以rem为单位移动端页面开发

头部需要添加meta标签

<meta name="viewport" content="width=device-width, initial-scale= 1, maximum-scale=1">

JS设置HTML的font-size

(function(doc, win) {
        var docEl = doc.documentElement,
                resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
                recalc = function() {
                    var clientWidth = docEl.clientWidth > 640 ? 640 : docEl.clientWidth;
                    if (!clientWidth) return;
                    docEl.style.fontSize = 20 * (clientWidth / 320) + 'px';
                };

        if (!doc.addEventListener) return;
        win.addEventListener(resizeEvt, recalc, false);
        doc.addEventListener('DOMContentLoaded', recalc, false);
    })(document, window);