關於移動端的佈局

第一種，flexible佈局：

;(function(designWidth, maxWidth) {
    var doc = document,
        win = window,
        docEl = doc.documentElement,
        remStyle = document.createElement("style"),
        tid;

    function refreshRem() {
        var width = docEl.getBoundingClientRect().width;
        maxWidth = maxWidth || 540;
        width > maxWidth && (width = maxWidth);
        var rem = width * 100 / designWidth;
        remStyle.innerHTML = 'html{font-size:' + rem + 'px;}';
    }

    if (docEl.firstElementChild) {
        docEl.firstElementChild.appendChild(remStyle);
    } else {
        var wrap = doc.createElement("div");
        wrap.appendChild(remStyle);
        doc.write(wrap.innerHTML);
        wrap = null;
    }
    //要等 wiewport 設置好後才能執行 refreshRem，否則 refreshRem 會執行2次；
    refreshRem();

    win.addEventListener("resize", function() {
        clearTimeout(tid); //防止執行兩次
        tid = setTimeout(refreshRem, 300);
    }, false);

    win.addEventListener("pageshow", function(e) {
        if (e.persisted) { // 瀏覽器後退的時候從新計算
            clearTimeout(tid);
            tid = setTimeout(refreshRem, 300);
        }
    }, false);

    if (doc.readyState === "complete") {
        doc.body.style.fontSize = "16px";
    } else {
        doc.addEventListener("DOMContentLoaded", function(e) {
            doc.body.style.fontSize = "16px";
        }, false);
    }
})(750, 750);

rem=px/50;

第二種，media css實現：

html {
    font-size:20px
}
@media only screen and (min-width:400px) {
    html {
        font-size:21.33333333px!important
    }
}
@media only screen and (min-width:414px) {
    html {
        font-size:22.08px!important
    }
}
@media only screen and (min-width:480px) {
    html {
        font-size:25.6px!important
    }
}

rem=px/20