Added support for css3 columns and updated readme

app/assets/stylesheets/css3/_columns.scss

@@ -0,0 +1,67 @@
+@mixin columns($arg: auto) {
+// <column-count> || <column-width>
+  -webkit-columns: $arg;
+     -moz-columns: $arg;
+          columns: $arg;
+}
+
+@mixin column-count($int: auto) {
+// auto || integer
+  -webkit-column-count: $int;
+     -moz-column-count: $int;
+          column-count: $int;
+}
+
+@mixin column-gap($length: normal) {
+// normal || length
+  -webkit-column-gap: $length;
+     -moz-column-gap: $length;
+          column-gap: $length;
+}
+
+@mixin column-fill($arg: auto) {
+// auto || length
+  -webkit-columns-fill: $arg;
+     -moz-columns-fill: $arg;
+          columns-fill: $arg;
+}
+
+@mixin column-rule($arg) {
+// <border-width> || <border-style> || <color>
+  -webkit-column-rule: $arg;
+     -moz-column-rule: $arg;
+          column-rule: $arg;
+}
+
+@mixin column-rule-color($color) {
+  -webkit-column-rule-color: $color;
+     -moz-column-rule-color: $color;
+          column-rule-color: $color;
+}
+
+@mixin column-rule-style($style: none) {
+// none | hidden | dashed | dotted | double | groove | inset | inset | outset | ridge | solid
+  -webkit-column-rule-style: $style;
+     -moz-column-rule-style: $style;
+          column-rule-style: $style;
+}
+
+@mixin column-rule-width ($width: none) {
+  -webkit-column-rule-width: $width;
+     -moz-column-rule-width: $width;
+          column-rule-width: $width;
+}
+
+@mixin column-span($arg: none) {
+// none || all
+  -webkit-column-span: $arg;
+     -moz-column-span: $arg;
+          column-span: $arg;
+}
+
+@mixin column-width($length: auto) {
+// auto || length
+  -webkit-column-width: $length;
+     -moz-column-width: $length;
+          column-width: $length;
+}

readme.md

@@ -161,6 +161,13 @@ Box-sizing will change the box-model of the element it is applied to.
 
     @include box-sizing(border-box);
 
+### Columns
+
+All current CSS3 column properties are supported. See the list at the bottom of the page for more info.
+
+    @include columns(12 8em);
+    @include column-rule(1px solid green);
+
 
 ### Flex Box
 
@@ -407,6 +414,18 @@ These CSS cubic-bezier timing functions are variables that can be used with CSS3
       @ box-shadow(*args)
       @ box-sizing(*args)
 
+      columns
+        @columns(*args)
+        @column-count(*args)
+        @column-fill(*args)
+        @column-gap(*args)
+        @column-rule(*args)
+          @column-rule-color(*args)
+          @column-rule-style(*args)
+          @column-rule-width(*args)
+        @column-span(*args)
+        @column-width(*args)
+
       flex-box
         @ box(*args)
         @ box-align(*args)