(function adaptation() {
    var resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';

    function resize() {
        var html = document.documentElement;
        var wd = html.clientWidth;
        if (wd >= 750) {
            wd = 750
        }
        html.style.fontSize = wd / 7.5 + 'px';
    }
    resize();

    var timer;
    window.addEventListener(resizeEvt, function () {
        timer && clearTimeout(timer);
        timer = setTimeout(resize, 300)
    });
    document.addEventListener('DOMContentLoaded', resize);
})()