.login-box {
    position: absolute;
    top: 40%;
    left: 50%;
    width: 400px;
    padding: 40px;
    transform: translate(-50%, -50%);
    background: rgba(231, 231, 231, 0.5);
    box-sizing: border-box;
    box-shadow: 0 15px 25px rgba(0,0,0,.6);
    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: black;
    margin-bottom: 30px;
    border: none;
    border-bottom: 1px solid black;
    outline: none;
    background: transparent;
  }
  .login-box .user-box label {
    position: absolute;
    top:0;
    left: 0;
    padding: 10px 0;
    font-size: 16px;
    color: black;
    pointer-events: none;
    transition: .5s;
  }
  
  .login-box .user-box input:focus ~ label,
  .login-box .user-box input:valid ~ label {
    top: -20px;
    left: 0;
    color: black;
    font-size: 12px;
  }
  
  .login-box form a {
    position: relative;
    display: inline-block;
    padding: 10px 20px;
    color: black;
    font-size: 16px;
    text-decoration: none;
    text-transform: uppercase;
    overflow: hidden;
    transition: .5s;
    margin-top: 40px;
    letter-spacing: 4px
  }
  
button {
    padding: 15px 25px;
    border: unset;
    border-radius: 15px;
    color: #212121;
    z-index: 1;
    background: #cfcfcf;
    position: relative;
    font-weight: 1000;
    font-size: 17px;
    -webkit-box-shadow: 4px 8px 19px -3px rgba(0,0,0,0.27);
    box-shadow: 4px 8px 19px -3px rgba(0,0,0,0.27);
    transition: all 250ms;
    overflow: hidden;
   }
   
   button::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 0;
    border-radius: 15px;
    background-color: #212121;
    z-index: -1;
    -webkit-box-shadow: 4px 8px 19px -3px rgba(0,0,0,0.27);
    box-shadow: 4px 8px 19px -3px rgba(0,0,0,0.27);
    transition: all 250ms
   }
   
   button:hover {
    color: #e8e8e8;
   }
   
   button:hover::before {
    width: 100%;
   }