(function (window, document) {
    var sizeUI = 750; // 定义设计图尺寸
    var remBase = 75; // 定义基准值
    var docEl = document.documentElement;
    var bodyEl = document.querySelector("body");

    setRemUnit();

    window.addEventListener("resize", setRemUnit);
    window.addEventListener("pageshow", function (e) {
        if (e.persisted) setRemUnit();
    });

    function setRemUnit() {
        var docFontSize = (docEl.clientWidth / sizeUI) * remBase;
        docEl.style.fontSize = docFontSize + "px";
        bodyEl.style.fontSize = 16 / docFontSize + "rem";
        handleRemAdapt();
    }

    function handleRemAdapt() {
        var currentFontSize = parseInt(docEl.style.fontSize);
        var temp = currentFontSize;
        for (var i = 0; i < 100; i++) {
            var realFontSize = parseInt(window.getComputedStyle(docEl).fontSize);
            var differ = realFontSize - currentFontSize;
            if (Math.abs(differ) >= 1) {
                if (differ > 0) {
                    temp--;
                } else {
                    temp++;
                }
                docEl.style.fontSize = temp + "px";
            } else {
                break;
            }
        }
    }
})(window, document);