diff --git a/content/treestyletab/treestyletab-tmp.css b/content/treestyletab/treestyletab-tmp.css
index 8f6b96af..3e46a446 100644
--- a/content/treestyletab/treestyletab-tmp.css
+++ b/content/treestyletab/treestyletab-tmp.css
@@ -21,7 +21,6 @@
 
 :root[treestyletab-enable-compatibility-tmp="true"]
   tabbrowser[treestyletab-mode="vertical"] tabs[flowing] > * .tabs-frame {
-	box-flex: 1 !important;
 	-moz-box-flex: 1 !important;
 }
 
diff --git a/content/treestyletab/treestyletab.css b/content/treestyletab/treestyletab.css
index 7413cbdf..c27e3691 100644
--- a/content/treestyletab/treestyletab.css
+++ b/content/treestyletab/treestyletab.css
@@ -60,7 +60,6 @@
 	max-width: 20px;
 	min-width: 20px;
 	width: 20px;
-	box-flex: 0;
 	-moz-box-flex: 0;
 	mask: url("res/tabEffects.svg#fadein-mask");
 }
@@ -171,7 +170,6 @@ tabbrowser[treestyletab-tabbar-autohide-mode="1"][treestyletab-tabbar-autohide="
 
 
 #treestyletab-autohide-content-area-screen {
-	appearance: none;
 	-moz-appearance: none;
 	/**
 	 * Don't make this panel completely transparent, because
@@ -202,9 +200,7 @@ tabbrowser[treestyletab-tabbar-autohide-mode="1"][treestyletab-tabbar-autohide="
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tabbrowser-arrowscrollbox
   .scrollbox-innerbox {
-	box-flex: 1 !important;
 	-moz-box-flex: 1 !important;
-	box-pack: start !important;
 	-moz-box-pack: start !important;
 }
 
@@ -218,7 +214,6 @@ toolbar.treestyletab-tabbar-toolbar[treestyletab-mode="vertical"]
   > toolbaritem,
 toolbar.treestyletab-tabbar-toolbar[treestyletab-mode="vertical"]
   > .treestyletab-toolbar-inner-box > toolbaritem {
-	box-flex: 0 !important;
 	-moz-box-flex: 0 !important;
 }
 
@@ -229,7 +224,6 @@ toolbar.treestyletab-tabbar-toolbar[treestyletab-mode="vertical"]
 
 /* workaround for https://github.com/piroor/treestyletab/issues/100 */
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"] .textbox-input-box {
-	box-align: stretch;
 	-moz-box-align: stretch;
 }
 
@@ -421,7 +415,6 @@ toolbar.treestyletab-tabbar-toolbar-ready:not([nowindowdrag="true"]),
 
 .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;
 	line-height: 0 !important; /* to avoid an useless space above the tab bar */
 	position: fixed !important;
diff --git a/skin/classic/treestyletab/sidebar/sidebar.css b/skin/classic/treestyletab/sidebar/sidebar.css
index dfd20cc9..1e2c159e 100644
--- a/skin/classic/treestyletab/sidebar/sidebar.css
+++ b/skin/classic/treestyletab/sidebar/sidebar.css
@@ -112,7 +112,6 @@ tabbrowser[treestyletab-mode="vertical"]
 	border: none;
 	border-radius: 0 !important;
 	border-top: 1px solid transparent !important;
-	box-align: stretch !important;
 	-moz-box-align: stretch !important;
 	height: 21px !important;     /* height including border! */
 	margin: 0 !important;
@@ -330,7 +329,6 @@ tabbrowser[treestyletab-mode="vertical"]
 
 .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;
@@ -358,7 +356,6 @@ tabbrowser[treestyletab-mode="vertical"]
 .treestyletab-tabbar-toolbar[treestyletab-mode="vertical"]
   > toolbarpaletteitem
   > toolbarbutton:hover {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 	border: 0 none !important;
@@ -394,7 +391,6 @@ tabbrowser[treestyletab-mode="vertical"]
 	-moz-image-region: auto !important;
 }
 .tabbrowser-tabs[treestyletab-mode="vertical"] {
-	appearance: none !important;
 	-moz-appearance: none !important;
 	background: transparent !important;
 	margin: 0;
@@ -403,7 +399,6 @@ tabbrowser[treestyletab-mode="vertical"]
 /* for Linux (Gnomestrip) */
 .tabbrowser-tabs[treestyletab-mode="vertical"]
   .tab-close-button {
-	appearance: none !important;
 	-moz-appearance: none !important;
 }