/* ========================================
   Tractatus Logico-Philosophicus
   Interactive Tree View — light theme
   ======================================== */

/* Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #fafafa;
  --bg-card: #ffffff;
  --bg-hover: #f3f4f6;
  --bg-selected: #ede9fe;
  --bg-header: #ffffff;
  --border: #e5e7eb;
  --border-light: #f0f0f0;

  --text-primary: #1a1a2e;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --text-accent: #7755cc;

  --accent: #7755cc;
  --accent-light: #ede9fe;
  --accent-dark: #5e3aa8;
  --accent-border: #c4b5fd;

  --badge-bg: #fef3c7;
  --badge-text: #92400e;

  --radius: 8px;
  --radius-sm: 4px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.06);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", sans-serif;
  --font-serif: Georgia, "Noto Serif SC", "Source Han Serif SC", serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Fira Code", monospace;

  --tree-indent: 20px;
  --tree-node-height: 36px;
  --transition: 150ms ease;
}

html, body {
  height: 100%;
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
}

/* ---- Header ---- */
.app-header {
  background: var(--bg-header);
  border-bottom: 1px solid var(--border);
  padding: 12px 24px;
  flex-shrink: 0;
  box-shadow: var(--shadow-sm);
  z-index: 10;
}

.header-top {
  display: flex;
  align-items: baseline;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 10px;
}

.title {
  display: flex;
  align-items: baseline;
  gap: 12px;
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
}

.title-zh {
  font-family: var(--font-serif);
  font-size: 1.5rem;
}

.title-en {
  font-family: var(--font-serif);
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--text-muted);
  font-style: italic;
}

.author {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-family: var(--font-serif);
}

.toolbar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.tool-btn {
  padding: 6px 14px;
  font-size: 0.85rem;
  font-family: var(--font-sans);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: background var(--transition), border-color var(--transition);
}
.tool-btn:hover {
  background: var(--bg-hover);
  border-color: var(--accent-border);
}
.tool-btn:active {
  background: var(--bg-selected);
}

.mobile-only { display: none; }

/* ---- Search ---- */
.search-box {
  margin-top: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
  transition: opacity var(--transition);
}
.search-box.hidden {
  display: none;
}
#searchInput {
  flex: 1;
  max-width: 400px;
  padding: 8px 12px;
  font-size: 0.9rem;
  font-family: var(--font-sans);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color var(--transition);
}
#searchInput:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}
.search-count {
  font-size: 0.8rem;
  color: var(--text-secondary);
  white-space: nowrap;
}
.search-clear {
  background: none;
  border: none;
  font-size: 1rem;
  cursor: pointer;
  color: var(--text-muted);
  padding: 4px 8px;
}

/* ---- Main Layout ---- */
.app-main {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.panel-tree {
  width: 380px;
  min-width: 260px;
  border-right: 1px solid var(--border);
  background: var(--bg-card);
  overflow-y: auto;
  overflow-x: auto;
  padding: 12px 0;
  box-shadow: var(--shadow-sm);
  scrollbar-width: thin;
  scrollbar-color: var(--border-light) transparent;
}

.panel-tree::-webkit-scrollbar {
  width: 6px;
}
.panel-tree::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 3px;
}

/* ---- Tree ---- */
.tree {
  font-size: 0.88rem;
  user-select: none;
}

.tree-node {
  position: relative;
}

.tree-row {
  display: flex;
  align-items: center;
  height: var(--tree-node-height);
  cursor: pointer;
  white-space: nowrap;
  transition: background var(--transition);
  padding-right: 12px;
  border-left: 3px solid transparent;
}

.tree-row:hover {
  background: var(--bg-hover);
}

.tree-row.selected {
  background: var(--bg-selected);
  border-left-color: var(--accent);
  color: var(--accent-dark);
  font-weight: 600;
}

.tree-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: var(--tree-node-height);
  flex-shrink: 0;
  font-size: 10px;
  color: var(--text-muted);
  cursor: pointer;
  transition: transform var(--transition), color var(--transition);
}
.tree-toggle:hover {
  color: var(--accent);
}
.tree-toggle.no-children {
  visibility: hidden;
}

.tree-number {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent);
  margin-right: 8px;
  flex-shrink: 0;
  min-width: 60px;
  text-align: right;
}

