diff --git a/skin/classic/treestyletab/Linux-base.css b/skin/classic/treestyletab/Linux-base.css
index 04ba193e..701f5d67 100644
--- a/skin/classic/treestyletab/Linux-base.css
+++ b/skin/classic/treestyletab/Linux-base.css
@@ -2,7 +2,6 @@
 
 /* splitter for floating & autohide tab bar */
 .treestyletab-tabbar-toolbar .treestyletab-splitter {
-	appearance: none;
 	-moz-appearance: none;
 	width: 6px;
 }
diff --git a/skin/classic/treestyletab/base.css b/skin/classic/treestyletab/base.css
index 0240a53c..3563df52 100644
--- a/skin/classic/treestyletab/base.css
+++ b/skin/classic/treestyletab/base.css
@@ -42,7 +42,6 @@
 .tabbrowser-tabs[treestyletab-mode="vertical"] .tabs-newtab-button,
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"] > toolbarbutton,
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"] > toolbarpaletteitem > toolbarbutton {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: 0 none !important;
 	-moz-border-top-colors: none !important;
@@ -75,7 +74,6 @@
 
 /* Support customizable tab bar */
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"] > toolbarpaletteitem > toolbarbutton {
-	box-flex: 1;
 	-moz-box-flex: 1;
 }
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"] > *:not(toolbarpaletteitem) {
diff --git a/skin/classic/treestyletab/config.css b/skin/classic/treestyletab/config.css
index b954604f..859d7ac7 100644
--- a/skin/classic/treestyletab/config.css
+++ b/skin/classic/treestyletab/config.css
@@ -2,7 +2,6 @@
 
 radio.image .radio-label-box,
 radio.image label.radio-label {
-	box-align: center;
 	-moz-box-align: center;
 }
 
diff --git a/skin/classic/treestyletab/group.css b/skin/classic/treestyletab/group.css
index f13d8151..756c3bb5 100644
--- a/skin/classic/treestyletab/group.css
+++ b/skin/classic/treestyletab/group.css
@@ -1,7 +1,6 @@
 @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
 
 :root {
-	appearance: window;
 	-moz-appearance: window;
 	background: -moz-dialog;
 	margin: 0;
@@ -60,7 +59,6 @@
 #tree {
 	margin: 1em 0 0 0.5em;
 	overflow: auto;
-	box-flex: 1;
 	-moz-box-flex: 1;
 }
 
diff --git a/skin/classic/treestyletab/metal/aero.css b/skin/classic/treestyletab/metal/aero.css
index b364a489..8714f639 100644
--- a/skin/classic/treestyletab/metal/aero.css
+++ b/skin/classic/treestyletab/metal/aero.css
@@ -5,7 +5,6 @@
 tabbrowser[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]),
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #appcontent,
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #browser {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 }
diff --git a/skin/classic/treestyletab/metal/base.css b/skin/classic/treestyletab/metal/base.css
index b4d13c82..f58315e9 100644
--- a/skin/classic/treestyletab/metal/base.css
+++ b/skin/classic/treestyletab/metal/base.css
@@ -4,7 +4,6 @@
 
 .treestyletab-tabbar-toolbar:not([treestyletab-tabbar-position="top"]),
 .treestyletab-tabbar-toolbar[treestyletab-tabbar-position="top"]:not([treestyletab-tabbar-fixed="true"]) {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 	border: 0 none !important;
@@ -41,7 +40,6 @@
 }
 
 .tabbrowser-tabs[treestyletab-mode="vertical"] {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 	margin: 0;
@@ -77,7 +75,6 @@ tabbrowser[treestyletab-mode="vertical"]
   .treestyletab-splitter,
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"]
   .treestyletab-splitter {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: #b3b2b3 !important;
 	border: 0 solid #666666 !important;
diff --git a/skin/classic/treestyletab/metal/tab.css b/skin/classic/treestyletab/metal/tab.css
index 03ed5d9a..05546d3a 100644
--- a/skin/classic/treestyletab/metal/tab.css
+++ b/skin/classic/treestyletab/metal/tab.css
@@ -8,7 +8,6 @@
   .tabbrowser-tab[visuallyselected="true"],
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tabbrowser-tab[visuallyselected="true"]:hover {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: 2px solid transparent !important;
 	border-radius: 0 !important;
@@ -112,7 +111,6 @@
 }
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tab-content {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: 10px solid transparent;
 	margin: 0 !important;
diff --git a/skin/classic/treestyletab/sidebar/aero.css b/skin/classic/treestyletab/sidebar/aero.css
index 3cb6e067..ec91a63e 100644
--- a/skin/classic/treestyletab/sidebar/aero.css
+++ b/skin/classic/treestyletab/sidebar/aero.css
@@ -5,7 +5,6 @@
 tabbrowser[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]),
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #appcontent,
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #browser {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 }
diff --git a/skin/classic/treestyletab/sidebar/sidebar.css b/skin/classic/treestyletab/sidebar/sidebar.css
index 05b921e3..dfd20cc9 100644
--- a/skin/classic/treestyletab/sidebar/sidebar.css
+++ b/skin/classic/treestyletab/sidebar/sidebar.css
@@ -108,7 +108,6 @@ tabbrowser[treestyletab-mode="vertical"]
 /* Style tabs themselves.  Get rid of most of the initial XUL styling */
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tabbrowser-tab {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: none;
 	border-radius: 0 !important;
diff --git a/skin/classic/treestyletab/square/base.css b/skin/classic/treestyletab/square/base.css
index 341baddf..2ba259c8 100644
--- a/skin/classic/treestyletab/square/base.css
+++ b/skin/classic/treestyletab/square/base.css
@@ -31,14 +31,12 @@
 
