diff --git a/chrome.manifest b/chrome.manifest
index b338b7b5..7a2d502e 100644
--- a/chrome.manifest
+++ b/chrome.manifest
@@ -16,3 +16,5 @@ locale	treestyletab	zh-TW	jar:chrome/treestyletab.jar!/locale/zh-TW/treestyletab
 locale	treestyletab	ru-RU	jar:chrome/treestyletab.jar!/locale/ru-RU/treestyletab/
 
 skin	treestyletab	classic/1.0	jar:chrome/treestyletab.jar!/skin/classic/treestyletab/
+
+style chrome://browser/content/browser.xul chrome://treestyletab/skin/treestyletab-3.1.css appversion>=3.1b3pre
diff --git a/skin/classic/treestyletab/dropshadow.png b/skin/classic/treestyletab/dropshadow.png
new file mode 100644
index 00000000..e03cc718
Binary files /dev/null and b/skin/classic/treestyletab/dropshadow.png differ
diff --git a/skin/classic/treestyletab/treestyletab-3.1.css b/skin/classic/treestyletab/treestyletab-3.1.css
new file mode 100644
index 00000000..3020c299
--- /dev/null
+++ b/skin/classic/treestyletab/treestyletab-3.1.css
@@ -0,0 +1,20 @@
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+
+/* Shadow of vertival tabs */
+
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="default"] .tabbrowser-tab,
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="mixed"] .tabbrowser-tab {
+	-moz-box-shadow: -5px 0 5px rgba(0, 0, 0, 0.15) !important;
+}
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="default"][treestyletab-appearance-inverted="true"] .tabbrowser-tab,
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="mixed"][treestyletab-appearance-inverted="true"] .tabbrowser-tab {
+	-moz-box-shadow: 5px 0 5px rgba(0, 0, 0, 0.15) !important;
+}
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="default"]:not([treestyletab-hide-newtab-button]) .tabs-container:not([overflow="true"]) .scrollbox-innerbox,
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="mixed"]:not([treestyletab-hide-newtab-button]) .tabs-container:not([overflow="true"]) .scrollbox-innerbox {
+	background: url("dropshadow.png") repeat-x bottom !important;
+}
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="default"]:not([treestyletab-hide-newtab-button="true"]) .tabs-container:not([overflow="true"]) .tabbrowser-arrowscrollbox .tabs-newtab-button,
+tabbrowser[treestyletab-mode="vertical"][treestyletab-style="mixed"]:not([treestyletab-hide-newtab-button="true"]) .tabs-container:not([overflow="true"]) .tabbrowser-arrowscrollbox .tabs-newtab-button {
+	margin-bottom: 5px !important;
+}
diff --git a/skin/classic/treestyletab/treestyletab.css b/skin/classic/treestyletab/treestyletab.css
index bfbb9d25..ec85dd5b 100644
--- a/skin/classic/treestyletab/treestyletab.css
+++ b/skin/classic/treestyletab/treestyletab.css
@@ -276,8 +276,6 @@ tabbrowser[treestyletab-tabbar-position="bottom"][treestyletab-style="mixed"] .t
 }
 
 
-
-
 /* Tree UI */
 
 .treestyletab-twisty-container {
@@ -477,4 +475,3 @@ tabbrowser[treestyletab-tabbar-transparent] .tabbrowser-tabs:hover .tabbrowser-t
 tabbrowser[treestyletab-tabbar-transparent] .tabbrowser-tabs:hover .tabbrowser-tab[selected="true"]:hover {
 	opacity: 0.98 !important;
 }
-