form a{
    background: linear-gradient(#434343,#000000);
    /*background: linear-gradient(blue,#fff);
    background: linear-gradient(#6610f2,#6c757d);*/
    border-radius: 5px;
    position: relative;
    display: inline-block;
    padding: 10px 20px;
    color: #ff0043;
    font-size: 16px;
    text-decoration: none;
    text-transform: uppercase;
    overflow: hidden;
    transition: .5s;
    margin-top: 40px;
    letter-spacing: 4px;
  }
  form a:hover {
    cursor: pointer !important;
    background: #ff0043;
    color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 5px #ff0043,
    0 0 25px #ff0043,
    0 0 50px #ff0043,
    0 0 100px #ff0043;
  }
  form a span{
    position: absolute;
    display: block;
  }
  a span:nth-child(1){
    top: 0;
    left: -100%;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg,transparent,#ff0043);
    animation: btn-anim1 1s linear infinite;
  }
  @keyframes btn-anim1{
    0%{
      left: -100%;
    }
    50%,100%{
      left: 100%;
    }
  }
  a span:nth-child(2){
    top: -100%;
    right: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(180deg,transparent,#ff0043);
    animation: btn-anim1 1s linear infinite;
    animation-delay: .25s;
  }
    @keyframes btn-anim2{
    0%{
      top: -100%;
    }
    50%,100%{
      top: 100%;
    }
  }
  a span:nth-child(3){
    bottom: 0;
    right: -100%;
    width: 100%;
    height: 4px;
    background: linear-gradient(270deg,transparent,#ff0043);
    animation: btn-anim3 1s linear infinite;
    animation-delay: .5s;
  }
    @keyframes btn-anim3{
    0%{
      right: -100%;
    }
    50%,100%{
      right: 100%;
    }
  }
    a span:nth-child(4){
    bottom: -100%;
    left: 0;
    width: 4px;
    height: 100%;
    background: linear-gradient(360deg,transparent,#ff0043);
    animation: btn-anim4 1s linear infinite;
    animation-delay: .75s;
  }
    @keyframes btn-anim4{
    0%{
      bottom: -100%;
    }
    50%,100%{
      bottom: 100%;
    }
  }