:root {
  --bg: #e9e4d8;
  --bg-accent: #d8d1c0;
  --paper: #fffdf7;
  --paper-edge: #e8e2d2;
  --ink: #1f1d1a;
  --muted: #7a7466;
  --accent: #c0392b;
  --accent-ink: #fff6f2;
  --ring: #4b4a47;
  --shadow: rgba(40, 30, 10, 0.35);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1b19;
    --bg-accent: #2a2825;
    --paper: #f7f2e6;
    --paper-edge: #d9d2c0;
    --ink: #1f1d1a;
    --muted: #7a7466;
    --shadow: rgba(0, 0, 0, 0.6);
  }
}

* { box-sizing: border-box; }

html, body { height: 100%; margin: 0; }

body {
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(ellipse at 50% 30%, var(--bg) 0%, var(--bg-accent) 100%);
  display: grid;
  place-items: center;
  overflow: hidden;
}

.scene {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 28px;
  padding: 24px 16px;
}

.calendar {
  position: relative;
  width: min(78vw, 340px);
  aspect-ratio: 3 / 4;
}

.hanger {
  position: absolute;
  left: 50%;
  top: -46px;
  width: 44px;
  height: 44px;
  margin-left: -22px;
  border: 3px solid var(--ring);
  border-bottom: none;
  border-radius: 22px 22px 0 0;
}

.binding {
  position: absolute;
  z-index: 10;
  top: -10px;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-evenly;
  padding: 0 10%;
}

.binding span {
  width: 12px;
  height: 26px;
  border: 3px solid var(--ring);
  border-radius: 7px;
  background: transparent;
}

.sheets {
  position: absolute;
  inset: 0;
  perspective: 900px;
}

.sheet {
  position: absolute;
  inset: 0;
  background: var(--paper);
  border-radius: 4px;
  box-shadow: 0 10px 28px var(--shadow);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  transform-origin: 50% 0%;
  backface-visibility: hidden;
}

.sheet.under-1 { transform: translate(2px, 3px); background: var(--paper-edge); }
.sheet.under-2 { transform: translate(4px, 6px); background: var(--paper-edge); opacity: .8; }

.sheet.current { z-index: 2; }
.sheet.previous { z-index: 3; }

.sheet::before {
  /* perforation line below the binding */
  content: "";
  position: absolute;
  top: 18px;
  left: 0;
  right: 0;
  border-top: 2px dashed rgba(0, 0, 0, 0.15);
}

.sheet .head {
  margin-top: 20px;
  padding: 10px 16px;
  background: var(--accent);
  color: var(--accent-ink);
  font-size: 0.9rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  text-align: center;
}

.sheet .body {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 0 12px;
}

.sheet .number {
  font-size: clamp(5rem, 36vw, 11rem);
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.04em;
}

.sheet .number.small { font-size: clamp(2.2rem, 12vw, 4rem); letter-spacing: 0; }

.sheet .unit {
  margin-top: 6px;
  font-size: 1.1rem;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--muted);
}

.sheet .foot {
  padding: 12px 16px 16px;
  text-align: center;
  font-size: 0.85rem;
  color: var(--muted);
  border-top: 1px solid rgba(0, 0, 0, 0.08);
}

.caption {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  text-align: center;
}

@media (prefers-color-scheme: dark) {
  .caption { color: #a39c8c; }
}

/* --- Tear-off animation --- */

.sheet.tearing {
  animation: tear 1.6s cubic-bezier(0.55, 0.05, 0.75, 0.6) forwards;
  pointer-events: none;
}

@keyframes tear {
  0% {
    transform: rotateX(0deg);
    opacity: 1;
  }
  18% {
    /* grab the bottom edge and pull it up and out */
    transform: rotateX(32deg);
    opacity: 1;
  }
  38% {
    /* tear along the perforation */
    transform: translateY(10px) rotateZ(3deg) rotateX(70deg);
    box-shadow: 0 30px 50px var(--shadow);
    opacity: 1;
  }
  70% {
    opacity: 1;
  }
  100% {
    /* fall off the bottom of the screen */
    transform: translateY(120vh) translateX(40px) rotateZ(25deg) rotateX(70deg);
    opacity: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .sheet.tearing { animation: fade-out 0.4s ease forwards; }
  @keyframes fade-out { to { opacity: 0; } }
}