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 {
  box-sizing: border-box;
  position: relative;
  width: 240px;
  height: 64px;
  border: none;
  border-radius: 999px;
  color: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  font-weight: 700;
  font-size: 18px;
  cursor: pointer;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), box-shadow 220ms cubic-bezier(0.2, 0.8, 0.2, 1);
}

.btn__bg {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  width: 720px;
  background: repeating-linear-gradient(to right, #ff9ecb 0 58px, #d9d4ea 64px 118px, #cddfe6 124px 178px, #ff9ecb 184px 240px);
}

.btn__label {
  position: relative;
  z-index: 1;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 18px 28px rgba(23, 20, 26, 0.4);
}

.btn:focus-visible {
  outline: 3px solid #ffd23f;
  outline-offset: 4px;
}

.stage.is-demo .btn__bg {
  animation: gradient-flow 2s linear infinite;
}

@keyframes gradient-flow {
  0% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(-240px);
  }
}
@media (prefers-reduced-motion: reduce) {
  .stage.is-demo .btn__bg {
    animation: none;
    transform: translateX(-120px);
  }
}