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

:root {
  --bg: #0f0f0f;
  --surface: #1a1a1a;
  --border: rgba(255, 255, 255, 0.08);
  --text: #ffffff;
  --muted: rgba(255, 255, 255, 0.45);
  --accent: #dc2626;
}

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
  user-select: none;
  overflow: hidden;
}

.stage {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2rem;
  padding: 5rem 1.5rem 3rem;
}

.talk-btn {
  --size: min(58vw, 42vh, 280px);
  width: var(--size);
  height: var(--size);
  border-radius: 50%;
  background: radial-gradient(circle at 30% 30%, #2a2a2a, #141414);
  border: 2px solid rgba(220, 38, 38, 0.35);
  color: var(--muted);
  font: inherit;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
  box-shadow: 0 10px 30px rgba(0,0,0,0.5);
}

.talk-btn .talk-icon {
  font-size: clamp(3.5rem, 12vw, 6rem);
  line-height: 1;
  filter: grayscale(0.3);
  transition: filter 0.2s ease;
}
.talk-btn .talk-label {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.25em;
  text-transform: uppercase;
}

.talk-btn[aria-pressed="true"] {
  background: radial-gradient(circle at 30% 30%, #b91c1c, #7f1d1d);
  border-color: var(--accent);
  color: #fff;
  animation: pulse 1.4s ease-out infinite;
}
.talk-btn[aria-pressed="true"] .talk-icon { filter: none; }

@keyframes pulse {
  0%, 100% { box-shadow: 0 10px 30px rgba(0,0,0,0.5), 0 0 0 0 rgba(220, 38, 38, 0.5); }
  50%      { box-shadow: 0 10px 30px rgba(0,0,0,0.5), 0 0 0 22px rgba(220, 38, 38, 0); }
}

.meter {
  width: min(88vw, 500px);
  height: 40px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  display: block;
}

.controls {
  width: min(88vw, 500px);
}

.field-label {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.5rem;
}
.field-label #gain-value {
  color: var(--text);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

input[type="range"] {
  width: 100%;
  accent-color: var(--accent);
}

.hint {
  max-width: 400px;
  text-align: center;
  font-size: 0.78rem;
  color: var(--muted);
  line-height: 1.5;
}

/* Top bar */
.top-bar {
  position: fixed;
  top: env(safe-area-inset-top, 0);
  right: env(safe-area-inset-right, 0);
  padding: 0.85rem 1rem;
  display: flex;
  align-items: center;
  gap: 0.55rem;
  z-index: 20;
}

.back-link {
  color: var(--muted);
  font-size: 0.65rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  text-decoration: none;
  padding: 0.4rem 0.5rem;
  transition: color 0.15s ease;
}
.back-link:hover { color: var(--text); }

.cal-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--muted);
  font: inherit;
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  padding: 0.42rem 0.7rem;
  border-radius: 6px;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}
.cal-btn:hover { color: var(--text); border-color: var(--muted); }

/* Modal */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.25rem;
}
.modal[hidden] { display: none; }

.modal-panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 1.5rem;
  max-width: 380px;
  width: 100%;
}

.modal-panel h2 {
  font-size: 1.2rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  margin-bottom: 0.5rem;
}

.modal-hint {
  font-size: 0.82rem;
  color: var(--muted);
  line-height: 1.55;
}