function addLoadEvent(func) {
        var oldonload = window.onload;
        if (typeof window.onload != 'function') {
                window.onload = func;
        }
        else {
                window.onload = function() {
                        oldonload();
                        func();
                }
        }
}
function bnDisplay(){
	var window_width = document.body.clientWidth;
	//alert (window_width);
	if (window_width >= 1390) {
		var bl_width = Math.round((window_width/4)*.95 - 6);
		//alert (bl_width);
		document.getElementById('bn_1').style.width = bl_width + "px";
		document.getElementById('bn_2').style.width = bl_width + "px";
		document.getElementById('bn_3').style.width = bl_width + "px";
		
		document.getElementById('bn_4').style.display = "block";
		document.getElementById('bn_4').style.width = bl_width + "px";
	}else {
		document.getElementById('bn_1').style.width = "33%";
		document.getElementById('bn_2').style.width = "33%";
		document.getElementById('bn_3').style.width = "33%";
		
		document.getElementById('bn_4').style.display = "none";
	}

}

addLoadEvent(bnDisplay);
window.onresize=bnDisplay;