移动端rem问题

rem自适应设置：设计稿宽度750px(iphone6/7/8)

设置：1rem = 100px，font-size: 0.16rem;  //font-size: 16px;

(function (doc, win) {
    var docEl = doc.documentElement,
        resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
        recalc = function () {
            var clientWidth = docEl.clientWidth;
            if (!clientWidth) return;
            // fontSize / 100 = clientWidth / 750;
            docEl.style.fontSize = (clientWidth / 7.50) + 'px';
        };

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