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

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

.btn {
  border: 0;
  border-radius: 12px;
  padding: 16px 40px;
  background: #0a4fe8;
  color: #fff;
  font-weight: 700;
  font-size: clamp(15px, 4vw, 18px);
  line-height: 1;
  font-family: inherit;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.a-pulse {
  animation: pulse 2s ease-out infinite;
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
    opacity: 1;
  }
  50% {
    transform: scale(1.06);
    opacity: 0.92;
  }
}
@media (prefers-reduced-motion: reduce) {
  .a-pulse {
    animation: none;
  }
}