var myWidth = 0, myHeight = 0;
if( typeof( window.innerWidth ) == 'number' ) 
{
	//Non-IE
	myWidth = window.innerWidth;
	myHeight = window.innerHeight;
}
else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) 
{
	//IE 6+ in 'standards compliant mode'
	myWidth = document.documentElement.clientWidth;
	myHeight = document.documentElement.clientHeight;
}
else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) 
{
	//IE 4 compatible
	myWidth = document.body.clientWidth;
	myHeight = document.body.clientHeight;
}

lft = document.getElementById('left');
if(myWidth < 990)
{
	lft.style.width="150px";
}
if(myWidth < 782 )
{
	lft.style.width="100px";
}