 .tabbrowser-tabs:not([treestyletab-tabbar-position="top"]),
 .treestyletab-tabbar-toolbar:not([treestyletab-tabbar-position="top"]) {
-	appearance: none;
 	-moz-appearance: none;
 	background: transparent !important;
 	margin: 0 !important;
 	padding: 0 !important;
 }
 .tabbrowser-strip[treestyletab-style~="border"]:not([treestyletab-tabbar-position="top"]) {
-	appearance: none;
 	-moz-appearance: none;
 	background: var(--tst-tabbar-bg) !important;
 }
@@ -113,7 +111,6 @@
   .tabbrowser-tab[visuallyselected="true"],
 .tabbrowser-tabs:not([treestyletab-tabbar-position="top"])
   .tabbrowser-tab:not([visuallyselected="true"]) {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	min-height: 2em;
 	margin: 0 !important;
@@ -129,7 +126,6 @@
 	border-radius: 0 !important;
 	-moz-border-image: none !important;
 	border-image: none !important;
-	box-align: stretch !important;
 	-moz-box-align: stretch !important;
 }
 /* override "-moz-menutext" color defined by the default theme, because it is too bright on Ubuntu */
@@ -295,7 +291,6 @@
 /* Mac OS X */
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tabbrowser-tab {
-	box-pack: start !important;
 	-moz-box-pack: start !important;
 	text-align: start !important; 
 }
@@ -324,7 +319,6 @@
 tabbrowser[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]),
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #appcontent,
 :root[treestyletab-style~="aero"]:not([treestyletab-tabbar-position="top"]) #browser {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 }
diff --git a/skin/classic/treestyletab/tmp.css b/skin/classic/treestyletab/tmp.css
index bf03a25b..167d7f9e 100644
--- a/skin/classic/treestyletab/tmp.css
+++ b/skin/classic/treestyletab/tmp.css
@@ -38,7 +38,6 @@
 
 :root[treestyletab-enable-compatibility-tmp="true"]
   .tabbrowser-tabs[treestyletab-mode="vertical"] .tabs-closebutton-topbox > .tabs-closebutton {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: 0 none !important;
 	-moz-border-top-colors: none !important;
@@ -66,13 +65,9 @@
 
 :root[treestyletab-enable-compatibility-tmp="true"]
   .tabbrowser-tabs[treestyletab-mode="vertical"] .tabs-newtab-topbox > .tabs-newtab-button {
-	box-flex: 1;
 	-moz-box-flex: 1;
-	box-align: center;
 	-moz-box-align: center;
-	box-pack: center;
 	-moz-box-pack: center;
-	box-orient: vertical;
 	-moz-box-orient: vertical;
 }
 
diff --git a/skin/classic/treestyletab/twisty/twisty.css b/skin/classic/treestyletab/twisty/twisty.css
index 2d4bd790..2b30bb41 100644
--- a/skin/classic/treestyletab/twisty/twisty.css
+++ b/skin/classic/treestyletab/twisty/twisty.css
@@ -12,11 +12,8 @@
 	max-width: 16px;
 	min-height: 16px;
 	min-width: 16px;
-	box-pack: start;
 	-moz-box-pack: start;
-	box-align: center;
 	-moz-box-align: center;
-	box-flex: 1;
 	-moz-box-flex: 1;
 }
 
diff --git a/skin/classic/treestyletab/ui-base.css b/skin/classic/treestyletab/ui-base.css
index ad87d301..3b730f06 100644
--- a/skin/classic/treestyletab/ui-base.css
+++ b/skin/classic/treestyletab/ui-base.css
@@ -3,9 +3,7 @@
 /* tree UI */
 
 .treestyletab-counter-container {
-	box-align: center;
 	-moz-box-align: center;
-	box-pack: end;
 	-moz-box-pack: end;
 }
 
@@ -165,7 +163,6 @@
 
 
 tabbrowser[treestyletab-drop-position] {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	border: 2px solid transparent !important;
 	-moz-border-top-colors: none !important;
@@ -306,7 +303,6 @@ tabbrowser[treestyletab-tabbar-position="bottom"]
 /* toolbar customization */
 
 .treestyletab-tabbar-toolbar-ready-popup {
-	appearance: tooltip;
 	-moz-appearance: tooltip;
 	max-width: 15em;
 	opacity: 0.85;
@@ -343,18 +339,14 @@ tabbrowser[treestyletab-tabbar-position="bottom"]
   .tabbrowser-tab[pinned="true"] .tab-stack,
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tab-content[pinned="true"] {
-	box-align: center;
 	-moz-box-align: center;
-	box-pack: center;
 	-moz-box-pack: center;
 	min-height: 0;
 }
 
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tab-background[pinned="true"] {
-	box-align: stretch;
 	-moz-box-align: stretch;
-	box-pack: justify;
 	-moz-box-pack: justify;
 	min-height: 0;
 }