body {
      font-family: sans-serif;
      text-align: center;
      margin: 0;
      background-color: #ff9966;
    }
    #gallery {
      max-width: 90vw;
      margin: 2em auto;
      position: relative;
    }
    #gallery img {
      max-width: 100vw;
      max-height: 90vh;
      width: auto;
      height: auto;
      object-fit: contain;
    }
    .hidden {
      display: none;
    }
    #startImage {
      cursor: pointer;
    }
    .nav-button {
      position: absolute;
      top: 50%;
      transform: translateY(-50%);
      font-size: 2em;
      background: rgba(0,0,0,0.5);
      color: white;
      border: none;
      cursor: pointer;
      padding: 0.5em;
    }
    #prevBtn {
      left: 10px;
    }
    #nextBtn {
      right: 10px;
    }