n6 = (navigator.userAgent.indexOf("Gecko")!=-1);
ns4 = (document.layers)? true:false;
ie4 = (document.all)? true:false;
ng5 = (document.getElementById) ? true:false

var screen_w=0;
var screen_h=0;

function pagina() {
	if(ns4) {
		screen_w = window.innerWidth;
		screen_h = window.innerHeight;
	} else { 
		if(n6) {
			screen_w = window.innerWidth;
			screen_h = window.innerHeight;
		} else {
			screen_w = document.body.clientWidth;
			screen_h = document.body.clientHeight;
		}
	}
	if (n6 || ns4 ) {
		document.image_alt.height = (screen_h-60)-245;
	} else {
		window.document.image_alt.height = (screen_h-60)-245;
	}
}