(function () {	var docEl = document.documentElement;	var resize = 'orientationchange' in window ? 'orientationchange' : 'resize';	var setRem = function () {		var screenWidth = docEl.clientWidth || window.screen.width || 360;		// 1080 PSD宽度(可变的)		docEl.style.fontSize = (100 * screenWidth / 1080) + 'px';	}; 	window.addEventListener('resize', setRem, false);	setRem();})(); // 用法 psd量出来的像素距离 除以100  比如psd: 100px 转换后 1rem;