window.addEvent('load', function() {
   var tresholdWidth = $('topright').getStyle('left').toInt();
   fixTopGradient(tresholdWidth);

   window.addEvent('resize', function() {
      fixTopGradient(tresholdWidth);
   });
});

var fixTopGradient = function(tresholdWidth)
{
   var windowWidth = window.getSize().x;

   if(windowWidth > tresholdWidth) {
      $('topright').setStyle('width', -tresholdWidth + windowWidth);
      $('top').setStyle('width', windowWidth);
   }
   else {
      $('topright').setStyle('width', 0);
      $('top').setStyle('width', tresholdWidth);
   }
}