html {
    height: 100%;
  }
  body {
    margin:0;
    padding:0;
    font-family: sans-serif;
    background: linear-gradient(#343f53, #99a6b5);
  }
  
  .login-box {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 400px;
    padding: 40px;
    transform: translate(-50%, -50%);
    background: rgba(0, 0, 0, 0);
    box-sizing: border-box;
    border-radius: 10px;
  }
  
  .login-box h2 {
    margin: 0 0 30px;
    padding: 0;
    color: #fff;
    text-align: center;
  }
  
  .login-box .user-box {
    position: relative;
  }
  
  .login-box .user-box input {
    width: 100%;
    padding: 10px 0;
    font-size: 16px;
    color: #fff;
    margin-bottom: 30px;
    border: none;
    border-bottom: 1px solid #fff;
    outline: none;
    background: transparent;
  }
  .login-box .user-box label {
    position: absolute;
    top:0;
    left: 0;
    padding: 10px 0;
    font-size: 16px;
    color: #fff;
    pointer-events: none;
    transition: .5s;
  }
  
  .login-box .user-box input:focus ~ label,
  .login-box .user-box input:valid ~ label {
    top: -20px;
    left: 0;
    color: #03e9f4;
    font-size: 12px;
  }
  
  .login-box form button {
    position: relative;
    display: inline-block;
    padding: 10px 20px;
    color: #03e9f4;
    font-size: 16px;
    text-transform: uppercase;
    overflow: hidden;
    transition: 0.5s;
    margin-top: 40px;
    letter-spacing: 4px;
    background: transparent;
    border: none;
    cursor: pointer;
  }
  
  .login-box form button:hover {
    background: #03e9f4;
    color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 5px #03e9f4,
      0 0 25px #03e9f4,
      0 0 50px #03e9f4,
      0 0 100px #03e9f4;
  }

.login-box form button span {
  position: absolute;
  display: block;
}
  
.login-box form button span:nth-child(1) {
  top: 0;
  left: -100%;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, transparent, #03e9f4);
  animation: btn-anim1 1s linear infinite;
}

.login-box form button span:nth-child(2) {
  top: -100%;
  right: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(180deg, transparent, #03e9f4);
  animation: btn-anim2 1s linear infinite;
  animation-delay: 0.25s;
}

.login-box form button span:nth-child(3) {
  bottom: 0;
  right: -100%;
  width: 100%;
  height: 2px;
  background: linear-gradient(270deg, transparent, #03e9f4);
  animation: btn-anim3 1s linear infinite;
  animation-delay: 0.5s;
}

.login-box form button span:nth-child(4) {
  bottom: -100%;
  left: 0;
  width: 2px;
  height: 100%;
  background: linear-gradient(360deg, transparent, #03e9f4);
  animation: btn-anim4 1s linear infinite;
  animation-delay: 0.75s;
}
  .back 
{
    width: 100%;
    height: 100%;
    object-fit: cover;
    position: fixed;

}
  
  @keyframes btn-anim1 {
    0% {
      left: -100%;
    }
    50%,100% {
      left: 100%;
    }
  }
  

  
  @keyframes btn-anim2 {
    0% {
      top: -100%;
    }
    50%,100% {
      top: 100%;
    }
  }
  

  
  @keyframes btn-anim3 {
    0% {
      right: -100%;
    }
    50%,100% {
      right: 100%;
    }
  }

  @keyframes btn-anim4 {
    0% {
      bottom: -100%;
    }
    50%,100% {
      bottom: 100%;
    }
  }