要使用CSS在max-width属性上实现动画，您可以尝试运行以下代码
<!DOCTYPE html>
<html>
<head>
<style>
div {
overflow: auto;
background-color: blue;
color: white;
border: 1px solid black;
animation: myanim 3s;
}
@keyframes myanim {
30% {
max-width: 250px;
}
}
</style>
</head>
<body>
<h1>Example of max-width</h1>
<div>
<p>This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
This is demo text. This is demo text. This is demo text.
</p>
</div>
</body>
</html>