diff --git a/skin/classic/treestyletab/group.css b/skin/classic/treestyletab/group.css
index 1475e168..362f1886 100644
--- a/skin/classic/treestyletab/group.css
+++ b/skin/classic/treestyletab/group.css
@@ -52,8 +52,8 @@
 
 .background-image-container {
 	position: fixed;
-	top: auto;
+	top: 0;
 	right: 0;
 	bottom: 0;
-	left: auto;
+	left: 0;
 }