Further menu improvements

Author: K4sum1

toolkit/themes/shared/menu-shared.css

@@ -108,7 +108,6 @@ menuitem {
     text-shadow: none;
   }
 
-@media (-moz-windows-non-native-menus) {
   &:where([_moz-menuactive]:not([disabled="true"])) {
     color: -moz-menuhovertext;
     background-color: -moz-menuhover;
@@ -118,7 +117,6 @@ menuitem {
     background-color: -moz-menuhoverdisabled;
   }
 }
-}
 
 @media (-moz-windows-classic) {
   menu[disabled="true"],

toolkit/themes/shared/menulist-shared.css

@@ -51,18 +51,15 @@
 dropmarker {
   pointer-events: none;
   flex: 0;
-  align-self: center;
 }
 
 dropmarker:not([native]) {
   display: flex;
   appearance: none;
-}
-
-dropmarker:not([native])::part(icon) {
   content: url(chrome://global/skin/icons/arrow-down-12.svg);
   -moz-context-properties: fill;
   fill: currentColor;
+  align-self: center;
 }
 
 #highlightable-label:not([highlightable="true"]),

toolkit/themes/shared/popup.css

@@ -45,6 +45,12 @@ panel {
   @media (-moz-platform: linux) or (-moz-platform: windows) {
     /* To account for the box-shadow below */
     --panel-shadow-margin: 4px;
+
+    @media not (-moz-windows-non-native-menus) {
+      --panel-shadow: 0 0 var(--panel-shadow-margin) hsla(0,0%,0%,.2);
+      -moz-window-input-region-margin: var(--panel-shadow-margin);
+      margin: calc(-1 * var(--panel-shadow-margin));
+    }
   }
 
   /* On some linux WMs we need to draw square menus because alpha is not available */
@@ -97,9 +103,8 @@ panel {
 
 menupopup {
   /* Also apply the padding in the inline axis for menus */
+@media (-moz-windows-non-native-menus) or (-moz-platform: linux) {
   --panel-padding: var(--panel-padding-block);
-
-@media (-moz-windows-non-native-menus) {
   @media (-moz-platform: windows) {
     > menu,
     > menuitem {
@@ -227,6 +232,14 @@ panel:where([type="arrow"]) {
   }
 }
 
+@media (-moz-platform: windows) {
+  menulist > menupopup {
+    appearance: none;
+    background-color: transparent;
+    border: none;
+  }
+}
+
 @media not (-moz-windows-non-native-menus) {
   /* For Win10, the popup itself needs to have a transparent background because
      otherwise the background color would appear behind the drop shadow. */