頁面增長灰色半透明背景，適用於彈出框。

<div class="newConfirmLayer"></div>

.newConfirmLayer{
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    z-index: 1000;
    background: #333;
    -moz-opacity: 0.3;
    opacity: .30;
    filter: alpha(opacity=30);/* 只支持IE六、七、八、9 */
    display:none;
}