.a1 {
      width: 200px;
      height: 60px;
      text-align: center;
      line-height: 60px;
      color: #fff;
      font-size: 18px;
      text-decoration: none;
      font-family: sans-serif;
      box-sizing: border-box;
      background: linear-gradient(90deg, green, orange, green);
      background-size: 400%;
      border-radius: 30px;
      z-index: 1;
      animation: animate 16s linear infinite;
    }

    @keyframes animate {
      0% {
        background-position: 0%;
      }
      100% {
        background-position: 400%;
      }
    }

    .a1:before {
      content: "";
      position: absolute;
      top: -5px;
      left: -5px;
      right: -5px;
      bottom: -5px;
      z-index: -1;
      background: linear-gradient(45deg, #f15523, #ef3224, #7c3697);
      background-size: 400%;
      border-radius: 40px;
      opacity: 0;
      transition: 0.5%;
      animation: animate 16s linear infinite;
    }