:root {
  --ring: rgba(20, 184, 166, 0.45);
}
button:focus-visible, input:focus-visible {
  outline: 0;
  box-shadow: 0 0 0 4px var(--ring);
  transition: box-shadow .15s ease;
}

@keyframes pulse {
  0%,100% { filter: brightness(1.0); transform: translateZ(0); }
  50% { filter: brightness(1.2); transform: scale(1.03); }
}