/**
 * handles layouting of content frame depending on window width. 
 */
function doLayout() {	
	var wrapper = document.getElementById("wrapper");
	if(wrapper) {	
		var winInnerWidth = 0;
		var winInnerOffset = 0;
		// determine (browser dependant) window's inner width
		if(window.innerWidth) {
			winInnerWidth =  window.innerWidth;			
		} else if ( document.body.clientWidth){
			winInnerWidth =  document.body.clientWidth;
		}
		if(winInnerWidth>=1024) {
			winInnerOffset = (Math.floor((winInnerWidth - 1000)/2)-20);				
		}	else {
			winInnerOffset =  0;						
		}
		if (winInnerOffset<0) {winInnerOffset=0;};
		wrapper.style.marginLeft = winInnerOffset+"px";			
	}
}
// triggers layouting
window.onresize=doLayout;