css动画 圆形扩散

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS Circle Diffusion Animation</title>
    <style>
        .circle {
            width: 100px;
            height: 100px;
            background-color: red;
            border-radius: 50%;
            animation: diffusion 2s linear infinite;
        }

        @keyframes diffusion {
            0% {
                transform: scale(1);
                opacity: 1;
            }
            100% {
                transform: scale(2);
                opacity: 0;
            }
        }
    </style>
</head>
<body>
    <div class="circle"></div>
</body>
</html>