made preview button look more like Save buttons

assets/stylesheets/foreground.css

@@ -354,10 +354,10 @@ input[type="submit"] {
     transition: background-color 300ms ease-out;
 }
 
-input[type="button"] {
+input#wpPreview {
     background-color: #e9e9e9;
     border-color: #d0d0d0;
-    color: white;
+    color: black;
     -webkit-box-shadow: 0 1px 0 rgba(255, 255, 255, 0.5) inset;
     box-shadow: 0 1px 0 rgba(255, 255, 255, 0.5) inset;
     -webkit-transition: background-color 300ms ease-out;