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);
}

.btn {
  border: 0;
  border-radius: 12px;
  padding: 16px 34px;
  background: #fff7e6;
  color: #17141a;
  font-weight: 700;
  font-size: clamp(15px, 4vw, 18px);
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.a-jelly.is-jellying {
  animation: jelly 600ms cubic-bezier(0.68, -0.55, 0.27, 1.55) 1;
}

.a-jelly.is-demo {
  animation: jelly-loop 2s cubic-bezier(0.68, -0.55, 0.27, 1.55) infinite;
}

@keyframes jelly {
  0% {
    transform: scale(1, 1);
  }
  20% {
    transform: scale(1.25, 0.75);
  }
  40% {
    transform: scale(0.75, 1.25);
  }
  60% {
    transform: scale(1.15, 0.85);
  }
  80% {
    transform: scale(0.95, 1.05);
  }
  100% {
    transform: scale(1, 1);
  }
}
@keyframes jelly-loop {
  0%, 60% {
    transform: scale(1, 1);
  }
  68% {
    transform: scale(1.25, 0.75);
  }
  76% {
    transform: scale(0.75, 1.25);
  }
  84% {
    transform: scale(1.15, 0.85);
  }
  92% {
    transform: scale(0.95, 1.05);
  }
  100% {
    transform: scale(1, 1);
  }
}
@media (prefers-reduced-motion: reduce) {
  .a-jelly.is-jellying, .a-jelly.is-demo {
    animation: none;
  }
}