:root {
  --bg-primary: #141210;
  --bg-surface: #1d1916;
  --bg-surface-elevated: #27221e;
  --bg-surface-border: #38312b;
  --bg-surface-hover: #322b24;
  
  --text-main: #f5ede4;
  --text-muted: #a6998d;
  --text-subtle: #73685e;
  
  --accent-tactile: #e06c28;
  --accent-tactile-light: #f58e4e;
  --accent-tactile-glow: rgba(224, 108, 40, 0.2);
  --accent-success: #22c55e;
  --accent-warning: #eab308;
  --accent-fused: #ef4444;
  --accent-cyan: #38bdf8;
  
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  
  --max-width: 1040px;
  --border-radius-sm: 6px;
  --border-radius-md: 10px;
  --border-radius-lg: 16px;
  --transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-image: 
    radial-gradient(circle at 50% 0%, rgba(224, 108, 40, 0.08) 0%, transparent 60%),
    radial-gradient(circle at 100% 40%, rgba(56, 189, 248, 0.03) 0%, transparent 40%);
  background-attachment: fixed;
}

/* Accessibility: FM-001 prevention */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Header */
.site-header {
  border-bottom: 1px solid var(--bg-surface-border);
  background: rgba(20, 18, 16, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.85rem 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--text-main);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}

.brand-badge {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.2rem 0.45rem;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-sm);
  color: var(--accent-tactile-light);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.lang-switch {
  display: inline-flex;
  background: var(--bg-surface);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-sm);
  padding: 0.2rem;
  font-size: 0.8rem;
  font-weight: 600;
}

.lang-btn {
  padding: 0.25rem 0.55rem;
  border-radius: 4px;
  text-decoration: none;
  color: var(--text-muted);
  transition: var(--transition);
}

.lang-btn.active {
  background: var(--accent-tactile);
  color: #ffffff;
}

.lang-btn:hover:not(.active) {
  color: var(--text-main);
}

/* Main Layout */
.main-wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem 1.25rem 5rem;
  flex: 1;
  width: 100%;
}

/* Typography & Badges */
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-tactile-light);
  margin-bottom: 1rem;
}

.hero-title {
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.03em;
  color: #ffffff;
  margin-bottom: 1.25rem;
}

.hero-lead {
  font-size: clamp(1.1rem, 2.2vw, 1.28rem);
  line-height: 1.55;
  color: var(--text-muted);
  max-width: 820px;
  margin-bottom: 2.5rem;
}

/* Stat Grid */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.25rem;
  margin-bottom: 3.5rem;
}

.stat-card {
  background: var(--bg-surface);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.4rem;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-card::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-tactile);
  opacity: 0.4;
}

.stat-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent-tactile);
  box-shadow: 0 8px 24px var(--accent-tactile-glow);
}

.stat-value {
  font-family: var(--font-mono);
  font-size: 2.2rem;
  font-weight: 700;
  color: #ffffff;
  line-height: 1.1;
  margin-bottom: 0.35rem;
}

.stat-value span {
  font-size: 1.1rem;
  color: var(--accent-tactile-light);
  margin-left: 0.2rem;
}

.stat-label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

.stat-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Main Interactive Apparatus */
.apparatus-section {
  background: var(--bg-surface);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-lg);
  padding: 2rem;
  margin-bottom: 3.5rem;
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.4);
}

.apparatus-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.75rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--bg-surface-border);
}

.apparatus-title {
  font-size: 1.4rem;
  font-weight: 700;
  color: #ffffff;
  letter-spacing: -0.01em;
}

.apparatus-subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* Preset Selectors */
.region-presets {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1.75rem;
}

.preset-btn {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-sm);
  color: var(--text-muted);
  padding: 0.55rem 0.9rem;
  font-size: 0.84rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 0.45rem;
}

.preset-btn:hover {
  color: var(--text-main);
  background: var(--bg-surface-hover);
  border-color: var(--accent-tactile);
}

.preset-btn.active {
  background: var(--accent-tactile);
  border-color: var(--accent-tactile);
  color: #ffffff;
  box-shadow: 0 2px 10px var(--accent-tactile-glow);
}

.preset-tag {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  opacity: 0.85;
  background: rgba(0, 0, 0, 0.25);
  padding: 0.1rem 0.35rem;
  border-radius: 3px;
}

/* Interactive Canvas & Caliper */
.caliper-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.75rem;
  margin-bottom: 2rem;
}

@media (max-width: 820px) {
  .caliper-container {
    grid-template-columns: 1fr;
  }
}

.canvas-panel {
  background: #110e0c;
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
}

.canvas-label {
  align-self: flex-start;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

canvas {
  width: 100%;
  height: 240px;
  display: block;
}

/* Controls Column */
.controls-panel {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.control-group {
  margin-bottom: 1.5rem;
}

.control-label-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 0.5rem;
}

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

.control-value {
  font-family: var(--font-mono);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent-tactile-light);
}

.custom-range {
  width: 100%;
  height: 8px;
  -webkit-appearance: none;
  appearance: none;
  background: var(--bg-surface-elevated);
  border-radius: 4px;
  outline: none;
  margin: 0.75rem 0;
}

.custom-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent-tactile);
  border: 2px solid #ffffff;
  cursor: pointer;
  box-shadow: 0 0 10px var(--accent-tactile-glow);
  transition: var(--transition);
}

