代码示例:(标识:css3_gradient-radial_shape)
<!DOCTYPE html>
<html>
<head>
<style>
#grad1 {
  height: 150px;
  width: 200px;
  background-color: red; /* 针对不支持渐变的浏览器 */
  background-image: radial-gradient(red, yellow, green);
}

#grad2 {
  height: 150px;
  width: 200px;
  background-color: red; /* 针对不支持渐变的浏览器 */
  background-image: radial-gradient(circle, red, yellow, green);
}
</style>
</head>
<body>

<h1>径向渐变 - 形状</h1>

<h2>椭圆(默认):</h2>
<div id="grad1"></div>

<h2>圆:</h2>
<div id="grad2"></div>

</body>
</html>
运行结果: