(function(doc) {
	var addEvent = 'addEventListener',
		type = 'gesturestart',
		qsa = 'querySelectorAll',
		scales = [1, 1],
		meta = qsa in doc ? doc[qsa]('meta[name=viewport]') : [];
	function fix(){
		meta.content = 'width=device-width,minimum-scale=' + scales[0] + ',maximum-scale=' + scales[1];
		doc.removeEventListener(type, fix, true);
	}
	if((meta = meta[meta.length - 1]) && addEvent in doc){
		fix();
		scales = [.25, 1.6];
		doc[addEvent](type, fix, true);
	}
}(document));