--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -627,19 +627,17 @@ toolbar[brighttext] .toolbarbutton-1 > .
 }
 
 %include ../shared/menupanel.inc.css
 
 .findbar-button,
 #nav-bar .toolbarbutton-1,
 #nav-bar .toolbarbutton-1 > .toolbarbutton-menubutton-button {
   -moz-appearance: none;
-  border: none;
   padding: 0;
-  background: none;
 }
 
 #nav-bar .toolbarbutton-1:not([type=menu-button]),
 #nav-bar .toolbarbutton-1 > .toolbarbutton-menubutton-button,
 #nav-bar .toolbarbutton-1 > .toolbarbutton-menubutton-dropmarker {
   padding: var(--toolbarbutton-vertical-outer-padding) 2px;
   -moz-box-pack: center;
 }

--- a/toolkit/themes/windows/global/toolbarbutton.css
+++ b/toolkit/themes/windows/global/toolbarbutton.css
@@ -10,19 +10,17 @@
 
 /* ::::: toolbarbutton ::::: */
 
 toolbarbutton {
   -moz-appearance: toolbarbutton;
   -moz-box-align: center;
   -moz-box-pack: center;
   margin: 0;
-  border: 1px solid transparent;
   padding: 3px;
-  background-color: transparent;
   color: -moz-DialogText;
 }
 
 .toolbarbutton-icon[label]:not([label=""]),
 .toolbarbutton-icon[type="menu"] {
   margin-inline-end: 5px;
 }
 
@@ -38,24 +36,19 @@ toolbarbutton.tabbable {
 toolbarbutton:-moz-focusring {
   /* -moz-appearance looks redundant here but is necessary.
       Without it, the outline won't appear. */
   -moz-appearance: toolbarbutton;
   outline: 1px dotted -moz-DialogText;
   outline-offset: -2px;
 }
 
-toolbarbutton:hover:not([disabled="true"]) {
-  border-color: ThreeDHighlight ThreeDShadow ThreeDShadow ThreeDHighlight;
-}
-
 toolbarbutton:hover:active:not([disabled="true"]),
 toolbarbutton[open="true"]:hover,
 toolbarbutton[open="true"] {
-  border-color: ThreeDShadow ThreeDHighlight ThreeDHighlight ThreeDShadow;
   padding-top: 4px;
   padding-bottom: 2px;
   padding-inline-start: 4px;
   padding-inline-end: 2px;
 }
 
 toolbarbutton[disabled="true"] {
   color: GrayText;
@@ -65,22 +58,20 @@ toolbarbutton[disabled="true"] {
 @media (-moz-windows-classic) {
   toolbarbutton[disabled="true"] {
     color: ThreeDShadow;
     text-shadow: 1px 1px ThreeDHighlight;
   }
 }
 
 toolbarbutton[checked="true"]:not([disabled="true"]) {
-  border-color: ThreeDShadow ThreeDHighlight ThreeDHighlight ThreeDShadow;
   padding-top: 4px;
   padding-bottom: 2px;
   padding-inline-start: 4px;
   padding-inline-end: 2px;
-  background-color: rgba(255,255,255,0.5);
   color: ButtonText;
 }
 
 @media (-moz-windows-default-theme) {
   toolbarbutton:-moz-lwtheme {
     text-shadow: none;
   }
 
@@ -100,18 +91,16 @@ toolbarbutton[checked="true"]:not([disab
     text-shadow: inherit;
   }
 }
 
 /* ::::: toolbarbutton menu ::::: */
 
 .toolbarbutton-menu-dropmarker {
   -moz-appearance: none !important;
-  border: none !important;
-  background-color: transparent !important;
   padding: 0;
   width: auto;
   height: auto;
   margin-top: 1px;
 }
 
 /* ::::: toolbarbutton menu-button ::::: */
 
@@ -122,17 +111,16 @@ toolbarbutton[type="menu-button"] {
 
 toolbarbutton[type="menu-button"],
 toolbarbutton[type="menu-button"]:hover,
 toolbarbutton[type="menu-button"]:hover:active,
 toolbarbutton[type="menu-button"][open="true"],
 toolbarbutton[type="menu-button"][disabled="true"],
 toolbarbutton[type="menu-button"][disabled="true"]:hover,
 toolbarbutton[type="menu-button"][disabled="true"]:hover:active {
-  border-style: none;
   padding: 0 !important;
 }
 
 .toolbarbutton-menubutton-button {
   -moz-box-align: center;
   -moz-box-pack: center;
   -moz-box-orient: vertical;
 }
@@ -162,12 +150,10 @@ toolbarbutton[type="menu-button"][disabl
   -moz-stack-sizing: ignore;
 }
 
 /* .......... dropmarker .......... */
 
 .toolbarbutton-menubutton-dropmarker {
   -moz-appearance: none;
   padding: 3px 7px;
-  border: none;
-  background-color: transparent;
   width: auto;
 }