直接上代码：
<!doctype html>
<html>
<head>
<meta charset="utf-8" />
<title>阴阳鱼</title>
<style>
body { background: #F0DFAD; }
.yin-yang { position: fixed; top: 50%; left: 50%; margin: -5rem 0 0 -5rem; height: 10rem; width: 10rem; border-radius: 50%; background: -webkit-linear-gradient(top, #fff 0%, #fff 50%, #000 50%, #000 100%); background: linear-gradient(to bottom, #fff 0%, #fff 50%, #000 50%, #000 100%); box-shadow: 0 0 1rem rgba(0, 0, 0, 0.4); -webkit-animation: rotate 10s linear infinite; animation: rotate 10s linear infinite; } @-webkit-keyframes rotate {
0% { -webkit-transform: rotate(0); transform: rotate(0); }
100% { -webkit-transform: rotate(360deg); transform: rotate(360deg); }
} @keyframes rotate {
0% { -webkit-transform: rotate(0); transform: rotate(0); }
100% { -webkit-transform: rotate(360deg); transform: rotate(360deg); }
} .yin-yang:before,
.yin-yang:after { content: ''; box-sizing: border-box; position: absolute; top: 50%; -webkit-transform: translateY(-50%); transform: translateY(-50%); height: 50%; width: 50%; border-radius: 50%; }
.yin-yang:before { left: 0; background: #FFF; border: 2rem solid #000; }
.yin-yang:after { right: 0; background: #000; border: 2rem solid #fff; }
</style>
</head>
<body>
<div class="yin-yang"></div>
</body>
</html>