<head>
<style>
.mask{
position: absolute;
width: 502px;
height: 252px;
left:300px;
top:350px;
background: white;
z-index: 999;
}
.con {
width: 500px;
height: 500px;
overflow: hidden;
position: absolute;
border-radius: 100%;
border: 1px solid black;
user-se