/* ==========================================================================
   ATOMVERSE - Museum-Quality Design System
   Palette: Deep Midnight Ink & Heritage Olive Green
   Accents: Warm Brass Nucleus, Sage/Teal bonds, Sumi Ink Typography
   Themes: Full Dark Mode (Deep Ink) & Light Mode (Ivory Paper / Ink)
   100% Offline, Zero external CDN dependencies, 200-400ms smooth transitions.
   ========================================================================== */

:root,
:root[data-theme="dark"],
html[data-theme="dark"],
body[data-theme="dark"],
[data-theme="dark"] {
  /* Dark Mode Default (Deep Midnight Ink & Heritage Olive) */
  --bg-core: #090e13;
  --bg-surface: #0e1620;
  --bg-card: #131e2b;
  --bg-card-hover: #192737;
  --bg-card-active: #1f3145;
  --bg-overlay: rgba(9, 14, 19, 0.88);

  --border-subtle: #1c2b3a;
  --border-medium: #263c4f;
  --border-bright: #708d32;
  --border-focus: #8dae46;

  --accent-olive: #708d32;
  --accent-olive-bright: #8dae46;
  --accent-olive-muted: #4e6720;
  --accent-olive-glow: rgba(112, 141, 50, 0.25);
  --accent-olive-soft: rgba(112, 141, 50, 0.14);
  --accent-olive-subtle: rgba(112, 141, 50, 0.08);

  --accent-amber: #d97706;
  --accent-amber-bright: #f59e0b;
  --accent-amber-muted: #92400e;
  --accent-amber-glow: rgba(217, 119, 6, 0.25);
  --accent-amber-soft: rgba(245, 158, 11, 0.14);

  --accent-cyan: #3b9b88;
  --accent-cyan-bright: #52c2ad;
  --accent-cyan-muted: #1e6b5d;
  --accent-cyan-glow: rgba(59, 155, 136, 0.25);
  --accent-cyan-soft: rgba(59, 155, 136, 0.14);

  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --text-inverse: #090e13;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.5);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.6);
  --shadow-glow-amber: 0 0 20px rgba(245, 158, 11, 0.2);
  --shadow-glow-cyan: 0 0 20px rgba(82, 194, 173, 0.2);
  --shadow-glow-olive: 0 0 20px rgba(112, 141, 50, 0.25);

  --gradient-primary: linear-gradient(135deg, #4e6720 0%, #708d32 100%);
  --gradient-primary-hover: linear-gradient(135deg, #40551a 0%, #5d7827 100%);
  --gradient-hero-title: linear-gradient(135deg, #f59e0b 0%, #8dae46 50%, #52c2ad 100%);
  --gradient-card-hero: linear-gradient(135deg, #0e1722 0%, #152230 100%);
  --gradient-card-identity: linear-gradient(135deg, #101c26 0%, #162635 100%);
  --gradient-avatar: linear-gradient(135deg, #4e6720 0%, #0e1620 100%);
  --gradient-avatar-large: linear-gradient(135deg, #38531a 0%, #708d32 50%, #d97706 100%);

  --transition-fast: 180ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 280ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme (Ivory Paper & Rich Fountain Ink + Heritage Olive) */
:root[data-theme="light"],
html[data-theme="light"],
body[data-theme="light"],
[data-theme="light"],
.light-mode,
body.light-mode {
  --bg-core: #f5f8f5;
  --bg-surface: #ffffff;
  --bg-card: #ffffff;
  --bg-card-hover: #edf3ed;
  --bg-card-active: #e2ede2;
  --bg-overlay: rgba(245, 248, 245, 0.92);

  --border-subtle: #e2e8f0;
  --border-medium: #cbd5e1;
  --border-bright: #4f7324;
  --border-focus: #638b2c;

  --accent-olive: #4f7324;
  --accent-olive-bright: #638b2c;
  --accent-olive-muted: #38531a;
  --accent-olive-glow: rgba(79, 115, 36, 0.2);
  --accent-olive-soft: rgba(79, 115, 36, 0.1);
  --accent-olive-subtle: rgba(79, 115, 36, 0.05);

  --accent-amber: #b45309;
  --accent-amber-bright: #d97706;
  --accent-amber-muted: #78350f;
  --accent-amber-glow: rgba(180, 83, 9, 0.18);
  --accent-amber-soft: rgba(180, 83, 9, 0.09);

