/* Tile Wrapper */
.tile {
  width: var(--tile-size);
  height: var(--tile-size);
  perspective: 400px;
  background: #111;
  border-radius: 3px;
}

/* Inner Container (transform target) */
.tile-inner {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
}

/* Tile Faces */
.tile-front,
.tile-back {
  position: absolute;
  inset: 1px;
  backface-visibility: hidden;
  background: #222;
  border-radius: 2px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow:
    inset 0 1px 3px rgba(0, 0, 0, 0.5),
    inset 0 -1px 1px rgba(255, 255, 255, 0.02);
  overflow: hidden;
}

.tile-front span,
.tile-back span {
  font-size: calc(var(--tile-size) * 0.52);
  font-weight: 700;
  color: #FFFFFF;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  line-height: 1;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

.tile-back {
  transform: rotateX(180deg);
}

/* Horizontal Split Line — subtle mechanical seam */
.tile-front::after,
.tile-back::after {
  content: '';
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  height: 1px;
  background: rgba(0, 0, 0, 0.3);
  pointer-events: none;
}

/* Highlight Sweep (metallic reflection during flip) */
.tile-front::before,
.tile-back::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    180deg,
    transparent 0%,
    rgba(255, 255, 255, 0.08) 45%,
    rgba(255, 255, 255, 0.15) 50%,
    rgba(255, 255, 255, 0.08) 55%,
    transparent 100%
  );
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.15s;
}

/* 3D Flip Animation */
.tile-inner.flipping {
  animation: tileFlip var(--flip-duration, 300ms) ease-in-out forwards;
}

.tile-inner.flipping .tile-front::before,
.tile-inner.flipping .tile-back::before {
  opacity: 1;
}

@keyframes tileFlip {
  0% {
    transform: rotateX(0deg);
  }
  50% {
    transform: rotateX(-90deg);
  }
  100% {
    transform: rotateX(-180deg);
  }
}

/* GPU compositing hint during animation only */
.tile-inner.flipping,
.tile.scrambling .tile-inner {
  will-change: transform;
}