<!DOCTYPE html>
<html>
<head>
<style>
#grad1 {
height: 200px;
background-image: linear-gradient(red, yellow, blue);
}
</style>
</head>
<body>
<h1>线性渐变 - 从上到下</h1>
<p>这个线性渐变从上到下。它从红色过渡到黄色，再到蓝色：</p>
<div id="grad1"></div>
</body>
</html>