:root {
  --bg: #0d1117;
  --bg-surface: #161b22;
  --bg-elevated: #21262d;
  --bg-input: #0b0f14;
  --border: #30363d;
  --border-focus: #58a6ff;
  --border-light: rgba(255, 255, 255, 0.08);

  --ink: #f0f6fc;
  --ink-soft: #8b949e;
  --ink-muted: #6e7681;
  --ink-faint: #484f58;

  --accent-f1: #f0883e;       /* Pharynx / Jaw open / Low resonance / Warm amber */
  --accent-f1-glow: rgba(240, 136, 62, 0.25);
  --accent-f2: #38bdf8;       /* Oral cavity / Tongue front / High resonance / Bright Cyan */
  --accent-f2-glow: rgba(56, 189, 248, 0.25);
  --accent-center: #a78bfa;   /* Central vowels (ă, î/â) / Violet */
  --accent-chord: #4ade80;    /* Combined resonance / Green */

  --font-serif: "Fraunces", "Playfair Display", Georgia, serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "JetBrains Mono", "SF Mono", "Spline Sans Mono", Menlo, Consolas, monospace;

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

  --shadow-subtle: 0 4px 20px rgba(0, 0, 0, 0.35);
  --shadow-glow: 0 0 25px rgba(56, 189, 248, 0.15);
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Accessibility utility */
.visually-hidden {
  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;
}

.visually-hidden:focus {
  position: fixed !important;
  top: 1rem;
  left: 1rem;
  width: auto !important;
  height: auto !important;
  padding: 0.75rem 1.25rem !important;
  background: var(--accent-f2);
  color: #000;
  font-weight: 700;
  z-index: 1000;
  border-radius: var(--radius-sm);
  clip: auto !important;
}

/* Top bar navigation */
.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.25rem 2rem;
  max-width: 1200px;
  margin: 0 auto;
  width: 100%;
  border-bottom: 1px solid var(--border-light);
}

.brand {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: -0.01em;
}

.brand:hover {
  color: var(--accent-f2);
}

.langsw {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--ink-soft);
}

.langsw a {
  color: var(--ink-soft);
  text-decoration: none;
  padding: 0.2rem 0.4rem;
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
}

.langsw a:hover {
  color: var(--ink);
}

.langsw a[aria-current="page"] {
  color: var(--ink);
  font-weight: 700;
  background: var(--bg-surface);
  border: 1px solid var(--border);
}

/* Layout shells */
.shell {
  max-width: 820px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.shell-wide {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Hero Section */
.hero {
  padding: 4.5rem 0 3rem;
  text-align: left;
}

.kicker {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-f2);
  margin-bottom: 1rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.kicker::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-f2);
  box-shadow: 0 0 10px var(--accent-f2);
}

h1 {
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 5.5vw, 3.8rem);
  font-weight: 600;
  line-height: 1.12;
  letter-spacing: -0.03em;
  color: var(--ink);
  margin-bottom: 1.5rem;
}

.standfirst {
  font-size: 1.25rem;
  line-height: 1.6;
  color: var(--ink-soft);
  margin-bottom: 2.5rem;
  font-weight: 400;
}

/* Ledger Metrics Grid */
.ledgerline {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.25rem;
  padding: 1.75rem;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-subtle);
  margin-bottom: 3.5rem;
}

.ledger-item {
  display: flex;
  flex-direction: column;
}

.ledger-item .n {
  font-family: var(--font-mono);
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--ink);
  line-height: 1.2;
  margin-bottom: 0.35rem;
  display: flex;
  align-items: baseline;
  gap: 0.25rem;
}

.ledger-item .n.f1 { color: var(--accent-f1); }
.ledger-item .n.f2 { color: var(--accent-f2); }
.ledger-item .n.center { color: var(--accent-center); }
.ledger-item .n.chord { color: var(--accent-chord); }

.ledger-item .l {
  font-size: 0.88rem;
  color: var(--ink-soft);
  line-height: 1.4;
}

/* Prose Sections */
.prose {
  font-size: 1.1rem;
  line-height: 1.75;
  color: #c9d1d9;
}

.prose h2 {
  font-family: var(--font-serif);
  font-size: 1.95rem;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
  margin: 3.5rem 0 1.25rem;
  line-height: 1.25;
}

.prose h3 {
  font-family: var(--font-serif);
  font-size: 1.45rem;
  font-weight: 600;
  color: var(--ink);
  margin: 2.25rem 0 0.85rem;
}

