diff --git a/normalize.css b/normalize.css
index 47b010e47..fa2fc4a0d 100644
--- a/normalize.css
+++ b/normalize.css
@@ -75,7 +75,7 @@ a {
  */
 
 abbr[title] {
-  border-bottom: none; /* 1 */
+  border-bottom: 0; /* 1 */
   text-decoration: underline; /* 2 */
   text-decoration: underline dotted; /* 2 */
 }