundness.
- Incorrect default dnd color in theme files.
- Flickering on settings checkboxes.