Bug 1741815 - Don't override lightweight theme colors in HCM. r=desktop-theme-reviewers,dao

Differential Revision: https://phabricator.services.mozilla.com/D131494

browser/themes/windows/browser-aero.css

@@ -67,12 +67,12 @@
 
       /* See bug 1715990 about why we do this ourselves on HCM */
       @media (prefers-contrast) {
-        :root[tabsintitlebar] {
+        :root[tabsintitlebar]:not(:-moz-lwtheme) {
           background-color: ActiveCaption;
           color: CaptionText;
         }
 
-        :root[tabsintitlebar]:-moz-window-inactive {
+        :root[tabsintitlebar]:not(:-moz-lwtheme):-moz-window-inactive {
           background-color: InactiveCaption;
           color: InactiveCaptionText;
         }