/* --- DESIGN SYSTEM & CSS VARIABLES --- */
:root {
  --font-base: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-scale: 100%;

  /* Dark Theme (Default) */
  --bg-app: #090D16;
  --bg-surface: #111827;
  --bg-surface-elevated: #1F2937;
  --border-color: #374151;
  --border-subtle: #1F2937;
  --text-main: #F9FAFB;
  --text-muted: #9CA3AF;
  --text-dim: #6B7280;
  --accent: #14B8A6;
  --accent-hover: #2DD4BF;
  --accent-badge: rgba(20, 184, 166, 0.15);
  --gold: #F59E0B;
  --gold-bg: rgba(245, 158, 11, 0.1);
}

/* Light Theme */
html[data-theme="light"] {
  --bg-app: #F8FAFC;
  --bg-surface: #FFFFFF;
  --bg-surface-elevated: #F1F5F9;
  --border-color: #CBD5E1;
  --border-subtle: #E2E8F0;
  --text-main: #0F172A;
  --text-muted: #475569;
  --text-dim: #64748B;
  --accent: #0D9488;
  --accent-hover: #0F766E;
  --accent-badge: rgba(13, 148, 136, 0.12);
  --gold: #D97706;
  --gold-bg: rgba(217, 119, 6, 0.1);
}

/* Sepia / Warm Paper Theme */
html[data-theme="sepia"] {
  --bg-app: #F4EFEA;
  --bg-surface: #EBE3DA;
  --bg-surface-elevated: #DDD2C4;
  --border-color: #C8BAA8;
  --border-subtle: #D8CCC0;
  --text-main: #2D2421;
  --text-muted: #645550;
  --text-dim: #8B7872;
  --accent: #B45309;
  --accent-hover: #92400E;
  --accent-badge: rgba(180, 83, 9, 0.15);
  --gold: #B45309;
  --gold-bg: rgba(180, 83, 9, 0.1);
}

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

html {
  font-size: var(--font-scale);
  background-color: var(--bg-app);
  color: var(--text-main);
  transition: background-color 0.2s ease, color 0.2s ease;
}

body {
  font-family: var(--font-base);
  background-color: var(--bg-app);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Top Header */
header.app-header {
  height: 60px;
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  position: sticky;
  top: 0;
  z-index: 100;
}

.brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--text-main);
  text-decoration: none;
}

.brand .pill {
  font-size: 0.65rem;
  background-color: var(--accent-badge);
  color: var(--accent);
  padding: 2px 8px;
  border-radius: 999px;
  text-transform: uppercase;
  font-weight: 700;
  letter-spacing: 0.05em;
}

.header-center {
  flex: 1;
  max-width: 440px;
  margin: 0 24px;
}

.search-btn {
  width: 100%;
  background-color: var(--bg-app);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 8px 14px;
  border-radius: 8px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  cursor: pointer;
  transition: border-color 0.15s;
}
.search-btn:hover { border-color: var(--accent); }
.search-btn kbd {
  background: var(--bg-surface-elevated);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.75rem;
  color: var(--text-dim);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-btn {
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-main);
  padding: 7px 12px;
  border-radius: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all 0.15s;
}
.nav-btn:hover { background-color: var(--bg-surface-elevated); }
.nav-btn.primary {
  background-color: var(--accent);
  border-color: var(--accent);
  color: #FFFFFF;
}
.nav-btn.primary:hover { background-color: var(--accent-hover); }

/* Main Container Grid */
.app-container {
  display: grid;
  grid-template-columns: 280px 1fr 240px;
  flex: 1;
  max-width: 1600px;
  margin: 0 auto;
  width: 100%;
  background-color: var(--bg-app);
}

/* Left Sidebar */
aside.app-sidebar {
  background-color: var(--bg-surface);
  border-right: 1px solid var(--border-color);
  padding: 20px 14px;
  overflow-y: auto;
  height: calc(100vh - 60px);
  position: sticky;
  top: 60px;
}

.sidebar-section-title {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  font-weight: 700;
  margin: 20px 8px 8px;
}

.nav-tree-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 10px;
  margin-bottom: 2px;
  border-radius: 6px;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: all 0.15s;
}
.nav-tree-item:hover {
  background-color: var(--bg-surface-elevated);
  color: var(--text-main);
}
.nav-tree-item.active {
  background-color: var(--accent-badge);
  color: var(--accent);
  font-weight: 600;
}
.nav-tree-sub {
  margin-left: 12px;
  border-left: 1px solid var(--border-color);
  padding-left: 8px;
  margin-bottom: 6px;
}

/* Center Content Viewport */
main.app-content {
  padding: 40px 48px;
  display: flex;
  flex-direction: column;
  align-items: center;
  background-color: var(--bg-app);
}

.article-wrapper {
  width: 100%;
  max-width: 820px;
}

.breadcrumbs {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}
.breadcrumbs a {
  color: inherit;
  text-decoration: none;
}
.breadcrumbs a:hover {
  color: var(--accent);
}

.article-header {
  margin-bottom: 28px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 20px;
}
.article-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 12px;
  color: var(--text-main);
}
.article-meta {
  display: flex;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.prose {
  font-size: 1.05rem;
  line-height: 1.8;
  color: var(--text-main);
}
.prose p { margin-bottom: 1.4em; }
.prose h2 {
  font-size: 1.55rem;
  font-weight: 700;
  margin: 1.8em 0 0.6em;
  color: var(--text-main);
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 6px;
}
.prose h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin: 1.4em 0 0.4em;
  color: var(--text-main);
}
.prose ul, .prose ol {
  margin: 0 0 1.4em 1.6em;
}
.prose li {
  margin-bottom: 0.4em;
}

