function setrem() {
    var html = document.documentelement
    var ww = html.clientwidth
    if (ww <= 1024 && ww > 750) {
        var whdef = 100 / 750
        var rem = 750 * whdef
    } else if (ww <= 750) {
        var whdef = 100 / 750
        var rem = ww * whdef
    } else {
        ww = math.min(ww, 1440)
        var whdef = 100 / 1440
        var rem = ww * whdef
    }
    document.documentelement.style.fontsize = rem + 'px'
}
setrem();
window.onresize = function(){
    setrem()
}