  --accent-cyan: #1e7061;
  --accent-cyan-bright: #2d8f7d;
  --accent-cyan-muted: #134e43;
  --accent-cyan-glow: rgba(30, 112, 97, 0.18);
  --accent-cyan-soft: rgba(30, 112, 97, 0.09);

  --text-primary: #0b1319;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  --shadow-sm: 0 1px 3px rgba(11, 19, 25, 0.06);
  --shadow-md: 0 4px 16px -2px rgba(11, 19, 25, 0.08);
  --shadow-lg: 0 12px 28px -4px rgba(11, 19, 25, 0.12);
  --shadow-glow-amber: 0 0 16px rgba(217, 119, 6, 0.15);
  --shadow-glow-cyan: 0 0 16px rgba(30, 112, 97, 0.15);
  --shadow-glow-olive: 0 0 16px rgba(79, 115, 36, 0.18);

  --gradient-primary: linear-gradient(135deg, #38531a 0%, #4f7324 100%);
  --gradient-primary-hover: linear-gradient(135deg, #2d4215 0%, #405d1c 100%);
  --gradient-hero-title: linear-gradient(135deg, #b45309 0%, #4f7324 50%, #1e7061 100%);
  --gradient-card-hero: linear-gradient(135deg, #ffffff 0%, #f4f8f4 100%);
  --gradient-card-identity: linear-gradient(135deg, #ffffff 0%, #f0f6f0 100%);
  --gradient-avatar: linear-gradient(135deg, #4f7324 0%, #f0f4f0 100%);
  --gradient-avatar-large: linear-gradient(135deg, #38531a 0%, #4f7324 50%, #d97706 100%);
}

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

html {
  scroll-behavior: smooth;
  color-scheme: dark light;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-core);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  position: relative;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Custom Selection */
::selection {
  background-color: var(--accent-olive);
  color: #ffffff;
}

/* Ambient Canvas Background */
#ambient-bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
  opacity: 0.65;
  transition: opacity var(--transition-normal);
}

[data-theme="light"] #ambient-bg-canvas {
  opacity: 0.45;
}

/* Layout Containers */
.app-wrapper {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.main-content {
  max-width: 1320px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

section {
  padding: 80px 0;
  border-bottom: 1px solid var(--border-subtle);
  position: relative;
  transition: border-color var(--transition-normal);
}

section:last-of-type {
  border-bottom: none;
}

/* Typography & Section Headers */
h1, h2, h3, h4, h5 {
  color: var(--text-primary);
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.section-header {
  text-align: center;
  max-width: 780px;
  margin: 0 auto 48px auto;
}

.section-badge {
  display: inline-block;
  margin-bottom: 12px;
}

.section-title {
  font-size: 2.3rem;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
  color: var(--text-primary);
}

.section-desc {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.gradient-text {
  background: var(--gradient-hero-title);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Reusable Badges & Chips */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  transition: all var(--transition-fast);
}

.badge-amber {
  background: var(--accent-amber-soft);
  color: var(--accent-amber-bright);
  border: 1px solid var(--accent-amber-glow);
}

.badge-olive {
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  border: 1px solid var(--accent-olive-glow);
}

.badge-cyan {
  background: var(--accent-cyan-soft);
  color: var(--accent-cyan-bright);
  border: 1px solid var(--accent-cyan-glow);
}

.pulse-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: var(--accent-olive-bright);
  box-shadow: 0 0 8px var(--accent-olive-bright);
  animation: pulseAnim 2s infinite ease-in-out;
}

@keyframes pulseAnim {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.4); opacity: 0.6; }
}

/* Reusable Cards & Surfaces */
.card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-md);
  transition: background-color var(--transition-normal), border-color var(--transition-normal), box-shadow var(--transition-normal);
}

.card:hover {
  border-color: var(--border-medium);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.btn-primary {
  background: var(--gradient-primary);
  color: #ffffff;
  border-color: var(--accent-olive-bright);
  box-shadow: 0 2px 8px var(--accent-olive-glow);
}

.btn-primary:hover {
  background: var(--gradient-primary-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 14px var(--accent-olive-glow);
}

.btn-secondary {
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  border-color: var(--accent-olive-glow);
}

.btn-secondary:hover {
  background: var(--accent-olive-glow);
  border-color: var(--accent-olive-bright);
}

