/* Reset & Base */
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #121212;
    color: #e0e0e0;
    line-height: 1.6;
  }

  /* Section Container */
  .book-timeline-section {
    max-width: 1200px;
    margin: 50px auto;
    padding: 0 20px;
  }

  .timeline-title {
    text-align: center;
    margin-bottom: 40px;
    font-size: 1.8rem;
    font-weight: bold;
    color: #f5f5f5;
  }

  /* Timeline Wrapper */
  .timeline {
    position: relative;
    display: flex;
    flex-direction: column;
    gap: 70px;
  }

  /* Timeline Line */
  .timeline::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 4px;
    height: 100%;
    background: #555; /* default neutral line color */
    border-radius: 2px;
  }

  /* Timeline Item */
  .timeline-item {
    position: relative;
    display: flex;
    align-items: center;
    width: 100%;
    flex-direction: row;
    gap: 25px;
    opacity: 1; /* fully visible by default */
  }

  .timeline-item:nth-child(even) {
    flex-direction: row-reverse;
  }

  /* Book Image */
  .book-image {
    flex: 0 0 140px;
    width: 140px;
    overflow: hidden;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }

  .book-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
  }

  .book-image:hover {
    transform: scale(1.06);
  }

  /* Book Content */
  .book-content {
    max-width: 450px;
    padding: 20px;
    border-radius: 12px;
    transition: transform 0.3s ease, background 0.3s ease;
  }

  .book-content h3 {
    margin-bottom: 10px;
    font-size: 1.2rem;
  }

  .book-content p {
    font-size: 0.95rem;
  }

  /* Responsive */
  @media (max-width: 768px) {
    .timeline::before {
      left: 20px;
    }
    .timeline-item, .timeline-item:nth-child(even) {
      flex-direction: row !important;
      margin-left: 20px;
      gap: 20px;
    }
    .book-content {
      padding: 18px;
    }
  }

  /* --------------------
     Individual Book Styles
     -------------------- */

  /* Book 1 Colors */
  .book1 .book-content {
    background: #2e1e20;
    color: #ffe0e7;
    box-shadow: 0 0 25px rgba(255, 22, 34, 0.4);
  }
  .book1 .book-content h3 {
    color: #fd5866;
  }
  .book1 .book-image {
    box-shadow: 0 0 25px rgba(255, 120, 131, 0.4);
  }
  .book1 .book-image:hover {
    box-shadow: 0 0 35px rgba(255, 101, 17, 0.813);
  }

  /* Book 2 Colors */
  .book2 .book-content {
    background: #1e2a2e;
    color: #c8fcff;
    box-shadow: 0 0 25px rgba(0, 229, 255, 0.4);
  }
  .book2 .book-content h3 {
    color: #00e1ff;
  }
  .book2 .book-image {
    box-shadow: 0 0 25px rgba(0, 162, 255, 0.4);
  }
  .book2 .book-image:hover {
    box-shadow: 0 0 35px rgba(0, 225, 255, 0.887);
  }

  /* Book 3 Colors */
  .book3 .book-content {
    background: #202e1e;
    color: #c9ffc8;
    box-shadow: 0 0 25px rgba(120, 255, 125, 0.4);
  }
  .book3 .book-content h3 {
    color: #91ff78;
  }
  .book3 .book-image {
    box-shadow: 0 0 25px rgba(147, 255, 120, 0.4);
  }
  .book3 .book-image:hover {
    box-shadow: 0 0 35px rgba(193, 75, 251, 0.749);
  }