要在CSS中的margin-left属性上实现动画，您可以尝试运行以下代码
<!DOCTYPE html>
<html>
<head>
<style>
div {
background-color: gray;
animation: myanim 3s infinite;
color: white;
}
@keyframes myanim {
30% {
margin-left: 20px;
}
}
</style>
</head>
<body>
<h2>Heading One</h2>
<div>
This is demo text.
</div>
</body>
</html>