:root {
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --header-bg: #f8f8f8;
    --border-color: #e0e0e0;
    --thumb-bg: #f0f0f0;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #121212;
        --text-color: #e0e0e0;
        --header-bg: #1e1e1e;
        --border-color: #333;
        --thumb-bg: #2a2a2a;
    }
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    margin: 0;
    background-color: var(--bg-color);
    color: var(--text-color);
    padding-top: env(safe-area-inset-top);
    padding-left: env(safe-area-inset-left);
    padding-right: env(safe-area-inset-right);
}

header {
    background-color: var(--header-bg);
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
    text-align: center;
    position: sticky;
    top: 0;
    z-index: 10;
}

h1, h2 {
    margin: 0;
}

main {
    padding: 1rem;
}

.gallery-folder {
    margin-bottom: 2rem;
}

.gallery-folder h2 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    padding-left: 0.5rem;
    border-left: 3px solid var(--text-color);
}

.thumbnail-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
    gap: 5px;
}

.thumbnail-grid a {
    display: block;
    aspect-ratio: 1 / 1;
    background-color: var(--thumb-bg);
}

.thumbnail-grid img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: opacity 0.3s;
}

/* Viewer Styles */
.viewer-body {
    background-color: #000;
}

#viewer {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    touch-action: manipulation; /* for pinch-zoom */
}

#current-image {
    max-width: 100vw;
    max-height: 100vh;
    object-fit: contain;
    transition: opacity 0.2s ease-in-out;
}

.close-button {
    position: absolute;
    top: calc(1rem + env(safe-area-inset-top));
    right: calc(1rem + env(safe-area-inset-right));
    font-size: 2rem;
    color: white;
    cursor: pointer;
    background: rgba(0,0,0,0.5);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    display: flex;
    justify-content: center;
    align-items: center;
    line-height: 44px;
    text-shadow: 0 0 5px black;
}

.loading, .loader {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    color: #ccc;
}

.loader {
    border: 4px solid #f3f3f3;
    border-top: 4px solid #3498db;
    border-radius: 50%;
    width: 40px;
    height: 40px;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}