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

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffd23f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.btn {
  position: relative;
  border: 0;
  border-radius: 12px;
  padding: 18px 40px;
  font-weight: 600;
  font-size: 18px;
  line-height: 1;
  font-family: inherit;
  color: #fff7e6;
  background: #17141a;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  transform: scale(1);
  transition: transform 220ms ease-out, box-shadow 220ms ease-out;
}
.btn::after {
  content: "";
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  box-shadow: 0 0 0 0 rgba(47, 109, 246, 0.5), 0 0 0 0 rgba(47, 109, 246, 0.3);
  opacity: 0;
  pointer-events: none;
}

.btn:active {
  transform: scale(0.96);
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.btn:active::after {
  animation: ripple-wave 600ms ease-out;
}

.btn:focus-visible {
  outline: 3px solid #2f6df6;
  outline-offset: 3px;
}

.btn.is-demo {
  animation: press-loop 2s ease-out infinite;
}

.btn.is-demo::after {
  animation: ripple-loop 2s ease-out infinite;
}

@keyframes press-loop {
  0%, 20% {
    transform: scale(1);
    box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  }
  45%, 60% {
    transform: scale(0.96);
    box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  }
  100% {
    transform: scale(1);
    box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  }
}
@keyframes ripple-wave {
  0% {
    box-shadow: 0 0 0 0 rgba(47, 109, 246, 0.55), 0 0 0 0 rgba(47, 109, 246, 0.34);
    opacity: 1;
  }
  20% {
    box-shadow: 0 0 0 8px rgba(47, 109, 246, 0.55), 0 0 0 3px rgba(47, 109, 246, 0.34);
    opacity: 1;
  }
  55% {
    box-shadow: 0 0 0 14px rgba(47, 109, 246, 0.3), 0 0 0 9px rgba(47, 109, 246, 0.2);
    opacity: 0.9;
  }
  85% {
    box-shadow: 0 0 0 16px rgba(47, 109, 246, 0.06), 0 0 0 12px rgba(47, 109, 246, 0.04);
    opacity: 0.2;
  }
  100% {
    box-shadow: 0 0 0 16px rgba(47, 109, 246, 0), 0 0 0 12px rgba(47, 109, 246, 0);
    opacity: 0;
  }
}
@keyframes ripple-loop {
  0%, 40% {
    box-shadow: 0 0 0 0 rgba(47, 109, 246, 0.55), 0 0 0 0 rgba(47, 109, 246, 0.34);
    opacity: 1;
  }
  46% {
    box-shadow: 0 0 0 8px rgba(47, 109, 246, 0.55), 0 0 0 3px rgba(47, 109, 246, 0.34);
    opacity: 1;
  }
  53% {
    box-shadow: 0 0 0 14px rgba(47, 109, 246, 0.3), 0 0 0 9px rgba(47, 109, 246, 0.2);
    opacity: 0.9;
  }
  58% {
    box-shadow: 0 0 0 16px rgba(47, 109, 246, 0.06), 0 0 0 12px rgba(47, 109, 246, 0.04);
    opacity: 0.2;
  }
  63%, 100% {
    box-shadow: 0 0 0 16px rgba(47, 109, 246, 0), 0 0 0 12px rgba(47, 109, 246, 0);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .btn {
    transition: none;
  }
  .btn::after {
    animation: none !important;
    opacity: 0;
  }
  .btn.is-demo {
    animation: none;
    box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
  }
}