Isn't there a `border-radius` mixin, by the way? http://css-tricks.com/almanac/properties/b/border-radius/
```
/* Safari 3-4, iOS 1-3.2, Android 1.6- */
  -webkit-border-radius: 12px; 

  /* Firefox 1-3.6 */
  -moz-border-radius: 12px; 
  
  /* Opera 10.5, IE 9, Safari 5, Chrome, Firefox 4, iOS 4, Android 2.1+ */
  border-radius: 12px; 
```