示例代码如下
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
.dot {
width: 100px;
height: 100px;
border: 1px solid #2f5594;
border-radius: 50%;
background: #2f5594;
}
</style>
</head>
<body>
<div class="dot"></div>
</body>
</html>