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border-color: var(--border-medium);
}

.btn-outline:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-olive);
  color: var(--accent-olive-bright);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
}

.btn-ghost:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
}

.btn-sm {
  padding: 6px 14px;
  font-size: 0.82rem;
}

.btn-xs {
  padding: 5px 11px;
  font-size: 0.76rem;
}

.btn-icon {
  width: 34px;
  height: 34px;
  padding: 0;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border-medium);
  color: var(--text-primary);
  font-size: 1.1rem;
}

.btn-icon:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-olive);
  color: var(--accent-olive-bright);
}

.w-100 { width: 100%; }

/* Color Highlights */
.text-amber { color: var(--accent-amber-bright) !important; }
.text-cyan { color: var(--accent-cyan-bright) !important; }
.text-olive { color: var(--accent-olive-bright) !important; }
.text-slate { color: var(--text-secondary) !important; }
.text-neutral { color: var(--text-primary) !important; }

/* Persistent Navigation Bar */
.navbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--bg-overlay);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 12px 24px;
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.nav-inner {
  max-width: 1320px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-primary);
}

.nav-logo-icon {
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent-olive) 0%, var(--accent-amber) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 10px var(--accent-olive-glow);
}

.nav-brand-title {
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.nav-brand-tag {
  font-size: 0.72rem;
  color: var(--accent-olive-bright);
  background: var(--accent-olive-soft);
  padding: 2px 6px;
  border-radius: 4px;
  font-weight: 600;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 6px;
  list-style: none;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.nav-link:hover {
  color: var(--text-primary);
  background: var(--bg-card-hover);
}

.nav-link.active {
  color: var(--accent-olive-bright);
  background: var(--accent-olive-soft);
  border: 1px solid var(--accent-olive-glow);
  font-weight: 600;
}

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

.theme-icon-slot {
  display: flex;
  align-items: center;
  justify-content: center;
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero-container {
  text-align: center;
  padding: 30px 0 20px 0;
}

.hero-header-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: var(--accent-olive-soft);
  border: 1px solid var(--accent-olive-glow);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  color: var(--accent-olive-bright);
  font-weight: 600;
  margin-bottom: 20px;
}

.hero-title {
  font-size: 3.4rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 16px;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 740px;
  margin: 0 auto 36px auto;
}

.zoom-stepper-wrapper {
  max-width: 1000px;
  margin: 0 auto;
}

.zoom-stepper-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 12px;
}

.zoom-step-indicator {
  display: flex;
  gap: 10px;
}

.zoom-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.zoom-track {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
  margin-bottom: 24px;
}

.zoom-step-node {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 10px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.zoom-step-node:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  color: var(--text-primary);
}

.zoom-step-node.active {
  background: var(--accent-olive-soft);
  border-color: var(--accent-olive);
  color: var(--accent-olive-bright);
  box-shadow: 0 0 10px var(--accent-olive-glow);
}

.step-num {
  font-size: 0.75rem;
  font-weight: 700;
  opacity: 0.7;
}

.step-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-align: center;
}

.zoom-stage {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  align-items: center;
  background: var(--gradient-card-hero);
  border: 1px solid var(--border-medium);
  min-height: 380px;
  text-align: left;
}

.zoom-visual-box {
  display: flex;
  align-items: center;
  justify-content: center;
  transition: opacity 150ms ease;
}

.hero-svg {
  width: 100%;
  max-width: 380px;
  height: auto;
  filter: drop-shadow(0 4px 16px rgba(0,0,0,0.3));
}

.zoom-info-box {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.zoom-stage-title {
  font-size: 1.8rem;
  color: var(--text-primary);
}

.zoom-stage-sub {
  font-size: 0.95rem;
  color: var(--accent-olive-bright);
  font-weight: 600;
}

.zoom-stage-desc {
  color: var(--text-secondary);
  font-size: 0.96rem;
  line-height: 1.6;
}

.zoom-actions {
  display: flex;
  gap: 12px;
  margin-top: 12px;
  flex-wrap: wrap;
}

/* ==========================================================================
   1. Atom Explorer Section
   ========================================================================== */
.atom-explorer-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 28px;
  align-items: start;
}

.visual-stage-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 24px;
}

.visual-canvas-header {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  flex-wrap: wrap;
  gap: 10px;
}

