/**
 * 弹层实现
 */

.dialog {
    width: 400px;
    height: 200px;
	background: #f06;
	background: linear-gradient(45deg, #f06, yellow);
    margin-top: 200px;
}

.dialog:before {
    content: '';
	position: fixed;
	top: 0;
	left: 0;
	right: 0;
	bottom: 0;
	background: rgba(0,0,0,.4);
	z-index: -1;
}