body {
      font-family: Arial, sans-serif;
      background: #f9f9f9;
      margin: 0;
      padding: 20px;
    }

    .container {
      //display: flex;
      gap: 20px;
    }

    .section {
      flex: 1;
      background: white;
      padding: 15px;
      border-radius: 10px;
      box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    }

    .section h2 {
      color: #333;
      cursor: pointer;
    }

    .subsection {
      margin-left: 15px;
      border-left: 2px solid #eee;
      padding-left: 10px;
    }

    .book-card {
      display: flex;
      gap: 15px;
      background: #fff;
      border-radius: 8px;
      box-shadow: 0 1px 4px rgba(0,0,0,0.1);
      padding: 10px;
      margin-top: 15px;
      text-decoration: none;
      color: inherit;
      transition: transform 0.1s ease-in-out;
    }

    .book-card:hover {
      transform: scale(1.02);
    }

    .book-card img {
      width: 80px;
      height: 120px;
      object-fit: cover;
      border-radius: 4px;
    }

    .book-details {
      flex: 1;
    }

    .book-title {
      font-size: 16px;
      font-weight: bold;
      margin-bottom: 4px;
    }

    .metadata {
      font-size: 14px;
      color: #555;
    }

    .metadata:last-child {
      margin-top: 4px;
    }

    .content-link {
      display: inline-block;
      margin-top: 8px;
      font-size: 13px;
      color: #007BFF;
      cursor: pointer;
    }

/* Modal overlay */
.modal {
  display: none;
  position: fixed;
  z-index: 9999;
  inset: 0;
  backdrop-filter: blur(5px);
  background-color: rgba(0, 0, 0, 0.4);
  animation: fadeIn 0.25s ease-in;
}

/* Modal content wrapper */
.modal-content {
  background: #fff;
  margin: 8vh auto;
  padding: 30px 40px;
  width: 90%;
  max-width: 700px;
  border-radius: 18px;
  box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
  position: relative;
  font-family: "Segoe UI", sans-serif;
  display: flex;
  flex-direction: column;
  animation: slideUp 0.3s ease-out;
}

/* Close button */
.close {
  position: absolute;
  top: 20px;
  right: 25px;
  font-size: 24px;
  color: #888;
  cursor: pointer;
  transition: color 0.2s ease;
}

.close:hover {
  color: #000;
}

/* Modal title */
.modal-content h3 {
  margin-top: 0;
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 10px;
  text-align: left;
  color: #222;
}

/* Book table of contents */
.modal-content ul {
  list-style-type: disc;
  padding-left: 20px;
  margin: 0;
}

.modal-content ul li {
  font-size: 16px;
  line-height: 1.6;
  color: #333;
  margin-bottom: 6px;
  text-align: left;
}

/* Subtle animation */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from { transform: translateY(40px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}

/* Optional: dark mode support */
@media (prefers-color-scheme: dark) {
  .modal-content {
    background: #1e1e1e;
    color: #eee;
  }
  .modal-content h3,
  .modal-content ul li {
    color: #ddd;
  }
  .close {
    color: #aaa;
  }
  .close:hover {
    color: #fff;
  }
}