Replace overflow: -moz-hidden-unscrollable with overflow: clip

chrome/linux_gtk_window_control_patch.css

@@ -13,7 +13,7 @@ See the above repository for updates as well as full license text. */
   fill: currentColor;
   padding: 4px 6px !important;
   flex-grow: 1;
-  overflow: -moz-hidden-unscrollable;
+  overflow: clip;
 }
 .titlebar-button:hover{ background-color: rgba(0,0,0,0.1) }
 .titlebar-min{ list-style-image: url(chrome://browser/skin/zoom-out.svg); }

chrome/multi-row_tabs_below_content.css

@@ -195,7 +195,7 @@ See the above repository for updates as well as full license text. */
   }
   .scrollbox-clip[orient="horizontal"],
   #tabbrowser-arrowscrollbox{
-    overflow: -moz-hidden-unscrollable;
+    overflow: clip;
     display: inline;
     --scrollbutton-display-model: none;
     --uc-scrollbox-max-height: calc((var(--tab-min-height) + 2 * var(--tab-block-margin,0px)) * var(--multirow-n-rows));

chrome/round_ui_items.css

@@ -27,7 +27,7 @@ button,
 .panel-arrowcontent{ margin-inline-end: 0 !important; }
 .panel-arrow{ margin-inline: 17px !important; }
 
-menupopup{ -moz-appearance: none !important; overflow: -moz-hidden-unscrollable !important; }
+menupopup{ -moz-appearance: none !important; overflow: clip !important; }
 
 .tabbrowser-tab[selected]::after,
 .tabbrowser-tab[beforeselected-visible]::after{ border-color: transparent !important; }

chrome/rounded_menupopups.css

@@ -11,7 +11,7 @@ menupopup,
 .panel-arrowcontent{
   -moz-appearance: none !important;
   border-radius: var(--uc-menupopup-border-radius) !important;
-  overflow: -moz-hidden-unscrollable !important;
+  overflow: clip !important;
 }
 
 /* The rounding is also applied to searchbar and urlbar to look consistent */