.color-legend {
  display: flex;
  align-items: center;
  gap: 14px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.dot-proton { background-color: var(--accent-amber); box-shadow: 0 0 6px var(--accent-amber-glow); }
.dot-neutron { background-color: #64748b; }
.dot-electron { background-color: var(--accent-cyan-bright); box-shadow: 0 0 6px var(--accent-cyan-glow); }

.shell-occupancy-pill {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--accent-cyan-bright);
  background: var(--accent-cyan-soft);
  border: 1px solid var(--accent-cyan-glow);
  padding: 4px 10px;
  border-radius: var(--radius-full);
}

.canvas-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  padding: 6px;
}

#atom-canvas {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
}

.presets-bar {
  width: 100%;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 1px solid var(--border-subtle);
}

.presets-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  display: block;
  margin-bottom: 8px;
}

.preset-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.preset-chip {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 4px 10px;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.preset-chip:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-medium);
}

.preset-chip.active {
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  border-color: var(--accent-olive);
  box-shadow: 0 0 8px var(--accent-olive-glow);
}

/* Atom Controls & Identity */
.controls-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.identity-card {
  background: var(--gradient-card-identity);
  border: 1px solid var(--border-medium);
}

.identity-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
}

.element-box {
  width: 68px;
  height: 68px;
  border-radius: var(--radius-md);
  border: 2px solid var(--accent-olive-bright);
  background: var(--accent-olive-soft);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 0 0 14px var(--accent-olive-glow);
}

.element-box.unmatched {
  border-color: #64748b;
  background: rgba(100, 116, 139, 0.08);
}

.elem-z { font-size: 0.72rem; color: var(--text-muted); line-height: 1; }
.elem-sym { font-size: 1.6rem; font-weight: 800; color: var(--accent-olive-bright); line-height: 1.1; }
.elem-mass { font-size: 0.72rem; color: var(--text-secondary); line-height: 1; }

.identity-meta {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.identity-name {
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text-primary);
}

.identity-category-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: capitalize;
  color: var(--accent-olive-bright);
}

.identity-isotope {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.identity-isotope.highlight-isotope {
  color: #ef4444;
  font-weight: 600;
}

.metrics-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.metric-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 10px 14px;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.metric-label {
  font-size: 0.72rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.metric-val {
  font-size: 1.05rem;
  font-weight: 700;
  font-family: var(--font-mono);
}

.subatomic-controls-card {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.panel-subtitle {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 4px;
}

.counter-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 10px 14px;
}

.counter-meta {
  display: flex;
  align-items: center;
  gap: 12px;
}

.counter-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.counter-title {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
}

.counter-sub {
  font-size: 0.72rem;
  color: var(--text-muted);
}

.counter-btns {
  display: flex;
  align-items: center;
  gap: 8px;
}

.counter-val {
  font-size: 1.15rem;
  font-weight: 700;
  font-family: var(--font-mono);
  min-width: 28px;
  text-align: center;
}

.control-actions {
  display: flex;
  gap: 10px;
  margin-top: 6px;
}

/* ==========================================================================
   2. Element Explorer (Periodic Table)
   ========================================================================== */
.table-toolbar {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
  padding: 16px 20px;
}

.search-box {
  position: relative;
  display: flex;
  align-items: center;
  background: var(--bg-surface);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 4px 12px;
}

.search-icon {
  color: var(--text-muted);
  margin-right: 8px;
}

.search-box input {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.92rem;
  padding: 8px 0;
  outline: none;
}

.search-box input::placeholder {
  color: var(--text-muted);
}

.category-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.cat-pill {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.75rem;
  font-weight: 500;
  padding: 5px 10px;
  border-radius: var(--radius-full);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition-fast);
}

.cat-pill:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-medium);
}

.cat-pill.active {
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  border-color: var(--accent-olive);
  font-weight: 600;
}

.cat-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
}

.ptable-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 24px;
  align-items: start;
}

.ptable-grid-container {
  overflow-x: auto;
  padding: 16px;
}

.ptable-grid {
  display: grid;
  grid-template-columns: repeat(18, minmax(50px, 1fr));
  grid-template-rows: repeat(7, 56px);
  gap: 4px;
  min-width: 960px;
}

.ptable-cell {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: 4px;
  padding: 4px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-family: inherit;
  color: var(--text-primary);
  position: relative;
  transition: all var(--transition-fast);
}