.tree-text {
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--text-primary);
  line-height: 1.4;
}

.tree-text.untranslated {
  color: var(--text-muted);
  font-style: italic;
}

.tree-text.empty {
  color: var(--text-muted);
  font-size: 0.8rem;
}

.tree-children {
  overflow: hidden;
  max-height: 20000px;
  transition: max-height 350ms ease;
}

.tree-children.collapsed {
  max-height: 0;
}

/* ---- Detail Panel ---- */

.panel-detail {
  flex: 1;
  overflow-y: auto;
  padding: 40px 48px;
  background: var(--bg);
  scrollbar-width: thin;
}

.detail-content {
  max-width: 720px;
}

.detail-content.hidden {
  display: none;
}

/* ---- Tree intro node ---- */
.tree-intro {
  padding: 4px 0;
}

.tree-intro .intro-row {
  border-left: 3px solid transparent;
  padding-left: 5px;
  height: 40px;
  font-size: 0.92rem;
}

.tree-intro .intro-row:hover {
  background: var(--bg-hover);
}

.tree-intro .intro-row.selected {
  background: var(--bg-selected);
  border-left-color: var(--accent);
}

.tree-intro .intro-number {
  font-size: 0.85rem;
  min-width: 24px;
  text-align: center;
  color: var(--text-primary);
  margin-right: 4px;
}

.tree-sep {
  height: 1px;
  margin: 4px 12px 8px;
  background: var(--border-light);
}

/* ---- Intro Content ---- */
.intro-content {
  max-width: 720px;
}

.intro-content.hidden {
  display: none;
}

.intro-hero {
  margin-bottom: 36px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-light);
}

.intro-hero h2 {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.intro-hero-en {
  font-family: var(--font-serif);
  font-size: 0.9rem;
  color: var(--text-muted);
  font-style: italic;
}

.intro-section {
  margin-bottom: 32px;
}

.intro-section h3 {
  font-family: var(--font-sans);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 12px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--border-light);
}

.intro-section h4 {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin: 18px 0 8px;
}

.intro-section p {
  font-family: var(--font-serif);
  font-size: 0.98rem;
  line-height: 1.85;
  color: var(--text-primary);
  margin-bottom: 12px;
  text-align: justify;
}

.intro-section ul,
.intro-section ol {
  margin: 8px 0 16px 20px;
  font-family: var(--font-serif);
  font-size: 0.95rem;
  line-height: 1.8;
  color: var(--text-primary);
}

.intro-section li {
  margin-bottom: 4px;
}

.intro-section strong {
  color: var(--accent-dark);
}

.intro-note {
  margin-top: 24px;
  padding: 14px 18px;
  background: var(--accent-light);
  border-radius: var(--radius);
  border-left: 3px solid var(--accent);
  font-size: 0.9rem !important;
  color: var(--text-secondary) !important;
}

/* ---- Glossary Table ---- */
.glossary-content {
  max-width: 800px;
}

.glossary-note {
  font-family: var(--font-sans) !important;
  font-size: 0.82rem !important;
  color: var(--text-muted) !important;
  padding: 10px 14px;
  background: var(--bg-hover);
  border-radius: var(--radius-sm);
  margin-bottom: 8px !important;
  line-height: 1.5 !important;
}

.glossary-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  margin-top: 16px;
}

.glossary-table thead {
  border-bottom: 2px solid var(--border);
}

.glossary-table th {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 10px 12px;
  text-align: left;
}

.glossary-table td {
  padding: 9px 12px;
  border-bottom: 1px solid var(--border-light);
  font-family: var(--font-serif);
  color: var(--text-primary);
  line-height: 1.6;
}

.glossary-table tr:hover td {
  background: var(--bg-hover);
}

.glossary-table td.germ {
  font-style: italic;
  font-weight: 600;
  color: var(--accent-dark);
}

.glossary-content .intro-hero {
  margin-bottom: 28px;
}

.glossary-content .intro-section {
  margin-bottom: 16px;
}

/* Breadcrumb */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-bottom: 32px;
  font-size: 0.8rem;
  color: var(--text-muted);
  flex-wrap: wrap;
}

.breadcrumb a {
  color: var(--accent);
  text-decoration: none;
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}
.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb .sep {
  color: var(--text-muted);
  margin: 0 2px;
}

