Forgot 'default' color name

Lynesth · web-flow · commit dc3f0b5c8747 · 2018-05-07T22:35:53.000+11:00
diff --git a/src/Util/ColourUtil.php b/src/Util/ColourUtil.php
@@ -19,6 +19,7 @@ class ColourUtil
         'magenta',
         'cyan',
         'white',
+        'default',
     ];
 
     /**
