:root {
  --bg-primary: #070a0e;
  --bg-surface: #0e141c;
  --bg-surface-elevated: #151e2a;
  --bg-subtle: #1c2837;
  --border-subtle: #243346;
  --border-strong: #384d66;
  
  --text-primary: #f0f4f8;
  --text-secondary: #9db2c7;
  --text-muted: #62778d;
  
  --accent-voltage: #38bdf8;
  --accent-voltage-glow: rgba(56, 189, 248, 0.15);
  --accent-na: #f59e0b;
  --accent-na-glow: rgba(245, 158, 11, 0.15);
  --accent-k: #a855f7;
  --accent-k-glow: rgba(168, 85, 247, 0.15);
  --accent-danger: #ef4444;
  --accent-success: #10b981;
  
  --font-serif: "Newsreader", Georgia, Cambria, "Times New Roman", serif;
  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;
  
  --shadow-card: 0 4px 20px -2px rgba(0, 0, 0, 0.5), 0 0 0 1px var(--border-subtle);
  --shadow-elevated: 0 12px 32px -4px rgba(0, 0, 0, 0.7), 0 0 0 1px var(--border-strong);
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-sans);
  line-height: 1.65;
  background: var(--bg-primary);
  color: var(--text-primary);
  overflow-x: hidden;
  min-height: 100vh;
}

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

/* Container & Layout */
.page-container {
  max-width: 920px;
  margin: 0 auto;
  padding: 0 24px;
}

@media (max-width: 640px) {
  .page-container {
    padding: 0 16px;
  }
}

/* Navigation Header */
.site-header {
  border-bottom: 1px solid var(--border-subtle);
  background: rgba(7, 10, 14, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 50;
}

.site-header .inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 64px;
}

.site-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 500;
  transition: opacity 0.15s ease;
}

.site-brand:hover {
  opacity: 0.85;
}

.site-brand-icon {
  width: 22px;
  height: 22px;
  display: block;
}

.site-nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  padding: 3px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 600;
}

.lang-link {
  padding: 4px 10px;
  border-radius: var(--radius-full);
  text-decoration: none;
  color: var(--text-muted);
  transition: all 0.15s ease;
}

.lang-link:hover {
  color: var(--text-primary);
}

.lang-link.active {
  background: var(--bg-subtle);
  color: var(--accent-voltage);
}

/* Hero Section */
.hero {
  padding: 64px 0 40px;
}

@media (max-width: 640px) {
  .hero {
    padding: 40px 0 24px;
  }
}

.kicker {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-voltage);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.kicker::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-voltage);
  box-shadow: 0 0 10px var(--accent-voltage);
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 5vw, 3.8rem);
  font-weight: 600;
  line-height: 1.15;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin: 0 0 20px;
}

.hero-deck {
  font-size: clamp(1.1rem, 2.2vw, 1.35rem);
  font-weight: 400;
  line-height: 1.6;
  color: var(--text-secondary);
  margin: 0 0 28px;
  max-width: 780px;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text-muted);
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border-subtle);
}

.meta-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
}

/* Callout Stat Box */
.stat-banner {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin: 32px 0 48px;
}

.stat-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 20px;
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--stat-color, var(--accent-voltage));
}

.stat-label {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.stat-value {
  font-family: var(--font-mono);
  font-size: 1.85rem;
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.stat-subtext {
  font-size: 0.86rem;
  color: var(--text-secondary);
  line-height: 1.45;
  margin: 0;
}

/* Article Prose */
.prose {
  font-size: 1.06rem;
  line-height: 1.75;
  color: var(--text-primary);
}

.prose p {
  margin: 0 0 1.5em;
}

.prose h2 {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.25;
  color: var(--text-primary);
  margin: 2.2em 0 0.8em;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-subtle);
}

.prose h3 {
  font-family: var(--font-sans);
  font-size: 1.25rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--text-primary);
  margin: 1.8em 0 0.6em;
}

.prose strong {
  color: #fff;
  font-weight: 600;
}

.prose em {
  font-family: var(--font-serif);
  font-style: italic;
}

.prose a {
  color: var(--accent-voltage);
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: opacity 0.15s ease;
}

.prose a:hover {
  opacity: 0.8;
}

/* Interactive Chamber Application */
.interactive-section {
  margin: 48px 0;
  background: var(--bg-surface);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-elevated);
  overflow: hidden;
}

.chamber-header {
  padding: 20px 24px;
  background: var(--bg-surface-elevated);
  border-bottom: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

