Problem: The Dimmer tool currently lightens all PDF content. While this works on a white background, it fails in Dark Mode. Instead of suppressing the background to make markups stand out, the Dimmer lightens the black background to grey. This creates a "grey fog" that reduces contrast and makes markups harder to see.
Suggested Fix: Make the Dimmer context-aware based on the active theme:
- In Light Mode: Continue lightening PDF content toward white.
- In Dark Mode: Darken PDF content toward black.
The goal is to ensure the background is always suppressed regardless of the theme, rather than washed out.
