效果例图：（因gif图片太大，而csdn只能上传小于5m图片，所以无法上传）
1、首先上传html代码：
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<link rel="stylesheet" href="./3.css">
<title>Document</title>
</head>
<body>
<div class ="text">
CSS 渐变酷炫背景动画效果
</div>
</body>
</html>2、上传核心CSS3代码：
body{
height: 100vh;
width: 100vw;
margin: 0;
padding: 0;
font-family: 'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
background-size: 400%;
background-image: linear-gradient(90deg,#2c3e50,#27ae60,#b9aa29,#2980b9,#e74c3c,#8e44ad);
animation: bganimation 15s infinite;
}
.text{
color: white;
text-align: center;
text-transform: uppercase;
padding: 30vh;
font-size: 22px;
}
@keyframes bganimation{
0%{
background-position: 0% 50%;
}
50%{
background-position: 100% 50%;
}
100%{
background-position: 0% 50%;
}
}
