New clearfix syntax and add mixin reference : https://github.com/locomotivemtl/locomotive-boilerplate/issues/23

www/modules/boilerplate/assets/styles/src/tools/_tools.scss

@@ -14,4 +14,18 @@
 
 @function span($fraction) {
 	@return $fraction * 100%;
-}
+}
+
+/* Mixins
+   ========================================================================== */
+// Micro clearfix, as per {@link css-101.org/articles/clearfix/latest-new-clearfix-so-far.php CSS Mojo}
+//
+// @see inuitcss/generic.clearfix
+
+@mixin clearfix {
+	&:after {
+		content : "";
+		display : table;
+		clear   : both;
+	}
+}

www/modules/boilerplate/assets/styles/src/trumps/_helpers.scss

@@ -72,24 +72,13 @@
     visibility: hidden;
 }
 
-/*
- * Clearfix: contain floats
- *
- * 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 receive the `clearfix` class.
- * 2. The use of `table` rather than `block` is only necessary if using
- *    `:before` to contain the top-margins of child elements.
+/**
+ * Contain Floats
  */
-
-.clearfix:before,
-.clearfix:after {
-    content: " "; /* 1 */
-    display: table; /* 2 */
+%clearfix {
+	@include clearfix;
 }
 
-.clearfix:after {
-    clear: both;
+.clearfix {
+	@extend %clearfix;
 }