/* CSS Variables & Clean-White Theme */
:root {
    --primary: #0694a2;
    --secondary: #e6fffa;
    --accent: #f59e0b;
    --text: #05505c;
    --bg: #f8fffe;
}

/* Base Typography Configuration */
body {
    background: #fff;
    color: #111;
    font-size: clamp(14px, 4vw, 16px);
}

section {
    padding: 64px 16px;
}

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

.btn {
    border-radius: 6px;
    font-weight: 600;
}

h1 {
    font-size: clamp(22px, 5vw, 36px);
    font-weight: 700;
}

h2 {
    font-size: clamp(18px, 4.5vw, 28px);
    font-weight: 700;
}

/* Screen Reader Only Utility (Strictly Required for Gallery Inputs) */
.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;
}

/* Gallery Layout & CSS Logic */
.gallery-main {
    position: relative;
    width: 100%;
    padding-bottom: 100%; /* Keeps aspect ratio 1:1 without JS */
    overflow: hidden;
}

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

.slide img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Thumbnails Grid */
.thumbnails {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 8px;
    margin-top: 12px;
}

.thumbnails label {
    aspect-ratio: 1;
    cursor: pointer;
    border: 2px solid transparent;
    border-radius: 6px;
    overflow: hidden;
    transition: border-color 0.2s ease-in-out;
}

.thumbnails label img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Active Slide & Thumbnail States based on Checked Radios */
#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;
}

#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);
}