html,body{
    height:100%;
    padding:0;
    margin:0;
  }
  *{
    box-sizing:border-box;
  }
  
  .main__container{
    
    width:100%;
    height:100%;
    background-color:#444;
    
    display:flex;
    justify-content:center;
    align-items:center;
    
  }
  
  #btn-enter {
    width: 100%;
  }