CSS彩虹跑马灯边框效果

<view class="gradient-border">跑马灯效果</view>

.gradient-border {
  --border-width: 3px;
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  width: 300px;
  height: 200px;
  font-family: Lato, sans-serif;
  font-size: 2.5rem;
  text-transform: uppercase;
  color: white;
  background: #222;
  border-radius: var(--border-width);
}

.gradient-border::after {
  position: absolute;
  content: "";
  top: calc(-1 * var(--border-width));
  left: calc(-1 * var(--border-width));
  z-index: -1;
  width: calc(100% + var(--border-width) * 2);
  height: calc(100% + var(--border-width) * 2);
  background: linear-gradient(60deg, #5f86f2, #a65ff2, #f25fd0, #f25f61, #f2cb5f, #abf25f, #5ff281, #5ff2f0);
  background-size: 300% 300%;
  background-position: 0 50%;
  border-radius: calc(2 * var(--border-width));
  animation: moveGradient 4s alternate infinite;
}

@keyframes moveGradient {
  50% {
    background-position: 100% 50%;
  }
}