(jqm 1.3) How to change the width of the panel?

(jqm 1.3) How to change the width of the panel?

Has anyone tried the Panel feature in 1.3? I'd like to make the panel wider: say to 1/3 of the screen width. I tried overriding the .ui-panel width style, but the slideout delta remains unchanged (ie. the content div slid by the same amount). I do see that the panel width itself has been altered as per my style settings, because the shadow effect is gone.

I notice with interest something similar:

But it also uses the width style. Am I missing something?

Here's my simple attempt at changing the panel width:
  2.         .ui-panel 
  3.         {
  4.             width: 800px;
  5.         }