shorter clearfix

scss/mixins/_clearfix.scss

-// Clearfix
-//
-// For modern browsers
-// 1. The space content is one way to avoid an Opera bug when the
-//    contenteditable attribute is included anywhere else in the document.
-//    Otherwise it causes space to appear at the top and bottom of elements
-//    that are clearfixed.
-// 2. The use of `table` rather than `block` is only necessary if using
-//    `:before` to contain the top-margins of child elements.
-//
-// Source: http://nicolasgallagher.com/micro-clearfix-hack/
-
 @mixin clearfix() {
-  &:before,
-  &:after {
-    content: " "; // 1
-    display: table; // 2
-  }
   &:after {
+    content: "";
+    display: table;
     clear: both;
   }
 }