根据juery CSS点击一个标签弹出一个遮罩层的简单示例

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>

    <title></title>

    <script src="JS/JavaScript/jquery-1.7.2.min.js"></script>

    <style type="text/css">

        .Calculator_box-opened {

            width: 100%;

            height: 100%;

            position: fixed;

            top: 0px;

            left: 0px;

            overflow-y: visible;

            display: none;

            background-color: #000;

            opacity: 0.8;

            filter: alpha(Opacity=80, FinishOpacity=50, Style=0, StartX=0, StartY=0, FinishX=100, FinishY=100);

            z-index: 1099;

        }

        .Calculator_box {

            padding: 0px;

            width: 520px;

            margin: 100px auto;

            text-align:center;

            background-color: #FFF;

            position: relative;

        }

    </style>

    <script type="text/javascript">

        $(document).ready(function () {

            var speed = 600;//动画速度

            $("#dj").click(function (event) {//绑定事件处理

                event.stopPropagation();

                $("#Calculator").show(speed);//动画显示

            });

            //单击除空白区域外的空白区域就隐藏

            $(document).click(function () {

                if (!$(event.srcElement).is(".Calculator_box,.Calculator_box *")) {

                    $("#Calculator").hide(speed);

                }

            });

        });

    </script>

</head>

<body>

    <input type="button" value="点击我弹出层吧" id="dj" />

    <div class="Calculator_box-opened" id="Calculator">

        <div class="Calculator_box">

             <span style="color:red; font-size:16px">大家好，我是弹出层哟！</span>

        </div>

    </div>

</body>

</html>
　　简单示例比较容易懂！