/* Checkerboard pattern background for transparent image preview */
.checkerboard {
  background-color: #0f172a;
  background-image:
    linear-gradient(45deg, rgba(255,255,255,0.08) 25%, transparent 25%),
    linear-gradient(-45deg, rgba(255,255,255,0.08) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, rgba(255,255,255,0.08) 75%),
    linear-gradient(-45deg, transparent 75%, rgba(255,255,255,0.08) 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0;
}

#dropZone.dragover {
  border-color: rgb(129 140 248 / 0.9);
  background-color: rgb(15 23 42 / 0.85);
  box-shadow: 0 0 0 4px rgb(99 102 241 / 0.15) inset;
}

.bg-swatch.active {
  outline: 2px solid rgb(129 140 248);
  outline-offset: 2px;
}

/* Smooth section transitions */
section {
  transition: opacity 300ms ease, transform 300ms ease;
}
section.is-hidden {
  opacity: 0;
  transform: translateY(8px);
  pointer-events: none;
}