systemUsesDarkTheme -> RFP Alts

user.js

@@ -1439,7 +1439,7 @@ user_pref("privacy.firstparty.isolate", true);
       FF65: pointerEvent.pointerid (1492766)
  ** 1485266 - disable exposure of system colors to CSS or canvas (see 4615) (FF67+)
  ** 1407366 - enable inner window letterboxing (see 4504) (FF67+)
- ** 1540726 - return "light" with prefers-color-scheme (FF67+)
+ ** 1540726 - return "light" with prefers-color-scheme (see 4616) (FF67+)
       [1] https://developer.mozilla.org/en-US/docs/Web/CSS/@media/prefers-color-scheme
  ** 1564422 - spoof audioContext outputLatency (FF70+)
  ** 1595823 - spoof audioContext sampleRate (FF72+)
@@ -1569,6 +1569,9 @@ user_pref("dom.w3c_pointer_events.enabled", false);
   // [SETUP-CHROME] Might affect CSS in themes and extensions
   // [1] https://bugzilla.mozilla.org/buglist.cgi?bug_id=232227,1330876
 user_pref("ui.use_standins_for_native_colors", true);
+// 4616: enforce prefers-color-scheme as light [FF67+]
+  // 0=light, 1=dark : This overrides your OS value
+user_pref("ui.systemUsesDarkTheme", 0); // [HIDDEN PREF]
 // * * * /
 // ***/
 
@@ -1617,7 +1620,6 @@ user_pref("_user.js.parrot", "5000 syntax error: this is an ex-parrot!");
    // user_pref("browser.download.autohideButton", false); // [FF57+]
    // user_pref("toolkit.cosmeticAnimations.enabled", false); // [FF55+]
    // user_pref("toolkit.legacyUserProfileCustomizations.stylesheets", true); // [FF68+] allow userChrome/userContent
-   // user_pref("ui.systemUsesDarkTheme", 1); // [FF67+] override OS: 0=light, 1=dark
 /* CONTENT BEHAVIOR ***/
    // user_pref("accessibility.typeaheadfind", true); // enable "Find As You Type"
    // user_pref("clipboard.autocopy", false); // disable autocopy default [LINUX]