You extend the styles now you perhaps have:

  .mybutton
    /* all styles for Normal */
  .mybutton.skewed
    /* overrides for Skewed */
  .mybutton.disabled
    /* overrides for Disabled */

  class="mybutton skewed disabled"

The suggestion in the OP would be that each one of those classes contain all of the styles for the button. That isn't necessary. Plus it requires, what I count, a minimum of two additional language abstractions in order to do it.