diff --git a/css.html b/css.html
index 66bdd6df31..7a87598174 100644
--- a/css.html
+++ b/css.html
@@ -2075,7 +2075,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
 {% endhighlight %}
 {% highlight css %}
 // Mixin
-.clearfix {
+.clearfix() {
   &:before,
   &:after {
     content: " ";