.prose p {
  margin-bottom: 1.35rem;
}

.prose strong {
  color: var(--ink);
  font-weight: 600;
}

.prose em {
  font-style: italic;
  color: #e6edf3;
}

/* Interactive Laboratory Section */
.instrument-section {
  padding: 3.5rem 0 4.5rem;
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
  background: radial-gradient(circle at 50% 30%, rgba(56, 189, 248, 0.04), transparent 70%);
}

.instrument-card {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-subtle);
}

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

.instrument-title h3 {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 0.35rem;
}

.instrument-title p {
  font-size: 0.95rem;
  color: var(--ink-soft);
}

/* Controls & Toolbar */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.85rem;
}

.btn-group {
  display: inline-flex;
  background: var(--bg-elevated);
  padding: 0.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

.btn-toggle {
  background: transparent;
  border: none;
  color: var(--ink-soft);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  padding: 0.45rem 0.85rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-toggle:hover {
  color: var(--ink);
}

.btn-toggle[aria-pressed="true"] {
  background: var(--bg-surface);
  color: var(--ink);
  font-weight: 600;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
  border: 1px solid var(--border);
}

.btn-audio {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: var(--accent-f2);
  color: #0d1117;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  padding: 0.55rem 1.15rem;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-audio:hover {
  background: #7dd3fc;
  transform: translateY(-1px);
  box-shadow: 0 0 15px var(--accent-f2-glow);
}

.btn-audio.playing {
  background: #ef4444;
  color: #fff;
  animation: pulse-red 1.5s infinite;
}

@keyframes pulse-red {
  0% { box-shadow: 0 0 0 0 rgba(239, 68, 68, 0.4); }
  70% { box-shadow: 0 0 0 10px rgba(239, 68, 68, 0); }
  100% { box-shadow: 0 0 0 0 rgba(239, 68, 68, 0); }
}

/* Workspace Canvas & Resonator Grid */
.workspace-grid {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 2rem;
  align-items: start;
}

@media (max-width: 960px) {
  .workspace-grid {
    grid-template-columns: 1fr;
  }
}

.canvas-container {
  position: relative;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  touch-action: none;
  user-select: none;
}

canvas#vowelCanvas {
  display: block;
  width: 100%;
  height: 480px;
  cursor: crosshair;
}

.canvas-hint {
  position: absolute;
  bottom: 0.75rem;
  left: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--ink-muted);
  background: rgba(13, 17, 23, 0.85);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  backdrop-filter: blur(4px);
  pointer-events: none;
}

/* Sidebar Readouts & Vocal Tract Model */
.sidebar-readouts {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.readout-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
}

.readout-card h4 {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  margin-bottom: 0.75rem;
}

.readout-main-vowel {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.vowel-badge {
  font-family: var(--font-serif);
  font-size: 3rem;
  font-weight: 700;
  line-height: 1;
  color: var(--ink);
  background: var(--bg-surface);
  width: 72px;
  height: 72px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  border: 2px solid var(--accent-f2);
  box-shadow: var(--shadow-glow);
}

.vowel-info {
  flex: 1;
  margin-left: 1rem;
}

.vowel-word {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--ink);
}

.vowel-desc {
  font-size: 0.82rem;
  color: var(--ink-soft);
  line-height: 1.3;
}

.freq-bars {
  display: flex;
  flex-direction: column;
  gap: 0.85rem;
}

.freq-row {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.freq-label {
  display: flex;
  justify-content: space-between;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.freq-label .tag {
  color: var(--ink-soft);
}

.freq-label .val {
  font-weight: 700;
}

.freq-label .val.f1 { color: var(--accent-f1); }
.freq-label .val.f2 { color: var(--accent-f2); }

.bar-track {
  height: 8px;
  background: var(--bg-surface);
  border-radius: 4px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.bar-fill {
  height: 100%;
  border-radius: 4px;
  transition: width 0.08s ease;
}

.bar-fill.f1 { background: var(--accent-f1); }
.bar-fill.f2 { background: var(--accent-f2); }

/* Physical Mouth Geometry Diagram */
.mouth-resonator-box {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.mouth-svg-container {
  width: 100%;
  height: 140px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
}

.mouth-svg-container svg {
  width: 100%;
  height: 100%;
}

.mouth-legend {
  font-size: 0.78rem;
  color: var(--ink-soft);
  line-height: 1.4;
}

/* Word Player / Trajectory Tool */
.word-player-section {
  margin-top: 1.75rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

.word-player-header {
  margin-bottom: 1rem;
}

.word-player-header h4 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--ink);
  margin-bottom: 0.25rem;
}

.word-player-header p {
  font-size: 0.88rem;
  color: var(--ink-soft);
}

.word-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.preset-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.btn-chip {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-chip:hover {
  border-color: var(--accent-f2);
  color: var(--accent-f2);
  background: rgba(56, 189, 248, 0.08);
}

