jellyfin sidemenu blur fallback for FF

CSS/themes/jellyfin/jellyfin-base.css

@@ -158,7 +158,8 @@ html {
 }
 
 
-.backgroundContainer:not(.backgroundContainer.withBackdrop), html {
+.backgroundContainer:not(.backgroundContainer.withBackdrop),
+html {
     background: var(--theme-background);
     background-repeat: repeat, no-repeat;
     background-attachment: fixed, fixed;
@@ -743,11 +744,24 @@ html {
     }
 }
 
+.mainDrawer {
+    background: var(--header-background);
+    background-repeat: repeat, no-repeat;
+    background-attachment: fixed, fixed;
+    background-position: center center, center center;
+    background-size: auto, cover;
+    -webkit-background-size: auto, cover;
+    -moz-background-size: auto, cover;
+    -o-background-size: auto, cover;
+}
+
+@supports (backdrop-filter: blur(1em)) or (-webkit-backdrop-filter:blur(1em)) {
     .mainDrawer {
         background: var(--header-blur-background);
         -webkit-backdrop-filter: saturate(1.8) blur(1.5em);
         backdrop-filter: saturate(1.8) blur(1.5em);
     }
+}
 
 .jstree-default .jstree-clicked {
     background: rgb(var(--accent-color));