Undoing this as it was buggy

Author: K4sum1

browser/themes/shared/r3dfox.css

@@ -2,7 +2,6 @@
 
 @media (-moz-bool-pref: "r3dfox.colors.enabled") {
   :root {
-    background: var(--in-content-page-background) !important;
     --arrowpanel-border-color: light-dark(rgb(255, 60, 60), rgb(155, 60, 60)) !important;
     --toolbar-field-focus-border-color: light-dark(rgb(255, 40, 40), rgb(155, 60, 60)) !important;
     --sidebar-border-color: light-dark(rgb(255, 60, 60), rgb(155, 60, 60)) !important;

toolkit/themes/shared/in-content/common-shared.css

@@ -217,7 +217,7 @@
 
 :root {
   appearance: none;
-  background-color: var(--in-content-page-background);
+  background: var(--in-content-page-background);
   color: var(--in-content-page-color);
 }