CSS实现渐变色边框（Gradient borders）

单层元素、background-clip、background-origin、background-image
分别设置 background-clip、background-origin、background-image 这三个属性，每个属性设置两组值，第一组用于设置border内的单色背景，第二组用于设置border上的渐变色。

HTML:

<div class="border-box"><div class="content">Lorem ipsum dolor, sit amet consectetur adipisicing elit. Iste ratione necessitatibus numquam sunt nihil quossaepe sit facere. Alias accusamus voluptate accusantium facere fugiat animi temporibus adipisci! Corporis,accusamus tempora.</div>
</div>

CSS:

.border-box {border: 4px solid transparent;border-radius: 16px;background-clip: padding-box, border-box;background-origin: padding-box, border-box;background-image: linear-gradient(to right, #222, #222), linear-gradient(90deg, #8F41E9, #578AEF);
}