要使用CSS在z-index属性上实现动画，您可以尝试运行以下代码-
<!DOCTYPE html>
<html>
<head>
<style>
div {
position: absolute;
}
#box div {
background-color: orange;
border: 2px solid yellow;
width: 100px;
height: 100px;
opacity: 0.3;
}
div#demo {
opacity: 1;
background-color: coral;
z-index: 1;
animation: myanim 3s;
}
@keyframes myanim {
30% {
z-index: 3;
}
}
</style>
</head>
<body>
<h1>CSS z-index property</h1>
<div id = "box">
<div id = "demo"></div>
<div style = "top:20px;left:20px;z-index:1;">One</div>
<div style = "top:40px;left:40px;z-index:2;">Two</div>
<div style = "top:60px;left:60px;z-index:3;">Three</div>
<div style = "top:80px;left:80px;z-index:4;">Four</div>
<div style = "top:100px;left:40px;z-index:5;">Five</div>
<div style = "top:120px;left:60px;z-index:6;">Six</div>
<div style = "top:140px;left:80px;z-index:7;">Seven</div>
</div>
</body>
</html>