css 父层 透明 子层不透明Alpha

<div class="user2-register-bg">
            <div class="user2-register-con">
                1111
            </div>
        </div>

.user2-register-bg{padding: 10px;padding: 10px;background:rgba(0,0,0,0.3)!important;background:#000;filter:Alpha(opacity=30); margin-top: 30px;}
.user2-register-con{height:500px; background:#fff;  position:relative; }