Bug 1699673 - update Windows 10 proton context menu border and separator colours per UX feedback, r=jaws

Differential Revision: https://phabricator.services.mozilla.com/D109444

toolkit/themes/windows/global/global.css

@@ -41,7 +41,7 @@
     --menu-background-color: #f9f9fb;
     --menu-color: #15141a;
     --menu-disabled-color: rgba(21, 20, 26, 0.4);
-    --menu-border-color: #e0e0e6;
+    --menu-border-color: #cfcfd8;
     --menu-icon-opacity: 0.7;
 
     /* Declare menu colors for dark themes, but don't override anything yet. */
@@ -49,7 +49,7 @@
     --dark-menu-background-color: #2b2a33;
     --dark-menu-color: #fbfbfe;
     --dark-menu-disabled-color: rgba(251, 251, 254, 0.4);
-    --dark-menu-border-color: #52525e;
+    --dark-menu-border-color: #5b5b66;
     --dark-menu-icon-opacity: 1;
   }