FLUID-5299, FLUID-5314, FLUID-5301 - OverviewPanel bug fixes

Fixes for the following issues:
- FLUID-5299: OverviewPanel can appear offscreen and can't be scrolled.
- FLUID-5301: Transition effects are broken.
- FLUID-5314: Styling fixes.
- FLUID-5321: Missing icons when switching fonts
- FLUID-5322: There should be a border on the overview panel when using contrast themes