:root {
  --bg: #f4f8f8;
  --card: #ffffff;
  --text: #12302f;
  --muted: #5b7473;
  --border: #d6e3e2;
  --accent: #0ea5a4;
  --accent-strong: #0b8584;
  --accent-soft: #ccf1f0;
  --done: #9ad7b0;
  --done-stroke: #4fa771;
  --tooth: #ffffff;
  --tooth-alt: #eef3f3;
  --tooth-stroke: #b5c6c5;
  --gum: #f6c9cf;
  --flash-bg: rgba(14, 165, 164, 0.92);
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1716;
    --card: #152322;
    --text: #e3f1f0;
    --muted: #8fa9a7;
    --border: #26403e;
    --accent: #2dd4d3;
    --accent-strong: #5ee6e5;
    --accent-soft: #123b3a;
    --done: #2f6b48;
    --done-stroke: #58b47d;
    --tooth: #e9efee;
    --tooth-alt: #c9d6d5;
    --tooth-stroke: #6f8886;
    --gum: #5a3238;
    --flash-bg: rgba(13, 120, 119, 0.94);
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

html, body { margin: 0; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.4;
  -webkit-tap-highlight-color: transparent;
}

.app {
  max-width: 920px;
  margin: 0 auto;
  padding: 16px 16px calc(24px + env(safe-area-inset-bottom));
}

.top h1 {
  margin: 4px 0 16px;
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.stage {
  display: grid;
  gap: 16px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 16px;
}

@media (min-width: 720px) {
  .stage { grid-template-columns: 1fr 1fr; align-items: center; padding: 24px; }
}

.diagram svg {
  display: block;
  width: 100%;
  max-width: 340px;
  max-height: 52vh;
  margin: 0 auto;
}

/* Teeth diagram */
.gum { fill: none; stroke: var(--gum); stroke-linecap: round; }
.tooth {
  fill: var(--tooth);
  stroke: var(--tooth-stroke);
  stroke-width: 1.2;
  transition: fill 0.35s, stroke 0.35s;
}
.tooth.alt { fill: var(--tooth-alt); }
.tooth.done { fill: var(--done); stroke: var(--done-stroke); }
.tooth.active {
  fill: var(--accent);
  stroke: var(--accent-strong);
  stroke-width: 2;
  animation: pulse 1.2s ease-in-out infinite;
}
@keyframes pulse { 50% { opacity: 0.6; } }

.zone-num {
  font-size: 15px;
  font-weight: 700;
  fill: var(--muted);
  text-anchor: middle;
  dominant-baseline: central;
  transition: fill 0.3s;
}
.zone-num.active { fill: var(--accent); font-size: 19px; }
.zone-num.done { fill: var(--done-stroke); }
.arch-label, .side-label {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.12em;
  fill: var(--muted);
  text-anchor: middle;
  dominant-baseline: central;
}
.side-label { font-size: 13px; letter-spacing: 0; }

/* Readout */
.readout { text-align: center; }
.zone-step { color: var(--muted); font-size: 0.9rem; min-height: 1.3em; }
.zone-label { font-size: 1.5rem; font-weight: 700; margin: 2px 0 4px; }
.zone-time {
  font-size: clamp(3.5rem, 15vw, 5.5rem);
  font-weight: 800;
  font-variant-numeric: tabular-nums;
  line-height: 1;
  margin-bottom: 12px;
}

.bar {
  height: 12px;
  border-radius: 999px;
  background: var(--accent-soft);
  overflow: hidden;
}
.bar.thin { height: 6px; }
.bar-fill {
  height: 100%;
  width: 0%;
  background: var(--accent);
  border-radius: inherit;
}
.bar-fill.total { background: var(--done-stroke); }

.total-row {
  display: flex;
  justify-content: space-between;
  margin: 14px 2px 6px;
  color: var(--muted);
  font-size: 0.9rem;
  font-variant-numeric: tabular-nums;
}

.controls {
  display: flex;
  gap: 10px;
  margin-top: 20px;
}

.btn {
  flex: 1;
  font: inherit;
  font-weight: 600;
  font-size: 1.05rem;
  padding: 14px 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
}
.btn.primary {
  flex: 2;
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}
@media (prefers-color-scheme: dark) { .btn.primary { color: #062221; } }
.btn:active { transform: scale(0.98); }
.btn:focus-visible { outline: 3px solid var(--accent-strong); outline-offset: 2px; }

/* Settings */
.settings {
  margin-top: 16px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 16px;
}
.settings h2 { margin: 0 0 12px; font-size: 1.05rem; }
.settings.locked { opacity: 0.55; pointer-events: none; }

.field { margin: 0 0 16px; border: 0; padding: 0; }
.field > label, .field > legend {
  display: flex;
  justify-content: space-between;
  width: 100%;
  font-weight: 600;
  margin-bottom: 8px;
  padding: 0;
}
.field output { font-variant-numeric: tabular-nums; color: var(--accent-strong); }
input[type="range"] { width: 100%; accent-color: var(--accent); }

.segmented { display: flex; gap: 8px; }
.segmented label { flex: 1; margin: 0; }
.segmented input { position: absolute; opacity: 0; pointer-events: none; }
.segmented span {
  display: block;
  text-align: center;
  padding: 10px 0;
  border-radius: 12px;
  border: 1px solid var(--border);
  font-weight: 700;
  cursor: pointer;
}
.segmented input:checked + span { background: var(--accent); border-color: var(--accent); color: #fff; }
.segmented input:focus-visible + span { outline: 3px solid var(--accent-strong); outline-offset: 2px; }

.hint { margin: 6px 0 0; font-size: 0.85rem; color: var(--muted); }

.toggles { display: flex; flex-wrap: wrap; gap: 8px; }
.toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  cursor: pointer;
  font-size: 0.95rem;
}
.toggle input { accent-color: var(--accent); width: 18px; height: 18px; margin: 0; }

/* Full-screen switch flash */
.flash {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  background: var(--flash-bg);
  color: #fff;
  opacity: 0;
  pointer-events: none;
  z-index: 10;
  text-align: center;
  padding: 16px;
}
.flash.show { animation: flash 1.6s ease-out; }
@keyframes flash {
  0% { opacity: 0; }
  8% { opacity: 1; }
  20% { opacity: 0.75; }
  30% { opacity: 1; }
  70% { opacity: 1; }
  100% { opacity: 0; }
}
.flash-text small { display: block; font-size: 1.2rem; opacity: 0.9; }
.flash-text strong { display: block; font-size: clamp(2rem, 9vw, 3.5rem); line-height: 1.1; }

@media (prefers-reduced-motion: reduce) {
  .tooth.active { animation: none; }
  .flash.show { animation-duration: 2.2s; animation-timing-function: steps(2, jump-none); }
}