diff --git a/platform/Linux/chrome.manifest b/platform/Linux/chrome.manifest
index 165e5c54..8a9d4e7f 100644
--- a/platform/Linux/chrome.manifest
+++ b/platform/Linux/chrome.manifest
@@ -1 +1,3 @@
 skin	treestyletab-platform	classic/1.0	jar:chrome/treestyletab.jar!/skin/classic/treestyletab/
+
+style chrome://browser/content/browser.xul chrome://treestyletab-platform/skin/treestyletab-3.1.css appversion>=3.1b3pre
diff --git a/platform/Linux/skin/classic/treestyletab/treestyletab-3.1.css b/platform/Linux/skin/classic/treestyletab/treestyletab-3.1.css
new file mode 100644
index 00000000..3cd7526b
--- /dev/null
+++ b/platform/Linux/skin/classic/treestyletab/treestyletab-3.1.css
@@ -0,0 +1,6 @@
+@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
+
+tabbrowser[treestyletab-mode="vertical"][treestyletab-tabbar-dropshadow="true"]:not([treestyletab-style="vertigo"])
+	.tabbrowser-tab {
+	z-index: auto;
+}