.customizer-card {
  position: relative;
  isolation: isolate;
}

.customizer-card.custom-mode {
  box-shadow: 0 16px 35px rgba(50, 52, 89, .15);
}

.customizer-card.custom-mode::before {
  content: "";
  position: absolute;
  z-index: -1;
  inset: -5px;
  border-radius: 22px;
  background: linear-gradient(90deg, #8275d9, #61d7ee, #c9f86f, #f0a56f, #e47796, #8275d9);
  background-size: 300% 100%;
  animation: custom-rainbow-border 3s linear infinite;
}

@keyframes custom-rainbow-border {
  to { background-position: 300% 0; }
}

@media (prefers-reduced-motion: reduce) {
  .customizer-card.custom-mode::before {
    animation: none;
  }
}