.btn-chip.active {
  background: var(--accent-f2);
  color: #0d1117;
  font-weight: 600;
  border-color: var(--accent-f2);
}

.text-input-wrap {
  display: flex;
  gap: 0.5rem;
  width: 100%;
}

.text-input {
  flex: 1;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 0.6rem 1rem;
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  transition: border-color 0.2s ease;
}

.text-input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.15);
}

.btn-trace {
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius-md);
  cursor: pointer;
  font-weight: 600;
  transition: all 0.2s ease;
}

.btn-trace:hover {
  background: var(--accent-f2);
  color: #0d1117;
}

.trajectory-stats {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--ink-soft);
  margin-top: 0.75rem;
}

.trajectory-stats span b {
  color: var(--accent-chord);
}

/* Tooltip Component */
.stat-item-tooltip {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  position: relative;
}

.tooltip-container {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.tooltip-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  color: var(--accent-f2);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  cursor: pointer;
  padding: 0;
  line-height: 1;
  transition: all 0.2s ease;
}

.tooltip-btn:hover,
.tooltip-btn:focus-visible {
  background: var(--accent-f2);
  color: #0d1117;
  border-color: var(--accent-f2);
  outline: none;
}

.tooltip-popover {
  visibility: hidden;
  opacity: 0;
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(4px);
  width: 270px;
  background: #1c2128;
  border: 1px solid var(--border-focus);
  color: #e6edf3;
  padding: 0.75rem 0.85rem;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.8rem;
  line-height: 1.45;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
  z-index: 100;
  transition: all 0.2s ease;
  pointer-events: none;
}

.tooltip-popover strong {
  color: var(--ink);
  display: inline;
}

.tooltip-container:hover .tooltip-popover,
.tooltip-container:focus-within .tooltip-popover {
  visibility: visible;
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

@media (max-width: 640px) {
  .tooltip-popover {
    left: auto;
    right: -20px;
    transform: translateY(4px);
    width: 240px;
  }
  .tooltip-container:hover .tooltip-popover,
  .tooltip-container:focus-within .tooltip-popover {
    transform: translateY(0);
  }
}

/* Comparison Tables */
.table-wrap {
  margin: 2rem 0;
  overflow-x: auto;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

table.phonetic-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  text-align: left;
}

table.phonetic-table th {
  background: var(--bg-elevated);
  padding: 0.85rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--border);
}

table.phonetic-table td {
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--border-light);
  color: #c9d1d9;
}

table.phonetic-table tr:last-child td {
  border-bottom: none;
}

table.phonetic-table tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

.vowel-cell {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--ink);
}

.mono-num {
  font-family: var(--font-mono);
}

/* Method & Footer */
.method-section {
  padding: 3.5rem 0 2rem;
  border-top: 1px solid var(--border-light);
}

.method-box {
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  font-size: 0.95rem;
  color: var(--ink-soft);
  line-height: 1.6;
}

.method-box h3 {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  color: var(--ink);
  margin-bottom: 0.75rem;
}

.method-box p {
  margin-bottom: 0.85rem;
}

.method-box p:last-child {
  margin-bottom: 0;
}

.method-box a {
  color: var(--accent-f2);
  text-decoration: underline;
  text-underline-offset: 2px;
}

footer.site-footer {
  margin-top: auto;
  padding: 3rem 2rem 4rem;
  border-top: 1px solid var(--border-light);
  text-align: center;
  font-size: 0.88rem;
  color: var(--ink-muted);
}

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

footer.site-footer a:hover {
  color: var(--ink);
  text-decoration: underline;
}

.back-to-top {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1.5rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--ink-soft);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  padding: 0.4rem 0.85rem;
  border-radius: var(--radius-full);
  text-decoration: none;
  transition: all 0.2s ease;
}

.back-to-top:hover {
  color: var(--ink);
  border-color: var(--accent-f2);
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .btn-audio.playing {
    animation: none;
  }
}

/* Mobile optimizations */
@media (max-width: 640px) {
  .topbar {
    padding: 1rem;
  }
  .hero {
    padding: 2.5rem 0 2rem;
  }
  .standfirst {
    font-size: 1.1rem;
  }
  .ledgerline {
    grid-template-columns: 1fr 1fr;
    padding: 1.25rem;
    gap: 1rem;
  }
  .instrument-card {
    padding: 1.25rem;
  }
  canvas#vowelCanvas {
    height: 380px;
  }
  .text-input-wrap {
    flex-direction: column;
  }
  .btn-trace {
    width: 100%;
  }
}