.ptable-cell::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background-color: var(--cell-color, #94a3b8);
  border-radius: 4px 4px 0 0;
}

.ptable-cell:hover {
  transform: translateY(-2px) scale(1.04);
  z-index: 10;
  box-shadow: var(--shadow-md);
  border-color: var(--cell-color, var(--accent-olive-bright));
}

.ptable-cell.selected {
  border: 2px solid var(--accent-olive-bright);
  background: var(--accent-olive-soft);
  box-shadow: 0 0 12px var(--accent-olive-glow);
}

.ptable-cell.dimmed {
  opacity: 0.18;
}

.cell-num { font-size: 0.6rem; color: var(--text-muted); position: absolute; top: 3px; left: 4px; }
.cell-sym { font-size: 1.1rem; font-weight: 800; line-height: 1; margin-top: 4px; color: var(--text-primary); }
.cell-name { font-size: 0.55rem; color: var(--text-secondary); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 100%; }
.cell-mass { font-size: 0.52rem; color: var(--text-muted); }

.ptable-fblock {
  display: grid;
  grid-template-columns: repeat(15, minmax(50px, 1fr));
  gap: 4px;
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px dashed var(--border-subtle);
  min-width: 960px;
}

.element-inspector-card {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.inspector-header {
  display: flex;
  align-items: center;
  gap: 14px;
  padding-left: 10px;
  border-left: 4px solid var(--accent-olive);
}

.inspector-badge-box {
  width: 60px;
  height: 60px;
  border-radius: var(--radius-md);
  border: 2px solid var(--accent-olive-bright);
  background: var(--bg-surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 0 0 10px var(--accent-olive-glow);
}

.ib-num { font-size: 0.68rem; color: var(--text-muted); }
.ib-sym { font-size: 1.45rem; font-weight: 800; line-height: 1; color: var(--accent-olive-bright); }
.ib-mass { font-size: 0.65rem; color: var(--text-secondary); }

.inspector-title-meta {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.inspector-name {
  font-size: 1.35rem;
  font-weight: 700;
}

.inspector-cat {
  font-size: 0.72rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  display: inline-block;
  width: fit-content;
}

.inspector-facts-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}

.if-item {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 8px 10px;
  display: flex;
  flex-direction: column;
}

.if-label { font-size: 0.68rem; color: var(--text-muted); }
.if-val { font-size: 0.88rem; font-weight: 600; font-family: var(--font-mono); color: var(--text-primary); }

.inspector-fact-box {
  background: var(--accent-olive-subtle);
  border: 1px solid var(--accent-olive-glow);
  border-radius: var(--radius-md);
  padding: 12px;
}

.fact-box-title {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent-olive-bright);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 6px;
}

.fact-box-content {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

/* ==========================================================================
   3. Molecule Explorer Section
   ========================================================================== */
.molecule-tabs-bar {
  display: flex;
  gap: 8px;
  margin-bottom: 24px;
  padding: 12px;
  overflow-x: auto;
}

.mol-tab-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 8px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  cursor: pointer;
  color: var(--text-secondary);
  font-family: inherit;
  flex-shrink: 0;
  transition: all var(--transition-fast);
}

.mol-tab-btn:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-medium);
}

.mol-tab-btn.active {
  background: var(--accent-olive-soft);
  border-color: var(--accent-olive);
  color: var(--accent-olive-bright);
  box-shadow: 0 0 10px var(--accent-olive-glow);
}

.mol-tab-formula {
  font-size: 1.05rem;
  font-weight: 800;
}

.mol-tab-name {
  font-size: 0.72rem;
  opacity: 0.85;
}

.molecule-stage-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 24px;
  align-items: start;
}

.molecule-canvas-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 20px;
}

.canvas-header-bar {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  flex-wrap: wrap;
  gap: 8px;
}

.canvas-title-group {
  display: flex;
  align-items: center;
  gap: 10px;
}

.canvas-live-badge {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--accent-olive-bright);
  display: flex;
  align-items: center;
  gap: 6px;
}

.canvas-tip {
  font-size: 0.72rem;
  color: var(--text-muted);
}

.mol-canvas-container {
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: grab;
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  padding: 8px;
  width: 100%;
}

