Move into assets folder

assets/scss/utilities/_mixins.scss

@@ -0,0 +1,60 @@
+/*
+ * Media query to respond to a minimum size (mobile first)
+ */
+
+@mixin resp-min($size) {
+  @media screen and (min-width: $size) { 
+    @content; 
+  }
+}
+
+
+/*
+ * Media query to respond to a maximum size
+ */
+
+@mixin resp-max($size) {
+  @media screen and (max-width: $size) { 
+    @content; 
+  }
+}
+
+
+/*
+ * Output font size in px/rem
+ */
+
+@mixin font-size($px) {
+  font-size: $px + px;
+  font-size: #{$px / $base-font-size}rem;
+}
+
+
+/*
+ * Placeholder mixin for <input>
+ */
+
+@mixin placeholder() {
+  $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input";
+  @each $placeholder in $placeholders {
+    &:#{$placeholder}-placeholder {
+      @content;
+    }
+  }
+}
+
+
+/**
+ * Clearfix
+ */
+
+@mixin clearfix() {
+  &:before,
+  &:after{
+    content: " ";
+    display: table;
+  }
+  &:after{
+    clear: both;
+  }
+}