.this {
  .fixed {
    position: fixed;
  }
  .fixedBox {
    position: fixed;
    width: 100%;
    maxWidth: 450;
    height: 100%;
    top: 0;
    background: rgba(0, 0, 0, .6);
    zIndex: 5;
  }

  @keyframes showModel {
    from {
      opacity: 0;
    }
    to {
      opacity: 1;
    }
  }
  animation: showModel 0.3s ease-in-out forwards;
}