Rework themes for parity with the old nav
Problem to solve
We've received numerous requests about missing the theme options available in the old navigation. These themes served as a simple way to distinguish GitLab from other webpages, and without them it can be hard to swap between different instances.
Proposal
Each available theme should have a distinct visual representation in the new navigation.
Implementation specs
Each of the colored theme will use a similar scale of color variables.
| Theme | Scale | Sidebar border color | 
|---|---|---|
| Gray | $gray-900/100/50 | $gray-950 8% | 
| Indigo | $t-indigo-900/100/50 | $gray-950 8% | 
| Light Indigo | $t-indigo-700/100/50 | $gray-950 8% | 
| Blue | $t-blue-900/100/50 | $gray-950 8% | 
| Light Blue | $t-light-blue-700/100/50 | $gray-950 8% | 
| Green | $t-green-900/100/50 | $gray-950 8% | 
| Light green | $t-green-700/100/50 | $gray-950 8% | 
| Red | $t-red-900/100/50 | $gray-950 8% | 
| Light Red | $t-light-red-700/100/50 | $gray-950 8% | 
Data
What does success look like, and how can we measure that?
Edited  by Austin Regnery

