Replaces hardcoded sidebar / nav-link hex colors with Bootstrap CSS
custom properties (var(--bs-dark), var(--bs-primary), var(--bs-gray-*),
var(--bs-white)). Visual parity preserved; rebrand/dark-mode work
later can override the variables without touching this file.
Only the reconnect overlay rgba(0,0,0,0.5) is left as a literal —
Bootstrap doesn't ship a backdrop-overlay token.
Joseph Doherty
eb1d6872ef