:root {
    --gold: #C9A84C;
    --gold-light: #E8D5A3;
    --gold-dim: #8B6914;
    --ink: #1A1814;
    --ink-mid: #3D3A32;
    --ink-soft: #6B6558;
    --parchment: #FAF7F0;
    --parchment-mid: #F0EBE0;
    --parchment-dark: #E5DDD0;
    --border: rgba(201,168,76,0.25);
    --border-strong: rgba(201,168,76,0.5);
    --accent-blue: #2E5B8A;
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  body {
    font-family: 'Source Serif 4', Georgia, serif;
    background: var(--parchment);
    color: var(--ink);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
  }

  header {
    background: var(--ink);
    padding: 0.35rem 2rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    border-bottom: 2px solid var(--gold);
    position: sticky;
    top: 0;
    z-index: 100;
  }

  .header-logo {
    height: 44px;
    width: auto;
    display: block;
  }

  nav {
    margin-left: 0;
    display: flex;
    gap: 0.25rem;
  }

  nav button {
    background: none;
    border: none;
    color: #8B8070;
    font-family: 'Source Serif 4', serif;
    font-size: 1rem;
    cursor: pointer;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: all 0.2s;
    letter-spacing: 0.03em;
  }

  nav button:hover, nav button.active {
    color: var(--gold-light);
    background: rgba(201,168,76,0.1);
  }

  main { flex: 1; display: flex; flex-direction: column; }

  .hero {
    background: var(--ink);
    padding: 0;
    text-align: center;
    border-bottom: 1px solid var(--border);
    position: relative;
    overflow: hidden;
  }

  .hero-logo-banner {
    width: 88%;
    max-width: 980px;
    height: auto;
    display: block;
    margin: 0.5rem auto 0;
    opacity: 0.95;
  }

  .hero-overlay {
    background: linear-gradient(to bottom, transparent 40%, var(--ink) 100%);
    position: absolute;
    bottom: 0; left: 0; right: 0;
    height: 60%;
  }

  .hero-text {
    position: relative;
    padding: 0 2rem 2rem;
    background: var(--ink);
  }

  .hero-desc {
    color: var(--gold-light);
    font-size: 1.1rem;
    font-style: italic;
    max-width: 680px;
    margin: 0 auto;
    line-height: 1.4;
    letter-spacing: 0.02em;
  }

  .search-area {
    background: var(--ink);
    padding: 1.5rem 2rem 2.5rem;
  }

  .search-box { max-width: 700px; margin: 0 auto; }

  .input-row {
    display: flex;
    border: 1.5px solid var(--border-strong);
    border-radius: 6px;
    overflow: hidden;
    background: #12100E;
    transition: border-color 0.2s;
  }

  .input-row:focus-within { border-color: var(--gold); }

  #question-input {
    flex: 1;
    background: none;
    border: none;
    outline: none;
    color: #F0EBE0;
    font-family: 'Source Serif 4', serif;
    font-size: 1rem;
    padding: 0.9rem 1.25rem;
    min-height: 52px;
  }

  #question-input::placeholder { color: #4A453C; }

  #ask-btn {
    background: var(--gold);
    border: none;
    color: var(--ink);
    font-family: 'Source Serif 4', serif;
    font-size: 0.85rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 0 1.5rem;
    cursor: pointer;
    transition: background 0.2s;
    white-space: nowrap;
  }

  #ask-btn:hover { background: var(--gold-light); }
  #ask-btn:disabled { background: #4A453C; cursor: not-allowed; color: #2A2520; }

  .book-filters {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    margin-top: 0.85rem;
    justify-content: center;
  }

  .book-chip {
    background: none;
    border: 1px solid rgba(201,168,76,0.2);
    color: #6B6558;
    font-family: 'Source Serif 4', serif;
    font-size: 0.72rem;
    letter-spacing: 0.04em;
    padding: 0.3rem 0.75rem;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s;
  }

  .book-chip.active {
    border-color: var(--gold);
    color: var(--gold-light);
    background: rgba(201,168,76,0.08);
  }

  .guided-section {
    padding: 2rem;
    border-bottom: 1px solid var(--parchment-dark);
  }

  .section-label {
    font-size: 0.68rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-soft);
    margin-bottom: 1rem;
    text-align: center;
  }

  .books-hero-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1rem;
    max-width: 960px;
    margin: 0 auto;
  }

  .book-hero-btn {
    display: block;
    border-radius: 10px;
    overflow: hidden;
    border: 1px solid var(--parchment-dark);
    transition: all 0.2s;
  }

  .book-hero-btn:hover {
    border-color: var(--gold);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(201,168,76,0.2);
  }

  .book-hero-btn img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
  }

  .paths-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(195px, 1fr));
    gap: 0.65rem;
    max-width: 900px;
    margin: 0 auto;
  }

  .path-btn {
    background: white;
    border: 1px solid var(--parchment-dark);
    border-radius: 6px;
    padding: 0.85rem 1rem;
    cursor: pointer;
    text-align: left;
    transition: all 0.2s;
    font-family: 'Source Serif 4', serif;
  }

  .path-btn:hover {
    border-color: var(--gold);
    background: #FFFDF8;
    transform: translateY(-1px);
    box-shadow: 0 3px 12px rgba(201,168,76,0.12);
  }

  .path-icon { font-size: 1.1rem; margin-bottom: 0.4rem; display: block; }
  .path-text { font-size: 0.85rem; color: var(--ink-mid); line-height: 1.4; }
  .path-book { font-size: 0.68rem; color: var(--ink-soft); margin-top: 0.25rem; }

  .response-area {
    flex: 1;
    padding: 2rem 2rem 8rem;
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
  }