.breadcrumb .current {
  color: var(--text-primary);
  font-weight: 600;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

/* Proposition */
.proposition {
  margin-bottom: 40px;
}

.prop-number {
  display: block;
  font-family: var(--font-mono);
  font-size: 1rem;
  color: var(--accent);
  margin-bottom: 16px;
  font-weight: 600;
}

.prop-text {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  line-height: 2.1;
  color: var(--text-primary);
  white-space: pre-line;
}

/* Sub-propositions */
.sub-props {
  margin-top: 48px;
  padding-top: 32px;
  border-top: 1px solid var(--border-light);
}

.sub-props-title {
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 24px;
}

.sub-prop-item {
  padding: 14px 0;
  border-bottom: 1px solid var(--border-light);
  cursor: pointer;
  transition: background var(--transition);
}

.sub-prop-item:last-child {
  border-bottom: none;
}

.sub-prop-item:hover {
  background: var(--bg-hover);
  margin: 0 -12px;
  padding-left: 12px;
  padding-right: 12px;
  border-radius: var(--radius-sm);
}

.sub-prop-num {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--accent);
  display: block;
  margin-bottom: 4px;
}

.sub-prop-text {
  font-family: var(--font-serif);
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.sub-prop-text.untranslated {
  color: var(--text-muted);
  font-style: italic;
}

.sub-prop-text.empty {
  color: var(--text-muted);
  font-size: 0.82rem;
}

/* Original text toggle */
.original-section {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
}

.original-toggle {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  color: var(--accent);
  background: none;
  border: 1px solid var(--accent-border);
  border-radius: var(--radius-sm);
  padding: 6px 14px;
  cursor: pointer;
  transition: background var(--transition);
}
.original-toggle:hover {
  background: var(--bg-selected);
}

.toggle-icon {
  display: inline-block;
  transition: transform var(--transition);
  font-size: 0.7rem;
}

.original-toggle.open .toggle-icon {
  transform: rotate(90deg);
}

.original-text.hidden {
  display: none;
}

.original-text {
  margin-top: 16px;
}

.original-lang {
  margin-bottom: 16px;
}

.original-lang h4 {
  font-family: var(--font-sans);
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.original-lang p {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.8;
  color: var(--text-secondary);
  white-space: pre-line;
}

/* Detail nav */
.detail-nav {
  display: flex;
  gap: 12px;
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
  flex-wrap: wrap;
}

.nav-btn {
  font-family: var(--font-sans);
  font-size: 0.85rem;
  padding: 8px 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--transition);
}
.nav-btn:hover {
  border-color: var(--accent-border);
  background: var(--bg-selected);
}
.nav-btn:disabled {
  opacity: 0.35;
  cursor: default;
  background: var(--bg-card);
  border-color: var(--border);
}

/* Translation badge */
.translation-badge {
  display: inline-block;
  margin-top: 16px;
  padding: 3px 10px;
  font-size: 0.78rem;
  background: var(--badge-bg);
  color: var(--badge-text);
  border-radius: 999px;
  font-family: var(--font-sans);
}
.translation-badge.hidden {
  display: none;
}

/* ============ Responsive ============ */
@media (max-width: 768px) {
  .app-header {
    padding: 10px 16px;
  }

  .title {
    font-size: 1.1rem;
  }
  .title-en {
    font-size: 0.7rem;
  }

  .mobile-only { display: inline-block; }

  .app-main {
    flex-direction: column;
  }

  .panel-tree {
    width: 100%;
    min-width: unset;
    border-right: none;
    border-bottom: 1px solid var(--border);
    max-height: 45vh;
  }

  .panel-tree.hidden-mobile {
    display: none;
  }

  .panel-detail {
    flex: 1;
    padding: 20px 16px;
  }

  .panel-detail.hidden-mobile {
    display: none;
  }

  .prop-text {
    font-size: 1.05rem;
    line-height: 1.8;
  }

  .intro-hero h2 {
    font-size: 1.3rem;
  }

  .intro-section p {
    font-size: 0.9rem;
  }
}

@media (max-width: 480px) {
  .toolbar {
    gap: 4px;
  }
  .tool-btn {
    padding: 5px 10px;
    font-size: 0.78rem;
  }

  .detail-nav {
    flex-direction: column;
  }
}