html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.sf-board {
  display: flex;
  gap: 8px;
  perspective: 600px;
}

.sf-char {
  display: inline-block;
  width: clamp(32px, 9vw, 48px);
  padding: 8px 0;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.08);
  color: #fff7e6;
  font: 800 clamp(20px, 6vw, 28px)/1 -apple-system, "Segoe UI", sans-serif;
  text-align: center;
  transform-origin: center;
  transform: rotateX(90deg);
  opacity: 0;
  filter: blur(3px);
}

@keyframes sf-flip {
  0% {
    transform: rotateX(90deg);
    opacity: 0;
    filter: blur(3px);
  }
  15% {
    filter: blur(4px);
  }
  30% {
    transform: rotateX(0deg);
    opacity: 1;
    filter: blur(0);
  }
  90% {
    transform: rotateX(0deg);
    opacity: 1;
    filter: blur(0);
  }
  95% {
    filter: blur(4px);
  }
  100% {
    transform: rotateX(90deg);
    opacity: 0;
    filter: blur(3px);
  }
}
.sf-board.is-demo .sf-char {
  animation: sf-flip 2s steps(3, end) infinite;
}

.sf-board.is-demo .sf-char:nth-child(1) {
  animation-delay: 0ms;
}

.sf-board.is-demo .sf-char:nth-child(2) {
  animation-delay: 120ms;
}

.sf-board.is-demo .sf-char:nth-child(3) {
  animation-delay: 240ms;
}

.sf-board.is-demo .sf-char:nth-child(4) {
  animation-delay: 360ms;
}

@media (prefers-reduced-motion: reduce) {
  .sf-char,
  .sf-board.is-demo .sf-char {
    animation: none !important;
    opacity: 1 !important;
    transform: none !important;
    filter: none !important;
  }
}