:root {
  --bg: #fdf8f4;
  --surface: #ffffff;
  --border: #f0e0d8;
  --text: #2d2d2d;
  --text-dim: #888888;
  --accent: #e8578a;
  --accent-light: #fce4ec;
  --accent-glow: rgba(232, 87, 138, 0.3);
  --blue: #4a90d9;
  --red: #e8578a;
  --canvas-bg: #fafafa;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: "Inter", system-ui, -apple-system, sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.5rem;
}

header {
  text-align: center;
  margin-bottom: 1.5rem;
  position: relative;
}

header h1 {
  font-size: 1.4rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--text);
}

header p {
  color: var(--text-dim);
  font-size: 0.85rem;
  margin-top: 0.25rem;
}

.info-btn {
  position: absolute;
  top: 0;
  right: -3rem;
  background: var(--accent-light);
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 2rem;
  height: 2rem;
  font-size: 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  transition: all 0.15s;
  color: var(--accent);
}

.info-btn:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* ── Main layout ── */
.main {
  display: grid;
  grid-template-columns: 520px 400px 180px;
  gap: 1.5rem;
  align-items: start;
  justify-content: center;
  width: 100%;
  max-width: 1200px;
}

.chart-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  flex-shrink: 0;
}

.tract-container {
}
#tract {
  width: 100%;
  max-width: 500px;
  aspect-ratio: 600 / 500;
}

.tract-label {
  color: var(--text-dim);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  text-align: center;
  margin-top: 0.4rem;
}

canvas {
  display: block;
  border-radius: 8px;
}

.sidebar {
  min-width: 180px;
  max-width: 180px;
  display: flex;
  flex-direction: column;
  gap: 1rem;
  min-width: 200px;
}

.current-vowel {
  min-height: 160px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
}

.current-vowel .symbol {
  font-size: 4rem;
  line-height: 1;
  font-weight: 700;
  color: var(--accent);
  transition: color 0.15s;
}

.current-vowel .symbol.silent {
  color: var(--text-dim);
  opacity: 0.3;
}

.current-vowel .name {
  color: var(--text-dim);
  font-size: 0.8rem;
  margin-top: 0.5rem;
}

.formant-display {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  font-family: "JetBrains Mono", "SF Mono", monospace;
  font-size: 0.85rem;
}

.formant-display .label {
  color: var(--text-dim);
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.formant-display .value {
  font-size: 1.1rem;
  margin-top: 0.1rem;
  margin-bottom: 0.5rem;
  color: var(--text);
}

.controls {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

button {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.6rem 1.2rem;
  font-size: 0.9rem;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}

button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

button.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  font-weight: 600;
}

button.active:hover {
  opacity: 0.9;
}

button:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.status {
  font-size: 0.75rem;
  color: var(--text-dim);
  text-align: center;
}

.status .dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--text-dim);
  margin-right: 4px;
  vertical-align: middle;
}

.status .dot.live {
  background: var(--red);
  box-shadow: 0 0 6px var(--red);
  animation: pulse 1.2s ease-in-out infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.spectrum-container {
  width: 100%;
  max-width: 1200px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  margin-top: 1.5rem;
}

#spectrum {
  width: 100%;
  height: 200px;
  border-radius: 8px;
}

/* ── Modal ── */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.4);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.modal-overlay.visible {
  display: flex;
}

.modal {
  background: #fff;
  border-radius: 16px;
  padding: 2rem;
  max-width: 520px;
  width: 90%;
  max-height: 85vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
  color: var(--text);
  line-height: 1.6;
}

.modal h2 {
  font-size: 1.3rem;
  margin-bottom: 0.75rem;
  color: var(--accent);
}

.modal h3 {
  font-size: 1rem;
  margin-top: 1.2rem;
  margin-bottom: 0.4rem;
  color: var(--text);
}

.modal ul {
  padding-left: 1.2rem;
  font-size: 0.88rem;
}

.modal li {
  margin-bottom: 0.2rem;
}

.modal p {
  font-size: 0.9rem;
}

.modal a {
  color: var(--accent);
  text-decoration: none;
}

.modal a:hover {
  text-decoration: underline;
}

.modal-close {
  position: absolute;
  top: 0.75rem;
  right: 0.75rem;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-dim);
  width: 2rem;
  height: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  padding: 0;
}

.modal-close:hover {
  background: var(--accent-light);
  color: var(--accent);
}

/* ── Start overlay ── */
.start-overlay {
  position: fixed;
  inset: 0;
  background: rgba(253, 248, 244, 0.92);
  z-index: 999;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: opacity 0.3s ease;
}

.start-overlay.hidden {
  opacity: 0;
  pointer-events: none;
}

.start-prompt {
  text-align: center;
  animation: breathe 2s ease-in-out infinite;
}

.start-icon {
  font-size: 4rem;
  margin-bottom: 1rem;
}

.start-text {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--text);
}

.start-sub {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-top: 0.5rem;
}

@keyframes breathe {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.04); }
}

/* ── Responsive: Tablet ── */
@media (max-width: 1024px) {
  .main {
    grid-template-columns: auto auto;
  }
  .sidebar {
  min-width: 180px;
  max-width: 180px;
    grid-column: 1 / -1;
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    align-items: flex-start;
  }
  .sidebar > * {
    flex: 1;
    min-width: 160px;
    max-width: 240px;
  }
}

/* ── Responsive: Mobile ── */
@media (max-width: 768px) {
  body {
    padding: 1rem 0.75rem;
  }

  header h1 {
    font-size: 1.1rem;
  }

  header p {
    font-size: 0.75rem;
  }

  .info-btn {
    right: -2.5rem;
    width: 1.75rem;
    height: 1.75rem;
    font-size: 0.85rem;
  }

  .main {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .chart-container {
    width: 100%;
    padding: 0.75rem;
  }

  #chart {
    width: 100% !important;
    height: auto !important;
  }

  #tract {
    width: 100% !important;
    height: auto !important;
    max-width: 100%;
    margin: 0 auto;
    display: block;
  }

  .tract-container {
    display: flex;
    flex-direction: column;
    align-items: center;
  }

  .sidebar {
    flex-direction: column;
    align-items: stretch;
    min-width: unset;
    max-width: 100%;
    width: 100%;
  }

  .sidebar > * {
    max-width: 100%;
    min-width: unset;
    width: 100%;
  }

  .current-vowel {
  min-height: 160px;
  display: flex;
  flex-direction: column;
  justify-content: center;
    padding: 1rem;
  }

  .current-vowel .symbol {
    font-size: 3rem;
  }

  .spectrum-container {
    margin-top: 1rem;
    padding: 0.75rem;
  }

  #spectrum {
    height: 150px;
  }

  .formant-display .value {
    font-size: 1rem;
  }

  .modal {
    padding: 1.5rem;
    max-width: 95%;
  }
}

.data-row {
  min-height: 1.8rem;
}
.data-value {
  min-width: 5rem;
  display: inline-block;
  text-align: right;
}