安卓调整系统字体导致rem布局错乱

fix.js

    function calcREM() {
        var docEl = document.documentElement;
        var width = docEl.getBoundingClientRect().width;
        var rem = width / 7.5;
        rem = parseFloat(rem.toFixed(3));
        docEl.style.fontSize = rem + 'px';
        // 修正系统字体调整造成的布局问题
        var realitySize = parseFloat(window.getComputedStyle(document.documentElement).fontSize);
        if (rem !== realitySize) {
            rem = rem * rem / realitySize;
            docEl.style.fontSize = rem + 'px';
        }
        window.REM = rem;
    }