:root {
  --hall-bg: 10 10 11;
  --amber: 255 176 59;
  --ink: 236 233 225;
  --card-bg: 30 30 32;
  --card-edge: 6 6 7;
  --frame: 46 46 49;
  --error: 255 99 87;

  --card-h: clamp(56px, 12vw, 92px);
  --card-w: clamp(40px, 8.5vw, 68px);

  --ease-fall: cubic-bezier(0.55, 0, 0.85, 0.35);
}

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

body {
  min-height: 100vh;
  background: radial-gradient(120% 90% at 50% 0%, #1a1a1d 0%, rgb(var(--hall-bg)) 55%);
  color: rgb(var(--ink));
  font-family: 'Archivo', system-ui, sans-serif;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 3rem 1.25rem;
}

.hall {
  width: 100%;
  max-width: 720px;
  text-align: center;
}

.eyebrow {
  font-family: 'Space Mono', monospace;
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: rgb(var(--amber));
  margin-bottom: 0.75rem;
}

h1 {
  font-size: clamp(1.9rem, 6vw, 2.6rem);
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.lede {
  color: rgb(var(--ink) / 0.55);
  font-size: 1rem;
  max-width: 42ch;
  margin: 0 auto 2.25rem;
  line-height: 1.6;
}

/* ---------- Picker ---------- */
.picker {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  max-width: 420px;
  margin: 0 auto 1rem;
}

.picker label {
  font-size: 0.78rem;
  font-weight: 600;
  color: rgb(var(--ink) / 0.5);
  text-align: left;
}

.picker-row {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
}

input[type='datetime-local'] {
  flex: 1;
  min-width: 200px;
  padding: 0.7rem 0.9rem;
  font-family: 'Space Mono', monospace;
  font-size: 0.9rem;
  color: rgb(var(--ink));
  background: rgb(var(--card-bg));
  border: 1px solid rgb(var(--frame));
  border-radius: 10px;
  outline: none;
  transition: border-color 200ms ease;
}

input[type='datetime-local']::-webkit-calendar-picker-indicator {
  filter: invert(0.8);
  cursor: pointer;
}

input[type='datetime-local']:focus {
  border-color: rgb(var(--amber) / 0.6);
}

#start-btn {
  padding: 0.7rem 1.4rem;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 700;
  color: rgb(var(--hall-bg));
  background: rgb(var(--amber));
  border: none;
  border-radius: 10px;
  cursor: pointer;
  transition:
    transform 150ms cubic-bezier(0.25, 0.46, 0.45, 0.94),
    box-shadow 200ms ease;
}

@media (hover: hover) and (pointer: fine) {
  #start-btn:hover {
    transform: scale(1.03);
    box-shadow: 0 10px 24px -10px rgb(var(--amber) / 0.6);
  }
}

#start-btn:active {
  transform: scale(0.97);
}

.status {
  min-height: 1.4rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: rgb(var(--amber));
  margin-bottom: 1.5rem;
}

.status.is-error {
  color: rgb(var(--error));
}

/* ---------- Board ---------- */
.board[hidden] {
  display: none;
}

.board {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: clamp(0.5rem, 2.5vw, 1.25rem);
  padding: 1.75rem clamp(1rem, 4vw, 2rem);
  background: rgb(var(--frame));
  border-radius: 18px;
  box-shadow:
    inset 0 2px 0 rgb(255 255 255 / 0.06),
    0 30px 60px -25px rgb(0 0 0 / 0.8);
}

.unit {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
}

.unit-label {
  font-family: 'Space Mono', monospace;
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: rgb(var(--ink) / 0.45);
}

.colon {
  font-size: clamp(1.5rem, 4vw, 2.2rem);
  font-weight: 800;
  color: rgb(var(--ink) / 0.25);
  align-self: center;
  margin-top: calc(var(--card-h) / 2 - 0.7rem);
}

.flaps {
  display: flex;
  gap: 4px;
}

/* ---------- Flap digit ---------- */
.flap {
  position: relative;
  width: var(--card-w);
  height: var(--card-h);
  perspective: calc(var(--card-h) * 4);
  border-radius: 6px;
  background: rgb(var(--card-edge));
}

.flap__half {
  position: absolute;
  left: 0;
  width: 100%;
  height: 50%;
  overflow: hidden;
  background: rgb(var(--card-bg));
}

.flap__half--top {
  top: 0;
  border-radius: 6px 6px 0 0;
}

.flap__half--bottom {
  bottom: 0;
  border-radius: 0 0 6px 6px;
}

.flap__glyph {
  position: absolute;
  left: 0;
  width: 100%;
  height: var(--card-h);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Space Mono', monospace;
  font-weight: 700;
  font-size: calc(var(--card-h) * 0.52);
  color: rgb(var(--ink));
}

.flap__half--top .flap__glyph {
  top: 0;
}

.flap__half--bottom .flap__glyph {
  top: calc(var(--card-h) / -2);
}

.flap__leaf {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 50%;
  overflow: hidden;
  background: rgb(var(--card-bg));
  border-radius: 6px 6px 0 0;
  transform-origin: bottom center;
  backface-visibility: hidden;
  z-index: 5;
  box-shadow: 0 1px 0 rgb(0 0 0 / 0.5);
}

.flap__leaf .flap__glyph {
  top: 0;
}

.flap__hinge {
  position: absolute;
  top: calc(50% - 1px);
  left: 0;
  width: 100%;
  height: 2px;
  background: rgb(0 0 0 / 0.5);
  z-index: 6;
  pointer-events: none;
}

@media (max-width: 480px) {
  .board {
    padding: 1.25rem 0.75rem;
  }
}