//屏幕尺寸
(function(doc, win) {
	var docel = doc.documentelement,
		isios = navigator.useragent.match(/iphone|ipod|ipad/gi),
		dpr = isios ? math.min(win.devicepixelratio, 3) : 1,
		dpr = window.top === window.self ? dpr : 1, //被iframe引用时，禁止缩放
		dpr = 1, // 首页引用iframe，强制为1
		scale = 1 / dpr,
		resizeevt = 'orientationchange' in window ? 'orientationchange' : 'resize';
	docel.dataset.dpr = win.devicepixelratio;
	if (navigator.useragent.match(/iphone/gi) && screen.width == 375 && win.devicepixelratio == 2) {
		docel.classlist.add('iphone6')
	}
	if (navigator.useragent.match(/iphone/gi) && screen.width == 414 && win.devicepixelratio == 3) {
		docel.classlist.add('iphone6p')
	}
	var metael = doc.createelement('meta');
	metael.name = 'viewport';
	metael.content = 'initial-scale=' + scale + ',maximum-scale=' + scale + ', minimum-scale=' + scale;
	docel.firstelementchild.appendchild(metael);
	var recalc = function() {
		var width = docel.clientwidth;
		if (width / dpr > 750) {
			width = 750 * dpr;
		}
		docel.style.fontsize = 100 * (width / 750) + 'px';
	};
	recalc()
	if (!doc.addeventlistener) return;
	win.addeventlistener(resizeevt, recalc, false);
})(document, window);