.medical-disclaimer {
  background-color: var(--gold-bg);
  border: 1px solid var(--gold);
  border-left: 5px solid var(--gold);
  border-radius: 8px;
  padding: 16px 20px;
  margin-top: 48px;
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--text-main);
}

/* Right Table of Contents */
aside.app-toc {
  background-color: var(--bg-surface);
  border-left: 1px solid var(--border-color);
  padding: 24px 18px;
  overflow-y: auto;
  height: calc(100vh - 60px);
  position: sticky;
  top: 60px;
}
.toc-title {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  font-weight: 700;
  margin-bottom: 12px;
}
.toc-link {
  display: block;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-decoration: none;
  padding: 5px 0;
  transition: color 0.15s;
}
.toc-link:hover { color: var(--accent); }

/* Modals */
.modal-overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(4px);
  display: grid;
  place-items: center;
  z-index: 200;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.modal-overlay.open {
  opacity: 1;
  pointer-events: auto;
}
.modal-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  width: 100%;
  max-width: 440px;
  padding: 24px;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.5);
}
.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}
.modal-close {
  background: transparent;
  border: none;
  font-size: 1.4rem;
  color: var(--text-muted);
  cursor: pointer;
}
.setting-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  border-bottom: 1px solid var(--border-subtle);
}
.theme-selector { display: flex; gap: 6px; }
.theme-btn {
  padding: 6px 12px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background-color: var(--bg-app);
  color: var(--text-main);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.15s;
}
.theme-btn.active {
  border-color: var(--accent);
  background-color: var(--accent-badge);
  color: var(--accent);
  font-weight: 700;
}

/* Hidden elements on desktop */
.drawer-backdrop, .mobile-toc-details, .mobile-bottom-nav, .mobile-menu-btn, .mobile-close-btn {
  display: none;
}

/* Responsive Breakpoints */
@media (max-width: 1100px) {
  .app-container { grid-template-columns: 260px 1fr; }
  aside.app-toc { display: none; }
  .mobile-toc-details {
    display: block;
    background-color: var(--bg-surface);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 12px 16px;
    margin-bottom: 24px;
  }
  .mobile-toc-details summary {
    cursor: pointer;
    font-weight: 600;
    color: var(--accent);
  }
}

@media (max-width: 768px) {
  .app-container { grid-template-columns: 1fr; }
  aside.app-sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    height: 100vh;
    width: 82vw;
    max-width: 300px;
    transform: translateX(-100%);
    transition: transform 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 150;
    box-shadow: 10px 0 30px rgba(0,0,0,0.5);
  }
  aside.app-sidebar.open { transform: translateX(0); }
  .mobile-menu-btn, .mobile-close-btn { display: inline-block; }
  .drawer-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.7);
    z-index: 140;
  }
  .drawer-backdrop.active { display: block; }
  header.app-header { padding: 0 14px; }
  .header-center { display: none; }
  .header-actions .nav-btn:not(.primary) { display: none; }
  main.app-content { padding: 24px 16px 80px 16px; }
  .mobile-bottom-nav {
    display: flex;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    height: 58px;
    background-color: var(--bg-surface);
    border-top: 1px solid var(--border-color);
    z-index: 100;
    justify-content: space-around;
    align-items: center;
  }
  .mobile-nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 3px;
    font-size: 0.7rem;
    color: var(--text-muted);
    background: transparent;
    border: none;
    cursor: pointer;
  }
  .mobile-nav-item.active { color: var(--accent); }
}

/* --- DUAL TONE (PLAIN vs ACADEMIC) STYLING --- */
.tone-toggle-wrapper {
  display: inline-flex;
  background-color: var(--bg-app);
  border: 1px solid var(--border-color);
  border-radius: 999px;
  padding: 3px;
  gap: 2px;
}

.tone-pill-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-size: 0.78rem;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: 999px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 5px;
  transition: all 0.15s ease;
}

.tone-pill-btn.active {
  background-color: var(--accent);
  color: #FFFFFF;
}

.mobile-tone-bar {
  display: none;
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  padding: 8px 14px;
  justify-content: space-between;
  align-items: center;
}

@media (max-width: 768px) {
  .mobile-tone-bar {
    display: flex;
  }
  header.app-header .tone-toggle-wrapper {
    display: none;
  }
}

/* Visibility Rules Based on data-mode */
html[data-mode="plain"] .mode-academic {
  display: none !important;
}

html[data-mode="academic"] .mode-plain {
  display: none !important;
}

/* Tone Notice Banner for Whole Articles */
.tone-notice-banner {
  padding: 12px 16px;
  border-radius: 8px;
  margin-bottom: 24px;
  font-size: 0.88rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.tone-notice-academic {
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: #60A5FA;
}

.tone-notice-plain {
  background: rgba(16, 185, 129, 0.1);
  border: 1px solid rgba(16, 185, 129, 0.3);
  color: #34D399;
}

/* In-Content Tone Fences */
.tone-block {
  margin: 18px 0;
  padding: 18px 22px;
  border-radius: 8px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
}

.tone-block.mode-plain {
  border-left: 4px solid #10B981;
}

.tone-block.mode-academic {
  border-left: 4px solid #3B82F6;
}

.tone-block-badge {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 4px;
  margin-bottom: 10px;
}

.mode-plain .tone-block-badge {
  background: rgba(16, 185, 129, 0.15);
  color: #10B981;
}

.mode-academic .tone-block-badge {
  background: rgba(59, 130, 246, 0.15);
  color: #3B82F6;
}