COMMONSSITE-82 Avoid repeated collapsed.gif


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/commons-skin/trunk@1676562 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/main/resources/css/site.css b/src/main/resources/css/site.css
index b74e318..0bb9ce2 100644
--- a/src/main/resources/css/site.css
+++ b/src/main/resources/css/site.css
@@ -7,7 +7,7 @@
 --------------------------------- */
 
 a.externalLink[href^="http"] {
-    background: none;
+    background-image: none;
 }
 
 #publishDate, #projectVersion, .divider {