Fix design patterns background

Author: philwareham

src/assets/sass/designpatterns.scss

@@ -13,6 +13,11 @@
    ONLY for use in design patterns - classes NOT USED in actual site builds.
    ========================================================================== */
 
+body {
+    background-color: $color-background;
+    color: $color-text;
+}
+
 main {
     padding: 0 5% 1em;