.mol-canvas-container:active {
  cursor: grabbing;
}

#molecule-3d-canvas {
  max-width: 100%;
  height: auto;
}

.mol-legend-footer {
  width: 100%;
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--border-subtle);
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.legend-chip {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  color: var(--text-secondary);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.legend-total {
  color: var(--accent-olive-bright);
  border-color: var(--accent-olive-glow);
  font-weight: 600;
}

.molecule-info-card {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.mol-info-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
}

.mol-formula-badge {
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--accent-olive-bright);
  line-height: 1.1;
}

.mol-title {
  font-size: 1.3rem;
  color: var(--text-primary);
}

.mol-badge-stack {
  display: flex;
  flex-direction: column;
  gap: 6px;
  align-items: flex-end;
}

.mol-breakdown-box {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 12px 14px;
}

.breakdown-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  color: var(--text-muted);
  letter-spacing: 0.04em;
  margin-bottom: 8px;
}

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

.b-chip {
  background: var(--bg-card);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-sm);
  padding: 6px 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.b-sym {
  font-weight: 800;
  font-size: 0.95rem;
}

.b-text {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

.box-section-title {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.mol-desc-text, .mol-relevance-text {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.mol-explanation-box {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 12px;
}

.mol-relevance-box {
  background: var(--accent-olive-subtle);
  border: 1px solid var(--accent-olive-glow);
  border-radius: var(--radius-md);
  padding: 12px;
}

/* ==========================================================================
   4. Quick Challenges Section
   ========================================================================== */
.challenges-wrapper {
  max-width: 860px;
  margin: 0 auto;
  padding: 30px;
}

.challenges-header {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-subtle);
}

.score-display {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.score-label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.score-val {
  font-size: 1.15rem;
  font-weight: 800;
  font-family: var(--font-mono);
}

.question-navigator {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.q-pill {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-family: inherit;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.q-pill:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
}

.q-pill.current {
  border-color: var(--accent-olive-bright);
  color: var(--accent-olive-bright);
  box-shadow: 0 0 8px var(--accent-olive-glow);
}

.q-pill.correct {
  background: rgba(34, 197, 94, 0.18);
  border-color: #22c55e;
  color: #22c55e;
}

.q-pill.incorrect {
  background: rgba(239, 68, 68, 0.18);
  border-color: #ef4444;
  color: #ef4444;
}

.challenge-stage {
  min-height: 280px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.q-meta-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.q-type-badge {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.q-text {
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 20px;
  color: var(--text-primary);
}

.options-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 10px;
  margin-bottom: 20px;
}

.option-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  display: flex;
  align-items: center;
  gap: 14px;
  cursor: pointer;
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.92rem;
  text-align: left;
  transition: all var(--transition-fast);
}

.option-btn:hover:not(.locked) {
  background: var(--bg-card-hover);
  border-color: var(--accent-olive);
  transform: translateX(4px);
}

.opt-letter {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.8rem;
  flex-shrink: 0;
}

.opt-text {
  flex: 1;
}

.option-btn.opt-correct {
  background: rgba(34, 197, 94, 0.15);
  border-color: #22c55e;
  color: var(--text-primary);
}

.option-btn.opt-correct .opt-letter {
  background: #22c55e;
  color: #ffffff;
}

.option-btn.opt-incorrect {
  background: rgba(239, 68, 68, 0.15);
  border-color: #ef4444;
  color: var(--text-primary);
}

.option-btn.opt-incorrect .opt-letter {
  background: #ef4444;
  color: #ffffff;
}

.feedback-banner {
  border-radius: var(--radius-md);
  padding: 14px 18px;
  margin-top: 10px;
  animation: fadeIn 300ms ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.fb-correct {
  background: rgba(34, 197, 94, 0.12);
  border: 1px solid rgba(34, 197, 94, 0.3);
}

.fb-incorrect {
  background: rgba(239, 68, 68, 0.12);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

.fb-header {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  margin-bottom: 4px;
}

.fb-correct .fb-header { color: #22c55e; }
.fb-incorrect .fb-header { color: #ef4444; }

.fb-explanation {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.challenge-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid var(--border-subtle);
}

.q-counter-label {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Summary Card */
.summary-container {
  text-align: center;
  padding: 20px;
}

.summary-badge-pill {
  display: inline-block;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: var(--accent-olive-soft);
  color: var(--accent-olive-bright);
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: 16px;
}

