技術標籤：css

<div class="tudou">
    <div class="mask">
    <img src="images/tudou.jpg" alt="">
</div>

.tudou { 
    position: relative;
    width: 44px;
    height: 320px;
    margin: 30px auto;
    background-color: pink;
}
.tudou img {
    width: 100%;
    height: 100%;
}
.mask {
    /* 隱藏遮蔽罩 */
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,.3) url(images/arr.png) no-repeat center;
}
/* 當滑鼠經過了土豆這個盒子，就讓裡面的遮蔽罩顯示出來 */
.tudou:hover .mask {
    display: block;
}