.cover{
    background: rgba(0,0,0,.6);
    z-index: 1001;
    position: fixed;
    top:0;
    right: 0;
    bottom: 0;
    left: 0;
    background-color: rgba(0,0,0,.8);
    background-repeat:no-repeat;
    background-position: center 10px;
    background-size: 92% auto;
}
.cover.ios{background-image:url('/images/ios.png');}
.cover.android{background-image:url('/images/android.png');}