index.css

body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: #000;
}
/* 设置按钮宽高，居中，底色 */
.base {
  position: relative;
  display: inline-block;
  width: 200px;
  height: 60px;
  background-color: skyblue;
  color: #fff;
  line-height: 60px;
  text-align: center;
  &:hover {
    animation: animate 5s linear infinite;
    &:before {
      filter: blur(20px);
      opacity: 1;
    }
  }
  &:before {
    content: '';
    position: absolute;
    left: -5px;
    top: -5px;
    right: -5px;
    bottom: -5px;
    z-index: -1;
    background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
    background-size: 400%;
    border-radius: 10px;
    /* 默认不显示光影 */
    opacity: 0;
    transition: all 1s;
  }
}
.linear {
  text-decoration: none;
  background: linear-gradient(90deg, #03a9f4, #f441a5, #ffeb3b, #03a9f4);
  /* 设置背景图的大小，起始处 */
  background-size: 400%;
  border-radius: 10px;
}
@keyframes animate {
  0% {
    background-position: 0 0;
  }
  100% {
    background-position: 400% 0;
  }
}