ul li{
position:relative;}

ul li a p{
    height: 50px;
    position: absolute;
    color: #ffffff;
right:0;
    bottom: 20px;
    width: 500px;
    background: rgba(0,0,0,0.5);
    /* opacity: 0.5; */
    line-height: 50px;
    text-align: center;
    font-size:16px;}