fixes styles so margin is included around code examples

Author: justinbmeyer

static/content.less

@@ -53,6 +53,7 @@ article {
   pre code {
     background: none;
     display: block;
+    margin: @gutter;
     word-wrap: break-word;
     font-size: 15px;
     line-height: 20px;

static/mixins.less

@@ -30,6 +30,7 @@
   box-shadow: @horizontal @vertical @blur @color;
 }
 .code {
+  .border-radius;
   background: @border-color;
   font-size: .9em;
   color: @code-color;