网站后台—>外观—>小工具—>自定义HTML，然后添加到合适位置集合即可。

代码：

<!--跑马灯公告-->
<style>
  #nr{font-size:20px; margin: 0; background: -webkit-linear-gradient(left, #ffffff, #ff0000 6.25%, #ff7d00 12.5%, #ffff00 18.75%, #00ff00 25%, #00ffff 31.25%, #0000ff 37.5%, #ff00ff 43.75%, #ffff00 50%, #ff0000 56.25%, #ff7d00 62.5%, #ffff00 68.75%, #00ff00 75%, #00ffff 81.25%, #0000ff 87.5%, #ff00ff 93.75%, #ffff00 100%); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-size: 200% 100%; animation: masked-animation 2s infinite linear;} @keyframes masked-animation{0%{background-position: 0 0;} 100%{background-position: -100%, 0;} }
</style>
    <div style="background-color:#333;border-radius:25px;box-shadow:0px 0px 5px #f200ff;padding:5px;margin-bottom:0px;">
        <marquee>
        <b id="nr">欢迎来到好代码 - 网络IT科技魅力博客。</b> </marquee>
    </div>