Comment 4 for bug 1740529

For roadmap planning purposes, here are the dominoes that have to fall into place for us to have a dark mode (or multiple color schemes).

Bootstrap 5.3 includes a color scheme toggle feature: https://getbootstrap.com/docs/5.3/customize/color-modes/

We will get 5.3 as part of ng-bootstrap 16, which depends on Angular 17. It's not out yet; here's the roadmap: https://github.com/ng-bootstrap/ng-bootstrap/milestone/134

In addition to those upgrades, we will need to move all our colors to variables (bug 2023449) and switch from CSS to Sass (bug 2030516).