Include theme stylesheets after base theme stylesheets
In Tao's issue queue you will find more info. See Issue #1013440: TAO stylesheet loads last and overrides sub theme styles..

In the readme file:


  Tao does not use the all key for any of its stylesheets and expects
  that you will not either. Be specific - if the stylesheet is for the
  screen, or for print, say so. Any stylesheet overrides your subtheme
  provides should use the same media key as the one in tao.info for
  the stylesheet that is being overridden.