/* Clean-White Design System Variables */
:root {
  --primary: #4338ca;
  --secondary: #eef2ff;
  --accent: #f97316;
  --text: #1e1b4b;
  --bg: #fafafa;
}

/* Base reset and settings */
body {
  font-family: 'Inter', sans-serif;
  background: #fff;
  color: #111;
  font-size: clamp(14px, 4vw, 16px);
  line-height: 1.5;
  overflow-x: hidden;
}

section {
  padding: 48px 16px;
}

@media (min-width: 768px) {
  section {
    padding: 64px 16px;
  }
}

.card {
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  box-shadow: none;
}

.btn {
  border-radius: 6px;
  font-weight: 600;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

h1, h2 {
  font-weight: 700;
}

h1 {
  font-size: clamp(20px, 4.5vw, 28px);
}

h2 {
  font-size: clamp(22px, 5vw, 32px);
}

/* Screen Reader Only Utility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Pure CSS Gallery Rules */
.gallery-main {
  position: relative;
  width: 100%;
  padding-bottom: 100%; /* Strict aspect ratio height */
  overflow: hidden;
}

.slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  z-index: 1;
  transition: opacity 0.3s ease-in-out;
}

/* Active slide states based on radio inputs */
#img-1:checked ~ .gallery-main .slide-1,
#img-2:checked ~ .gallery-main .slide-2,
#img-3:checked ~ .gallery-main .slide-3,
#img-4:checked ~ .gallery-main .slide-4 {
  opacity: 1;
  z-index: 10;
}

/* Active thumbnail outline based on radio inputs */
#img-1:checked ~ .thumbnails label[for="img-1"],
#img-2:checked ~ .thumbnails label[for="img-2"],
#img-3:checked ~ .thumbnails label[for="img-3"],
#img-4:checked ~ .thumbnails label[for="img-4"] {
  border-color: var(--primary);
  box-shadow: 0 0 0 1px var(--primary);
}