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

.chamber-icon {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--accent-voltage);
  box-shadow: 0 0 12px var(--accent-voltage);
  animation: pulse-glow 2.5s infinite;
}

@keyframes pulse-glow {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(0.85); }
}

.chamber-heading {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--text-primary);
  margin: 0;
}

.chamber-status-badge {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  padding: 3px 8px;
  border-radius: var(--radius-full);
  background: rgba(56, 189, 248, 0.12);
  border: 1px solid var(--accent-voltage);
  color: var(--accent-voltage);
}

.chamber-body {
  padding: 24px;
}

@media (max-width: 640px) {
  .chamber-body {
    padding: 16px;
  }
}

/* Preset Buttons */
.preset-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 24px;
}

.preset-btn {
  background: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

.preset-btn:hover {
  background: var(--bg-surface-elevated);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.preset-btn.active {
  background: rgba(56, 189, 248, 0.15);
  border-color: var(--accent-voltage);
  color: var(--accent-voltage);
  font-weight: 600;
}

/* Simulator Grid */
.simulator-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

@media (max-width: 800px) {
  .simulator-layout {
    grid-template-columns: 1fr;
  }
}

/* Controls Column */
.control-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.control-group {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 16px;
}

.control-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 10px;
}

.control-label {
  font-size: 0.88rem;
  font-weight: 500;
  color: var(--text-primary);
}

.control-val-badge {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--accent-voltage);
}

.range-slider {
  width: 100%;
  height: 6px;
  border-radius: var(--radius-full);
  background: var(--bg-subtle);
  outline: none;
  -webkit-appearance: none;
  cursor: pointer;
}

.range-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--accent-voltage);
  box-shadow: 0 0 8px var(--accent-voltage);
  cursor: pointer;
  transition: transform 0.1s ease;
}

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

.range-slider::-moz-range-thumb {
  width: 18px;
  height: 18px;
  border: none;
  border-radius: 50%;
  background: var(--accent-voltage);
  box-shadow: 0 0 8px var(--accent-voltage);
  cursor: pointer;
}

.slider-ticks {
  display: flex;
  justify-content: space-between;
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
}

/* Canvas Viewport */
.canvas-wrapper {
  background: #040608;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.canvas-viewport {
  width: 100%;
  height: 280px;
  display: block;
}

.canvas-legend {
  padding: 10px 14px;
  background: rgba(14, 20, 28, 0.9);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: space-around;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-secondary);
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

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

.legend-dot.na { background: var(--accent-na); box-shadow: 0 0 6px var(--accent-na); }
.legend-dot.k { background: var(--accent-k); box-shadow: 0 0 6px var(--accent-k); }
.legend-dot.field { background: var(--accent-voltage); }

/* Live Metrics Readout */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px;
  margin-top: 20px;
}

.metric-box {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 14px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.metric-title {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.metric-value-live {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
}

.metric-detail {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 4px;
}

/* Whole Body Calculator Box */
.body-calc-section {
  margin-top: 24px;
  padding-top: 24px;
  border-top: 1px solid var(--border-subtle);
}

.body-calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin-top: 16px;
}

.body-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 16px;
}

.body-card-val {
  font-family: var(--font-mono);
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--accent-voltage);
  margin-bottom: 4px;
}

/* Comparison Gauge Bar */
.gauge-track {
  width: 100%;
  height: 10px;
  background: var(--bg-subtle);
  border-radius: var(--radius-full);
  margin: 12px 0 6px;
  position: relative;
  overflow: hidden;
}

.gauge-fill {
  height: 100%;
  background: linear-gradient(90deg, #38bdf8 0%, #f59e0b 60%, #ef4444 100%);
  border-radius: var(--radius-full);
  transition: width 0.2s ease;
}

.gauge-marker {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 2px;
  background: #fff;
  z-index: 2;
}

/* Method & References Note */
.method-note {
  margin: 48px 0;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 24px;
}

.method-note h3 {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-primary);
  margin: 0 0 16px;
}

.reference-list {
  margin: 16px 0 0;
  padding-left: 20px;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.reference-list li {
  margin-bottom: 10px;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border-subtle);
  padding: 40px 0 60px;
  margin-top: 80px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-muted);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-links {
  display: flex;
  gap: 16px;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.15s ease;
}

.footer-links a:hover {
  color: var(--accent-voltage);
}

/* Back to Top Button */
.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-strong);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: var(--shadow-card);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all 0.2s ease;
  z-index: 40;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--bg-subtle);
  border-color: var(--accent-voltage);
  color: var(--accent-voltage);
}

/* Reduced Motion Mode */
@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;
  }
}