html {
  scroll-behavior: smooth;
}

#footer {
  background-image: linear-gradient(
    rgba(245, 245, 245, 0.9), 
    rgba(245, 245, 245, 0.9)
  ),url('/images/haus.jpg');
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

.modal-window {
    position: fixed;
    background-color: rgba(255, 255, 255, 0.25);
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 999;
    opacity: 0;
    pointer-events: none;
    transition: all 0.3s;
  }
  .modal-window:target {
    opacity: 1;
    pointer-events: auto;
  }
  .modal-window > div {
    width: 70%;
    height: 80%;
    position: absolute;
    top: 50%;
    left: 50%;
    -webkit-transform: translate(-50%, -50%);
            transform: translate(-50%, -50%);
    padding: 2em;
    background: #eee;
    color: #333333;
    overflow: scroll;
    padding: 3em;
    margin: 5em;
  }
  .modal-window header {
    font-weight: bold;
  }
  .modal-window h1 {
    font-size: 150%;
    margin: 0 0 15px;
    color: #333333;
  }
  
  .modal-close {
    color: #999;
    border: none;
    line-height: 50px;
    font-size: 90%;
    position: absolute;
    right: 0;
    text-align: center;
    top: 0;
    width: 70px;
    text-decoration: none;
  }
  .modal-close:hover {
    color: #000;
  }