.custom-range::-webkit-slider-thumb:hover {
  transform: scale(1.15);
}

.custom-range::-moz-range-thumb {
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: var(--accent-tactile);
  border: 2px solid #ffffff;
  cursor: pointer;
  box-shadow: 0 0 10px var(--accent-tactile-glow);
}

/* Verdict Box */
.verdict-box {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.25rem;
  transition: var(--transition);
}

.verdict-icon {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  flex-shrink: 0;
}

.verdict-icon.distinct {
  background: rgba(34, 197, 94, 0.15);
  color: var(--accent-success);
  border: 1px solid rgba(34, 197, 94, 0.3);
}

.verdict-icon.fused {
  background: rgba(239, 68, 68, 0.15);
  color: var(--accent-fused);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

.verdict-text-title {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.2rem;
}

.verdict-text-title.distinct {
  color: var(--accent-success);
}

.verdict-text-title.fused {
  color: var(--accent-fused);
}

.verdict-text-desc {
  font-size: 0.84rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Live Physical Caliper Ruler calibration */
.physical-test-box {
  background: var(--bg-surface-elevated);
  border: 1px dashed var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.25rem;
  margin-top: 1.5rem;
}

.physical-ruler-canvas {
  width: 100%;
  height: 60px;
  background: #0f0d0b;
  border-radius: 4px;
  margin: 0.75rem 0;
}

.physical-instructions {
  font-size: 0.84rem;
  color: var(--text-muted);
  line-height: 1.5;
}

/* Table of Anatomical Data */
.data-table-container {
  width: 100%;
  overflow-x: auto;
  margin: 2.5rem 0;
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  background: var(--bg-surface);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.9rem;
}

.data-table th {
  background: var(--bg-surface-elevated);
  padding: 0.9rem 1.1rem;
  font-weight: 700;
  color: #ffffff;
  border-bottom: 1px solid var(--bg-surface-border);
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.data-table td {
  padding: 0.85rem 1.1rem;
  border-bottom: 1px solid rgba(56, 49, 43, 0.4);
  color: var(--text-muted);
}

.data-table tr:hover td {
  background: var(--bg-surface-hover);
  color: var(--text-main);
}

.data-table td.mono {
  font-family: var(--font-mono);
  font-weight: 600;
  color: #ffffff;
}

.data-table td.highlight {
  color: var(--accent-tactile-light);
  font-family: var(--font-mono);
  font-weight: 700;
}

/* Deep Explainer Article Typography */
.article-content {
  margin: 3.5rem 0;
  font-size: 1.05rem;
  line-height: 1.75;
  color: #e5ded5;
}

.article-content h2 {
  font-size: 1.75rem;
  font-weight: 800;
  color: #ffffff;
  margin: 2.75rem 0 1rem;
  letter-spacing: -0.02em;
}

.article-content h3 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent-tactile-light);
  margin: 2rem 0 0.75rem;
}

.article-content p {
  margin-bottom: 1.4rem;
}

.article-content strong {
  color: #ffffff;
  font-weight: 600;
}

.article-content em {
  font-style: italic;
  color: #f7dfcb;
}

.article-content ul, .article-content ol {
  margin: 1rem 0 1.5rem 1.5rem;
}

.article-content li {
  margin-bottom: 0.5rem;
}

.callout-card {
  background: var(--bg-surface);
  border-left: 3px solid var(--accent-tactile);
  border-radius: 0 var(--border-radius-md) var(--border-radius-md) 0;
  padding: 1.25rem 1.5rem;
  margin: 2rem 0;
  font-size: 0.95rem;
  color: var(--text-muted);
}

.callout-card strong {
  color: var(--accent-tactile-light);
}

/* Homunculus visual grid comparison */
.homunculus-card {
  background: var(--bg-surface);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.75rem;
  margin: 2.5rem 0;
}

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

.homunculus-item {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-sm);
  padding: 1.2rem;
}

.homunculus-item-title {
  font-size: 0.92rem;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 0.75rem;
  display: flex;
  justify-content: space-between;
}

.bar-track {
  width: 100%;
  height: 8px;
  background: rgba(0, 0, 0, 0.4);
  border-radius: 4px;
  overflow: hidden;
  margin: 0.5rem 0 0.25rem;
}

.bar-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.6s ease;
}

.bar-fill.skin {
  background: var(--text-muted);
}

.bar-fill.cortex {
  background: var(--accent-tactile);
}

/* Methods and Sources */
.methods-box {
  background: #110e0c;
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-md);
  padding: 1.5rem;
  margin-top: 3.5rem;
  font-size: 0.88rem;
  color: var(--text-subtle);
}

.methods-box h4 {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.methods-box p {
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.methods-box a {
  color: var(--accent-tactile-light);
  text-decoration: none;
}

.methods-box a:hover {
  text-decoration: underline;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--bg-surface-border);
  padding: 2.5rem 1.25rem;
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-subtle);
  background: #0f0d0b;
}

.site-footer a {
  color: var(--text-muted);
  text-decoration: none;
  transition: var(--transition);
}

.site-footer a:hover {
  color: var(--accent-tactile-light);
}

.back-to-top-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1rem;
  padding: 0.4rem 0.8rem;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--bg-surface-border);
  border-radius: var(--border-radius-sm);
  color: var(--text-muted);
  font-size: 0.8rem;
  cursor: pointer;
  transition: var(--transition);
}

.back-to-top-btn:hover {
  background: var(--bg-surface-hover);
  color: #ffffff;
  border-color: var(--accent-tactile);
}

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}