实例：锥形渐变彩虹按钮
技术栈：HTML+CSS+JS
效果：
源码：
【HTML】
<!DOCTYPE html>
<html lang="zh-CN"><head><meta charset="UTF-8" /><meta http-equiv="X-UA-Compatible" content="IE=edge" /><meta name="viewport" content="width=device-width, initial-scale=1.0" /><title>锥形渐变彩虹按钮</title><link rel="stylesheet" href="217.css" /></head><body><button class="button" type="button">Light</button><button class="button dark" type="button">Dark</button></body>
</html>
<script src="2
