* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: #eef6fb;
  color: #123;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
}

.screen {
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 24px;
  text-align: center;
}

.screen.active {
  display: flex;
}

h1 {
  font-size: 1.8rem;
  margin-bottom: 8px;
}

h2 {
  font-size: 1.6rem;
  margin: 12px 0 0;
  color: #1e6091;
}

.hint {
  max-width: 320px;
  color: #567;
  font-size: 0.9rem;
  margin-top: 32px;
}

/* Duration picker */
.duration-picker {
  display: flex;
  align-items: center;
  gap: 24px;
  margin: 32px 0;
}

.duration-display {
  font-size: 3rem;
  font-variant-numeric: tabular-nums;
  min-width: 140px;
}

.round-btn {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  border: none;
  background: #1e6091;
  color: white;
  font-size: 1.8rem;
  line-height: 1;
  cursor: pointer;
}

.round-btn:active {
  background: #144a70;
}

.primary-btn {
  background: #2a9d8f;
  color: white;
  border: none;
  border-radius: 16px;
  padding: 16px 48px;
  font-size: 1.4rem;
  cursor: pointer;
  box-shadow: 0 4px 10px rgba(0,0,0,0.15);
}

.primary-btn:active {
  transform: translateY(2px);
}

.secondary-btn {
  margin-top: 32px;
  background: transparent;
  color: #c0392b;
  border: 2px solid #c0392b;
  border-radius: 16px;
  padding: 10px 32px;
  font-size: 1.1rem;
  cursor: pointer;
}

/* Running screen */
.total-time {
  font-size: 1.2rem;
  color: #567;
  font-variant-numeric: tabular-nums;
}

.mouth {
  width: min(70vw, 280px);
  height: min(70vw, 280px);
  margin: 16px 0;
}

.segment-time {
  font-size: 3.2rem;
  font-variant-numeric: tabular-nums;
  color: #1e6091;
}

/* faint outline of the whole tunnel shape: outer rim + inner rim + ends */
.tunnel-base {
  fill: none;
  stroke: #cdd9e0;
  stroke-width: 2;
}

/* fills the band between outer and inner rim -> "top" (chewing surface) */
.tunnel-band {
  fill: transparent;
  stroke: none;
  transition: fill 0.25s ease;
}

.tunnel-band.on {
  fill: rgba(42, 157, 143, 0.35);
}

/* outer rim -> "front"; inner rim -> "back" */
.tunnel-rim {
  fill: none;
  stroke: transparent;
  stroke-width: 6;
  stroke-linecap: round;
  transition: stroke 0.25s ease;
}

.tunnel-rim.on {
  stroke: #2a9d8f;
}

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

.dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #cdd9e0;
}

.dot.done {
  background: #2a9d8f;
}

.dot.active {
  background: #e76f51;
}