Use light page background for text layouts

patterns/text-layouts.html

@@ -6,7 +6,7 @@
   <title>Styleguide – Pattern Text Layouts</title>
   <link rel="stylesheet" href="../styleguide.css">
 </head>
-<body>
+<body class="sg-page-text-layouts">
 
   <h1 class="sg-main-heading">Pattern – Text Layouts</h1>
   <section id="pattern-text-layouts">