jQuery mobile 中div圆角弹出层

HTML:

   <div id="div_layer" class="div_layer">
        已经是最后一个题目
    </div>

CSS:

 .div_layer {
            left: 0;
            right: 0;
            position: fixed;
            z-index: 1001;
            margin: auto;
            bottom: 100px;
            display: none;
            color: white;
            background-color: black;
            -moz-border-radius: 10px;
            -webkit-border-radius: 10px;
            border-radius: 10px;
            width: 180px;
            height: 22px;
            font-size: 12px;
            font-family: 'Microsoft YaHei';
            text-align: center;
            font: 100;
            text-shadow: none;
            padding-top: 5px;
        }

JS

  $('#div_layer').show();
                    setTimeout(function () {
                        $("#div_layer").fadeOut("slow");
                    }, 1500);