CSS字体颜色滚动渐变动画

显示效果如上图所示，此外还包含颜色滚动效果。代码如下：

HTML：

<p class="colorful ovh">
        <a href="/go.html?url=https://weidian.com/?userid=1302830717&code=081hokh32X0I3M0FH6i32J14h32hokh1" class="btn" target="_blank">签名版</a>
        <a href="/go.html?url=https://item.jd.com/12262251.html" class="btn" target="_blank">京东自营</a>
        <a href="/go.html?url=https://product.dangdang.com/25206611.html" class="btn" target="_blank">当当自营</a>
        <a href="/go.html?url=https://www.amazon.cn/dp/B0788XRYGF/" class="btn" target="_blank">亚马逊</a>
        <a href="/go.html?url=https://www.epubit.com.cn/book/details/4767" class="btn" target="_blank">异步社区</a>
</p><p cla