:root {
  --bg: #f4efe6;
  --paper: #fffdf9;
  --paper-strong: #fff8ef;
  --ink: #2f241b;
  --muted: #756454;
  --line: #ddcfbd;
  --accent: #9a4f2f;
  --accent-soft: #f4d8c6;
  --shadow: 0 24px 60px rgba(67, 44, 20, 0.12);
  --serif: "Georgia", "Times New Roman", serif;
  --sans: "Arial", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top left, rgba(154, 79, 47, 0.18), transparent 28%),
    linear-gradient(180deg, #f8f4ee 0%, var(--bg) 100%);
  color: var(--ink);
  font-family: var(--sans);
}

.app-shell {
  max-width: 1440px;
  margin: 0 auto;
  padding: 32px 20px 40px;
}

.hero {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  align-items: flex-end;
  margin-bottom: 24px;
  padding: 28px;
  border: 1px solid rgba(154, 79, 47, 0.14);
  border-radius: 24px;
  background: rgba(255, 253, 249, 0.86);
  backdrop-filter: blur(10px);
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0 0 10px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  font-size: 0.75rem;
  color: var(--accent);
}

.hero h1,
.form-panel h2,
.pane-header h2,
.book-masthead h1,
.ebook-section h2,
.book-placeholder h2 {
  font-family: var(--serif);
}

.hero h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.3rem);
}

.hero-copy,
.status,
.notes p,
.book-placeholder p {
  color: var(--muted);
}

.hero-actions {
  min-width: 260px;
}

button {
  border: none;
  border-radius: 999px;
  padding: 14px 22px;
  font-size: 0.98rem;
  font-weight: 700;
  cursor: pointer;
}

button.primary {
  width: 100%;
  background: linear-gradient(135deg, #b25d3a, #8f4327);
  color: #fff;
  box-shadow: 0 14px 32px rgba(143, 67, 39, 0.22);
}

button:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.status {
  margin: 12px 4px 0;
  font-size: 0.92rem;
}

.workspace {
  display: grid;
  gap: 24px;
}

.panel {
  background: rgba(255, 253, 249, 0.9);
  border: 1px solid rgba(117, 100, 84, 0.18);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.form-panel {
  padding: 24px;
}

.form-panel-horizontal .field-grid {
  grid-template-columns: repeat(6, minmax(0, 1fr));
  align-items: end;
}

.form-panel-horizontal .notes {
  display: flex;
  gap: 18px;
  align-items: flex-start;
}

.form-panel-horizontal .notes p {
  margin: 0;
  flex: 1;
}

.form-panel h2 {
  margin-top: 0;
  margin-bottom: 18px;
  font-size: 1.45rem;
}

.field-grid {
  display: grid;
  gap: 14px;
}

.field {
  display: grid;
  gap: 8px;
}

.field span {
  font-size: 0.92rem;
  font-weight: 700;
}

.field input {
  width: 100%;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: #fff;
  color: var(--ink);
  font-size: 0.98rem;
}

.field input[type="file"] {
  padding: 10px 12px;
}

.notes {
  margin-top: 18px;
  padding: 16px;
  border-radius: 18px;
  background: var(--paper-strong);
  border: 1px solid rgba(154, 79, 47, 0.1);
}

.preview-panel {
  padding: 18px;
}

.preview-layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 18px;
  min-height: 76vh;
}

.nav-pane,
.content-pane {
  border-radius: 20px;
  overflow: hidden;
}

.nav-pane {
  background: #f8efe4;
  border: 1px solid rgba(154, 79, 47, 0.12);
  display: flex;
  flex-direction: column;
}

.pane-header {
  padding: 18px 18px 14px;
  border-bottom: 1px solid rgba(154, 79, 47, 0.12);
}

.pane-header h2 {
  margin: 0;
  font-size: 1.2rem;
}

.toc-nav {
  max-height: calc(76vh - 64px);
  overflow: auto;
  padding: 12px;
}

.toc-link {
  display: block;
  padding: 10px 12px;
  margin-bottom: 8px;
  border-radius: 12px;
  color: var(--ink);
  text-decoration: none;
  font-size: 0.95rem;
  background: rgba(255, 255, 255, 0.55);
}

.toc-link:hover,
.toc-link.active {
  background: #fff;
  color: var(--accent);
}

.content-pane {
  background: linear-gradient(180deg, #f7f0e7 0%, #fdfbf7 30%, #f8f0e5 100%);
  border: 1px solid rgba(117, 100, 84, 0.16);
  overflow: auto;
}

.book-preview {
  padding: clamp(18px, 4vw, 42px);
}

.book-shell,
.book-export {
  max-width: 860px;
  margin: 0 auto;
  padding: clamp(22px, 4vw, 42px);
  background: var(--paper);
  border-radius: 28px;
  box-shadow: 0 18px 44px rgba(74, 45, 17, 0.12);
}

.book-masthead {
  display: grid;
  grid-template-columns: minmax(160px, 220px) minmax(0, 1fr);
  gap: 28px;
  align-items: center;
  margin-bottom: 36px;
  padding-bottom: 30px;
  border-bottom: 1px solid var(--line);
}

.book-cover {
  width: 100%;
  aspect-ratio: 2 / 3;
  object-fit: cover;
  border-radius: 18px;
  box-shadow: 0 16px 34px rgba(39, 24, 13, 0.18);
  background: #efe5d8;
}

.book-meta p {
  margin: 8px 0 0;
  color: var(--muted);
}

.book-masthead h1 {
  margin: 0;
  font-size: clamp(2rem, 4vw, 3rem);
}

.subtitle {
  display: block;
  margin-top: 10px;
  font-size: clamp(1.05rem, 2vw, 1.4rem);
  color: var(--accent);
}

.ebook-section {
  margin-top: 28px;
  padding-top: 10px;
}

.ebook-section h2 {
  margin-bottom: 18px;
  font-size: 1.75rem;
}

.ebook-section h3,
.ebook-section h4 {
  margin-top: 24px;
  margin-bottom: 12px;
  font-family: var(--serif);
}

.ebook-section p,
.ebook-section li,
.ebook-section blockquote {
  font-family: var(--serif);
  font-size: 1.05rem;
  line-height: 1.75;
}

.ebook-section ul,
.ebook-section ol {
  padding-left: 1.4rem;
}

.ebook-section blockquote {
  margin: 18px 0;
  padding-left: 18px;
  border-left: 4px solid var(--accent-soft);
  color: var(--muted);
}

.empty-state,
.book-placeholder {
  color: var(--muted);
}

.book-placeholder {
  padding: 28px;
  border: 2px dashed rgba(117, 100, 84, 0.22);
  border-radius: 24px;
  background: rgba(255, 255, 255, 0.58);
}

@media (max-width: 1280px) {
  .form-panel-horizontal .field-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 1100px) {
  .preview-layout {
    grid-template-columns: 1fr;
  }

  .toc-nav {
    max-height: none;
  }

  .form-panel-horizontal .notes {
    display: grid;
  }
}

@media (max-width: 720px) {
  .app-shell {
    padding: 16px;
  }

  .hero,
  .book-masthead {
    grid-template-columns: 1fr;
    display: grid;
  }

  .hero {
    align-items: stretch;
  }

  .form-panel-horizontal .field-grid {
    grid-template-columns: 1fr;
  }
}