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

.stage {
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
}

.btn {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  border: 0;
  border-radius: 14px;
  padding: 24px 64px;
  font: 600 22px/1 inherit;
  color: #fff;
  background: #2f6df6;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: filter 150ms;
}
.btn:hover {
  filter: brightness(1.06);
}
.btn:active {
  filter: brightness(0.96);
}
.btn::after {
  content: "";
  position: absolute;
  left: var(--x, 50%);
  top: var(--y, 50%);
  width: var(--d, 0);
  height: var(--d, 0);
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.45);
  transform: translate(-50%, -50%) scale(0);
  opacity: 0;
  pointer-events: none;
}
.btn.is-rippling::after {
  animation: ripple 600ms cubic-bezier(0.2, 0.8, 0.2, 1) forwards;
}
.btn.is-demo::after {
  --d: 520px;
  animation: ripple-loop 2s ease-out infinite;
}

@keyframes ripple {
  from {
    transform: translate(-50%, -50%) scale(0);
    opacity: 1;
  }
  to {
    transform: translate(-50%, -50%) scale(1);
    opacity: 0;
  }
}
@keyframes ripple-loop {
  0% {
    transform: translate(-50%, -50%) scale(0);
    opacity: 1;
  }
  40% {
    transform: translate(-50%, -50%) scale(0.7);
    opacity: 0.85;
  }
  60% {
    transform: translate(-50%, -50%) scale(1);
    opacity: 0;
  }
  100% {
    transform: translate(-50%, -50%) scale(1);
    opacity: 0;
  }
}
@media (prefers-reduced-motion: reduce) {
  .btn::after {
    animation: none !important;
    opacity: 0;
  }
  .btn:active {
    filter: brightness(0.88);
  }
}