vape_shop/public/assets/index/js/flexible.js

!(function (win, doc) {
    let docEl = doc.documentElement,
        resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
        recalc = function () {
            const clientWidth = docEl.clientWidth;
            if (!clientWidth) return;
            const number = 100 * (clientWidth / 750)

            if (clientWidth >= 750) {
                docEl.style.fontSize = 100 + 'px';
            } else {
                docEl.style.fontSize = number + 'px';
            }
        };
    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false);
    doc.addEventListener('DOMContentLoaded', recalc, false);

}(window, document));