<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
*{
padding: 0;
margin: 0;
}
body{
width: 100vw;
height: 100vh;
display: grid;
grid-template: 1fr/1fr;
}
.btn{
width: 200px;
height: 50px;
text-align: center;
line-height: 50px;
color:green;
justify-self: center;
align-self: center;
}
.btn::after{
content: '';
width: 3px;
height: 3px;
display: inline-block;
animation-name: yd;
animation-duration: 1s;
animation-iteration-count: infinite;
}
@keyframes yd {
from{
box-shadow: none;
}
30%{
box-shadow: 3px 0 0 currentColor;
}
60%{
box-shadow: 3px 0 0 currentColor,9px 0 0 currentColor;
}
90%{
box-shadow: 3px 0 0 currentColor,9px 0 0 currentColor,15px 0 0 currentColor;
}
to{
box-shadow: 3px 0 0 currentColor,9px 0 0 currentColor,15px 0 0 currentColor;
}
}
</style>
</head>
<body>
<button class="btn">提交</button>
</body>
</html>