var x,y;
 if (self.innerHeight) // all except Explorer
 {
   x = self.innerWidth;
   y = self.innerHeight;
 }
 else if (document.documentElement && document.documentElement.clientHeight)
   // Explorer 6 Strict Mode
 {
   x = document.documentElement.clientWidth;
   y = document.documentElement.clientHeight;
 }
 else if (document.body) // other Explorers
 {
   x = document.body.clientWidth;
   y = document.body.clientHeight;
 }

 if ( x > 800 ) {
   document.writeln
   ('<!'+'-- --'+'>')
 } else {
   document.writeln('<link rel="stylesheet" href="/css/800.css" media="all" type="text/css" />')
 }