.summary-score-title {
  font-size: 2rem;
  margin-bottom: 8px;
}

.summary-pct-ring {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--accent-olive-bright);
  font-family: var(--font-mono);
  margin-bottom: 12px;
}

.summary-subtext {
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.summary-actions {
  display: flex;
  justify-content: center;
  gap: 12px;
}

/* ==========================================================================
   5. Contributor Library Section
   ========================================================================== */
.library-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  padding: 14px 20px;
  flex-wrap: wrap;
  gap: 12px;
}

.sci-count-pill {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

.sci-layout-grid {
  display: grid;
  grid-template-columns: 1fr 1.1fr;
  gap: 24px;
  align-items: start;
}

.sci-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 12px;
  max-height: 720px;
  overflow-y: auto;
  padding-right: 6px;
}

.sci-exhibit-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 14px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  cursor: pointer;
  text-align: left;
  font-family: inherit;
  color: var(--text-primary);
  transition: all var(--transition-fast);
}

.sci-exhibit-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  transform: translateY(-2px);
}

.sci-exhibit-card.selected {
  background: var(--accent-olive-soft);
  border-color: var(--accent-olive);
  box-shadow: 0 0 12px var(--accent-olive-glow);
}

.sci-card-header {
  display: flex;
  align-items: center;
  gap: 12px;
}

.sci-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gradient-avatar);
  border: 1px solid var(--border-medium);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.sci-initials {
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--accent-olive-bright);
}

.sci-card-name {
  font-size: 0.98rem;
  font-weight: 700;
}

.sci-card-lifespan {
  font-size: 0.72rem;
  color: var(--text-muted);
}

.sci-card-tagline {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.4;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.sci-tag-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 4px;
}

.sci-mini-tag {
  font-size: 0.68rem;
  background: var(--bg-surface);
  color: var(--text-muted);
  padding: 2px 6px;
  border-radius: 4px;
  border: 1px solid var(--border-subtle);
}

/* 5-Field Dossier Card */
.sci-dossier-card {
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.dossier-hero {
  display: flex;
  align-items: center;
  gap: 18px;
}

.dossier-avatar-large {
  width: 68px;
  height: 68px;
  border-radius: 50%;
  background: var(--gradient-avatar-large);
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 0 16px var(--accent-olive-glow);
  flex-shrink: 0;
}

.avatar-text {
  font-size: 1.5rem;
  font-weight: 800;
  color: #ffffff;
}

.dossier-era-badge {
  font-size: 0.75rem;
  color: var(--accent-olive-bright);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.dossier-name {
  font-size: 1.6rem;
  font-weight: 800;
}

.dossier-dates {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.dossier-tagline-quote {
  font-style: italic;
  color: var(--accent-amber-bright);
  font-size: 0.95rem;
  padding: 8px 14px;
  background: var(--accent-amber-soft);
  border-left: 3px solid var(--accent-amber);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.dossier-sections-stack {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.dossier-block {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 14px;
}

.dossier-block.highlight-modern {
  background: var(--accent-olive-subtle);
  border-color: var(--accent-olive-glow);
}

.dossier-block-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}

.block-num {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--accent-olive-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--accent-olive-bright);
}

.block-title {
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-primary);
}

.dossier-block-text {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Footer */
.museum-footer {
  background: var(--bg-surface);
  border-top: 1px solid var(--border-subtle);
  padding: 40px 24px;
  text-align: center;
  margin-top: 40px;
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.footer-content {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: center;
}

.footer-logo {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-primary);
}

.footer-text {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Scrollbars */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-core);
}

::-webkit-scrollbar-thumb {
  background: var(--border-medium);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--accent-olive);
}

/* Responsive Media Queries */
@media (max-width: 1080px) {
  .atom-explorer-grid,
  .molecule-stage-grid,
  .ptable-layout,
  .sci-layout-grid,
  .zoom-stage {
    grid-template-columns: 1fr;
  }

  .hero-title {
    font-size: 2.5rem;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border-subtle);
    flex-direction: column;
    padding: 16px;
    gap: 8px;
  }

  .nav-links.open {
    display: flex;
  }

  .mobile-menu-btn {
    display: block;
  }

  .zoom-track {
    grid-template-columns: repeat(2, 1fr);
  }

  .zoom-track .zoom-step-node:last-child {
    grid-column: span 2;
  }

  .section-title {
    font-size: 1.8rem;
  }
}