without sidebars

Glad to hear you like the theme.

As for your question, you could add in some PHP and CSS to check if there is a sidebar coming in. If there isn't any sidebar, include some embedded CSS. I just did a small firebug test and got this.

<style type="text/css"> 
  #content {
    width: 695px;
  }
</style>

This code would need to be placed somewhere in the head tags after the $style tag sections.

As for the checking code, it'll be some php code that is wrapped in an if statement..

something like

if(!$right && ! $left) {
  // print code here.
}

http://www.w3schools.com/php/php_if_else.asp

That should be everything you need. Hope that helps.

looks like this can be safely closed.