  .response-placeholder {
    text-align: center;
    padding: 3rem 1rem;
  }

  .response-placeholder .big-quote {
    font-family: 'Playfair Display', serif;
    font-size: 4rem;
    color: var(--parchment-dark);
    line-height: 1;
    margin-bottom: 0.5rem;
  }

  .response-placeholder p {
    font-size: 0.9rem;
    font-style: italic;
    color: var(--ink-soft);
  }

  .answer-card {
    background: white;
    border: 1px solid var(--parchment-dark);
    border-radius: 8px;
    overflow: hidden;
    animation: fadeUp 0.3s ease;
  }

  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .answer-header {
    background: var(--parchment-mid);
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--parchment-dark);
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
  }

  .investigator-tag {
    font-size: 0.68rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--gold-dim);
    background: rgba(201,168,76,0.12);
    border: 1px solid rgba(201,168,76,0.3);
    padding: 0.2rem 0.6rem;
    border-radius: 3px;
    white-space: nowrap;
    margin-top: 2px;
  }

  .answer-question {
    font-family: 'Playfair Display', serif;
    font-size: 1.05rem;
    color: var(--ink);
    font-style: italic;
    line-height: 1.4;
  }

  .answer-body {
    padding: 1.5rem;
    font-size: 0.97rem;
    line-height: 1.85;
    color: var(--ink-mid);
  }

  .answer-body p { margin-bottom: 1rem; }
  .answer-body p:last-child { margin-bottom: 0; }

  .citation-tag {
    display: inline-block;
    background: rgba(46,91,138,0.08);
    border: 1px solid rgba(46,91,138,0.2);
    color: var(--accent-blue);
    font-size: 0.7rem;
    padding: 0.1rem 0.45rem;
    border-radius: 3px;
    letter-spacing: 0.03em;
    vertical-align: middle;
    margin-left: 3px;
  }

  .answer-footer {
    padding: 1rem 1.5rem;
    background: #FDFCF8;
    border-top: 1px solid var(--parchment-dark);
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
  }

  .follow-up-btn {
    background: none;
    border: 1px solid var(--parchment-dark);
    color: var(--ink-soft);
    font-family: 'Source Serif 4', serif;
    font-size: 0.78rem;
    padding: 0.35rem 0.85rem;
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.2s;
    font-style: italic;
  }

  .follow-up-btn:hover { border-color: var(--gold); color: var(--gold-dim); }

  .loading-state { text-align: center; padding: 3rem; color: var(--ink-soft); }

  .loading-dots { display: inline-flex; gap: 6px; margin-bottom: 1rem; }

  .loading-dots span {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--gold);
    animation: pulse 1.4s infinite;
  }

  .loading-dots span:nth-child(2) { animation-delay: 0.2s; }
  .loading-dots span:nth-child(3) { animation-delay: 0.4s; }

  @keyframes pulse {
    0%, 80%, 100% { opacity: 0.2; transform: scale(0.8); }
    40% { opacity: 1; transform: scale(1); }
  }

  .loading-text { font-style: italic; font-size: 0.9rem; }

  .books-page { padding: 2rem; max-width: 860px; margin: 0 auto; width: 100%; }

  .books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.25rem;
    margin-top: 1.5rem;
  }

  .book-card {
    background: white;
    border: 1px solid var(--parchment-dark);
    border-radius: 8px;
    padding: 1.5rem;
    transition: all 0.2s;
  }

  .book-card:hover {
    border-color: var(--gold);
    box-shadow: 0 4px 16px rgba(201,168,76,0.1);
  }

  .book-num { font-size: 0.68rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--gold-dim); margin-bottom: 0.5rem; }
  .book-title-card { font-family: 'Playfair Display', serif; font-size: 1.1rem; color: var(--ink); margin-bottom: 0.5rem; line-height: 1.3; }
  .book-desc { font-size: 0.83rem; color: var(--ink-soft); line-height: 1.65; font-style: italic; }

  .book-explore-btn {
    margin-top: 1rem;
    background: none;
    border: 1px solid var(--parchment-dark);
    color: var(--ink-soft);
    font-family: 'Source Serif 4', serif;
    font-size: 0.78rem;
    padding: 0.4rem 1rem;
    border-radius: 4px;
    cursor: pointer;
    transition: all 0.2s;
  }

  .book-explore-btn:hover { border-color: var(--gold); color: var(--gold-dim); }

  .about-page { padding: 2rem; max-width: 680px; margin: 0 auto; width: 100%; }
  .about-page h2 { font-family: 'Playfair Display', serif; font-size: 1.6rem; font-weight: 400; margin-bottom: 1.25rem; }
  .about-page p { font-size: 0.95rem; line-height: 1.85; color: var(--ink-mid); margin-bottom: 1.1rem; }
  .about-page em { color: var(--gold-dim); font-style: italic; }

  .error-state {
    background: #FFF8F8;
    border: 1px solid #F0D0D0;
    border-radius: 6px;
    padding: 1.25rem 1.5rem;
    color: #8B3030;
    font-size: 0.9rem;
  }

  @media (max-width: 600px) {
    header { padding: 0.6rem 1rem; }
    .hero-logo-banner { max-height: 200px; }
    nav button { font-size: 0.72rem; padding: 0.3rem 0.5rem; }
    .search-area { padding: 1rem 1rem 2rem; }
    .guided-section { padding: 1.5rem 1rem; }
    .response-area, .books-page, .about-page { padding: 1.25rem 1rem; }
    .paths-grid { grid-template-columns: 1fr 1fr; }
    .books-hero-grid { grid-template-columns: 1fr 1fr; gap: 0.75rem; }
  }