要使用CSS在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 {
border: 2px solid black;
width: 300px;
height: 100px;
position: absolute;
left: 0;
animation: myanim 5s infinite;
}
@keyframes myanim {
30% {
left: 200px;
}
}
</style>
</head>
<body>
<div>This is demo text</div>
</body>
</html>