function wResize() {
	var oWidth = document.getElementById('main_img').width;
	var nWidth = document.documentElement.clientWidth;
	var oHeight = document.getElementById('main_img').height;
	var nHeight = 0;
	
	nHeight = (nWidth / oWidth) * oHeight;
	
	document.getElementById('main_img').width = nWidth;
	document.getElementById('main_img').height = nHeight;
}