:root {
  --optive-bg: #f0fdfa;
  --optive-surface: #ffffff;
  --optive-tone: #0284c7;
  --optive-tone-hover: #0369a1;
  --optive-ink: #0f172a;
  --optive-gradient: linear-gradient(135deg, #0284c7 0%, #0d9488 100%);
  --font-display: 'Playfair Display', serif;
  --font-body: 'Inter', sans-serif;
}

/* Preset C & Layout Rules */
.optive-raised-card {
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.05), 0 8px 10px -6px rgba(0, 0, 0, 0.03);
}

.optive-cta-btn {
  box-shadow: 0 10px 20px -5px rgba(2, 132, 199, 0.3);
}

.optive-cta-btn:hover {
  filter: brightness(1.05);
  transform: translateY(-2px);
}

/* Radio Gallery Controls */
.optive-slide {
  display: none;
  width: 100%;
  height: 100%;
}

#optive-img-1:checked ~ .optive-main-slide-box .optive-slide-1,
#optive-img-2:checked ~ .optive-main-slide-box .optive-slide-2,
#optive-img-3:checked ~ .optive-main-slide-box .optive-slide-3,
#optive-img-4:checked ~ .optive-main-slide-box .optive-slide-4 {
  display: block;
}

/* Thumbnail opacity control (Preset C: opacity 0.5 when inactive) */
.optive-thumb {
  opacity: 0.5;
  transition: all 0.2s ease-in-out;
  border-color: #e2e8f0;
}

#optive-img-1:checked ~ div .optive-thumb-1,
#optive-img-2:checked ~ div .optive-thumb-2,
#optive-img-3:checked ~ div .optive-thumb-3,
#optive-img-4:checked ~ div .optive-thumb-4 {
  opacity: 1;
  border-color: var(--optive-tone);
  box-shadow: 0 0 0 2px rgba(2, 132, 199, 0.2);
}