/* One 166 × 244 sheet. Its lower half folds up over the upper half. */
.pf-stage {
  position: relative;
  width: min(280px, 100%);
  height: 280px;
  margin-inline: auto;
  perspective: 720px;
  perspective-origin: 50% 50%;
  /* Keep overflow visible: the rotating flap comes toward the viewer. */
  overflow: visible;
}
.pf-sheet {
  position: absolute;
  top: 18px;
  left: calc(50% - 83px);
  width: 166px;
  height: 244px;
  transform-style: preserve-3d;
  /* No scale, position, or rotation change during the reveal. */
}
.pf-fixed, .pf-face {
  position: absolute;
  box-sizing: border-box;
  width: 166px;
  height: 122px;
  border: 0;
  background: transparent;
}
.pf-fixed {
  inset: 0 auto auto 0;
  display: grid;
  place-items: center;
  filter: drop-shadow(2px 3px 2px #34382d25);
}
.pf-fixed > .paper-art { position: absolute; inset: 0; }
.pf-rank {
  position: relative;
  color: var(--paper-print);
  font: 700 38px/1.35 'Noto Serif KR', 'AppleMyungjo', 'Batang', serif;
  letter-spacing: 9px;
  padding-left: 9px;
  white-space: nowrap;
  /* Printed at creation. Never faded, delayed, scaled, or swapped. */
}
.pf-flap {
  position: absolute;
  inset: 0 auto auto 0;
  width: 166px;
  height: 122px;
  transform-origin: 50% 100%;
  transform-style: preserve-3d;
  transform: rotateX(0deg);
}
.pf-face {
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}
.pf-front {
  /* Tiny separation avoids coincident surfaces at the closed endpoint. */
  transform: translateZ(.2px);
  filter: drop-shadow(0 3px 1px #152b5338);
}
.pf-back {
  transform: rotateX(180deg) translateZ(.2px);
  filter: drop-shadow(2px 3px 2px #34382d25);
}
.pf-back > .paper-art { transform: scaleY(-1); }
.pf-back::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 6px;
  border-top: 1px solid var(--paper-line);
  background: linear-gradient(#c8bf9f4d, transparent);
}