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);
}

.sm-btn {
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border-radius: 999px;
  border: none;
  padding: 0;
  background: #2f6df6;
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

.sm-icon {
  grid-column: 1;
  grid-row: 1;
}

.sm-icon--send {
  width: 20px;
  height: 20px;
}
.sm-icon--send path {
  fill: #fff7e6;
}

.sm-icon--stop {
  width: 16px;
  height: 16px;
  border-radius: 4px;
  background: #fff7e6;
  opacity: 0;
  transform: scale(0.5);
}

@keyframes sm-send {
  0%, 12% {
    opacity: 1;
    transform: scale(1);
  }
  30%, 62% {
    opacity: 0;
    transform: scale(0.5);
  }
  80%, 100% {
    opacity: 1;
    transform: scale(1);
  }
}
@keyframes sm-stop {
  0%, 12% {
    opacity: 0;
    transform: scale(0.5);
  }
  30%, 62% {
    opacity: 1;
    transform: scale(1);
  }
  80%, 100% {
    opacity: 0;
    transform: scale(0.5);
  }
}
.sm-btn.is-demo .sm-icon--send {
  animation: sm-send 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

.sm-btn.is-demo .sm-icon--stop {
  animation: sm-stop 2s cubic-bezier(0.2, 0.8, 0.2, 1) infinite;
}

@media (prefers-reduced-motion: reduce) {
  .sm-btn.is-demo .sm-icon--send {
    animation: none !important;
    opacity: 1 !important;
    transform: scale(1) !important;
  }
  .sm-btn.is-demo .sm-icon--stop {
    animation: none !important;
    opacity: 0 !important;
    transform: scale(0.5) !important;
  }
}