console
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>小米商品案例</title>
<style>
*{
margin: 0;
padding: 0
}
.father{
position: relative;
width: 200px;
height: 200px;
border: 1px solid ;
}
.son{
position: absolute;
bottom: 0;
left: 0;
width: 100%;
height: 0;
background-color: red;
opacity: 0；
transition: all 0.5s linear;
-webkit-transition: all 0.5s linear
}
.father:hover .son{
opacity: 1;
height: 50px;
}
</style>
</head>
<body>
<div class="father">
<div class="son">
</div>
</div>
</body>
</html>