* Overlay-related fixes
- Prevent navigation when a folder's grid or list view is displayed in
an overlay;
* Overlay-related fixes
- Get rid of theme-based special overlay coloring that was making the
overlay hard to use;
- Add margin to `l-overlay-large` to make it clearer that user is in an
overlay when interacting with that view;
- Refinements to colors and layout in About screens;