diff --git a/common/static/sass/_mixins.scss b/common/static/sass/_mixins.scss
index d0366485f8..509f9bd138 100644
--- a/common/static/sass/_mixins.scss
+++ b/common/static/sass/_mixins.scss
@@ -231,6 +231,7 @@
   border-radius: ($baseline/4);
   border: 1px solid $blue-l2;
   padding: 1px ($baseline/2) 2px ($baseline/2);
+  background-color: transparent;
   color: $blue-l2;
 
   &:hover, &:focus {