Possible to hide admin toolbar for testing display
If your using the built in D7 tool bar, take a look at Toolbar Hider.


  This module will hide/show the toolbar with the press of a key that
  you configure. It will optionally adjust the page padding to hide the
  white space. You can also configure if you would like to hide the
  toolbar by default.


If your using the contributed admin menu, there is also Admin Menu Hider, which does the same thing, but is in alpha.