css 遮罩层简单应用

html

测试
    

css

 #bg {
	display:none;
	position:absolute;
	top:0%;
	left:0%;
	width:100%;
	height:100%;
	background-color:black;
	z-index:1001;
	-moz-opacity:0.7;
	opacity:.70;
	filter:alpha(opacity=70);
}
#show {
	display:none;
	position:absolute;
	top:25%;
	left:22%;
	width:53%;
	height:49%;
	padding:8px;
	border:8px solid #E8E9F7;
	background-color:white;
	z-index:1002;
	overflow:auto;
}

js

function showdiv() {
    document.getElementById("bg").style.display = "block";
    document.getElementById("show").style.display = "block";
}

function hidediv() {
    document.getElementById("bg").style.display = 'none';
    document.getElementById("show").style.display = 'none';
}