@keyframes brief-invalid-pulse {
  0%, 100% { box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.22); }
  50% { box-shadow: 0 0 0 7px rgba(239, 68, 68, 0.1); }
}

[data-brief-invalid="true"] {
  border-color: #ef4444 !important;
  background-color: rgba(254, 242, 242, 0.96) !important;
  outline: 2px solid rgba(239, 68, 68, 0.38) !important;
  outline-offset: 2px;
  animation: brief-invalid-pulse 1.15s ease-in-out 2;
}

@media (prefers-reduced-motion: reduce) {
  [data-brief-invalid="true"] { animation: none; }
}