:root {
    --bg-body: #f9f9f9;
    --bg-header: rgba(255, 255, 255, 0.85);
    --bg-card: #fff;
    --bg-photo-placeholder: #efefef;
    --text-main: #333;
    --text-muted: #666;
    --text-light: #999;
    --border-color: #eee;
    --border-strong: #ddd;
    --shadow-sm: rgba(0, 0, 0, 0.05);
    --shadow-md: rgba(0, 0, 0, 0.1);
    --hover-overlay: rgba(0, 0, 0, 0.05);
}

[data-theme="dark"] {
    --bg-body: #121212;
    --bg-header: rgba(26, 26, 26, 0.85);
    --bg-card: #1e1e1e;
    --bg-photo-placeholder: #2a2a2a;
    --text-main: #e0e0e0;
    --text-muted: #aaa;
    --text-light: #777;
    --border-color: #333;
    --border-strong: #444;
    --shadow-sm: rgba(0, 0, 0, 0.3);
    --shadow-md: rgba(0, 0, 0, 0.5);
    --hover-overlay: rgba(255, 255, 255, 0.05);
}

body {
    font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--bg-body);
    color: var(--text-main);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    padding: 1.5rem 2rem;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
    background-color: var(--bg-header);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: background-color 0.3s ease, border-color 0.3s ease;
}

header h1 {
    margin: 0;
    font-weight: 300;
    letter-spacing: 0.1em;
    font-size: 1.5rem;
}

header nav a {
    text-decoration: none;
    color: var(--text-main);
    margin: 0 1rem;
    opacity: 0.7;
    transition: opacity 0.2s;
    position: relative;
}

header nav a:hover,
header nav a.active {
    opacity: 1;
}

header nav a.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 100%;
    height: 2px;
    background-color: var(--text-main);
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.month-group {
    margin-bottom: 4rem;
}

.month-header {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    font-weight: 400;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--border-strong);
    padding-bottom: 0.5rem;
    color: var(--text-main);
}

.photo-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.photo-item,
.event-item {
    background: var(--bg-card);
    box-shadow: 0 2px 5px var(--shadow-sm);
    border-radius: 4px;
    overflow: hidden;
    transition: transform 0.2s, background-color 0.3s ease, box-shadow 0.3s ease;
    text-decoration: none;
    color: inherit;
    display: block;
}

.photo-item:hover,
.event-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 5px 15px var(--shadow-md);
}

.photo-container {
    padding-bottom: 100%;
    /* Square aspect ratio 1:1 */
    position: relative;
    background-color: var(--bg-photo-placeholder);
    overflow: hidden;
}

.photo-container img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
    transition: transform 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.photo-item:hover .photo-container img,
.event-item:hover .photo-container img {
    transform: scale(1.05);
}

.photo-info {
    padding: 1rem;
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
}

.photo-date {
    font-size: 0.85rem;
    color: #888;
    margin-bottom: 0;
    flex-shrink: 0;
}

.photo-title {
    font-weight: 500;
    font-size: 1rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Single Photo Page */
.single-photo-container {
    text-align: center;
    padding: 2rem 0;
}

.single-photo-img {
    max-width: 100%;
    max-height: 80vh;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    border-radius: 4px;
}

.back-link {
    display: inline-block;
    margin-top: 2rem;
    text-decoration: none;
    color: #666;
    border: 1px solid #ccc;
    padding: 0.5rem 1rem;
    border-radius: 4px;
    transition: all 0.2s;
}

.back-link:hover {
    background-color: #333;
    color: #fff;
    border-color: #333;
}

@media (max-width: 600px) {
    .photo-grid {
        grid-template-columns: 1fr;
    }

    main {
        padding: 1rem;
    }

    header h1 {
        font-size: 1.25rem;
    }
}

/* On This Day - Horizontal Scroll */
.otd-grid {
    display: grid;
    /* Responsive columns: auto-fit ensures it centers and wraps nicely */
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    padding-bottom: 0;
    /* No longer scrolling horizontally, so no scrollbar space needed */
}

/* Remove scrollbar styles for otd-grid as we are moving to grid */
.otd-grid::-webkit-scrollbar {
    display: none;
}

/* Ensure OTD photo items behave like regular grid items */
.otd-grid .photo-item {
    min-width: 0;
    /* Reset min-width overrides */
    max-width: none;
    /* Reset max-width overrides */
    flex: none;
}


.otd-grid::-webkit-scrollbar-track {
    display: none;
}

.otd-grid::-webkit-scrollbar-thumb {
    display: none;
}

.otd-grid::-webkit-scrollbar-thumb:hover {
    display: none;
}

/* Theme Switcher */
.theme-switch-wrapper {
    display: flex;
    align-items: center;
}

.theme-switch {
    display: inline-block;
    height: 24px;
    position: relative;
    width: 48px;
}

.theme-switch input {
    display: none;
}

.slider {
    background-color: #ccc;
    bottom: 0;
    cursor: pointer;
    left: 0;
    position: absolute;
    right: 0;
    top: 0;
    transition: .4s;
}

.slider:before {
    background-color: #fff;
    bottom: 3px;
    content: "";
    height: 18px;
    left: 3px;
    position: absolute;
    transition: .4s;
    width: 18px;
}

input:checked+.slider {
    background-color: #2196F3;
}

input:checked+.slider:before {
    transform: translateX(24px);
}

.slider.round {
    border-radius: 24px;
}

.slider.round:before {
    border-radius: 50%;
}

/* Fluid Gallery Styles (Row Order) */
.photo-grid.fluid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
    align-items: start;
    /* Prevents stretching to fill row height */
}

.photo-grid.fluid .photo-item {
    display: block;
    width: 100%;
    margin-bottom: 0;
    transition: transform 0.2s, box-shadow 0.3s ease;
}

.photo-grid.fluid .photo-item:hover {
    transform: translateY(-3px);
}

.photo-grid.fluid .photo-container {
    padding-bottom: 0;
    height: auto;
    background-color: transparent;
}

.photo-grid.fluid .photo-container img {
    position: relative;
    width: 100%;
    height: auto;
    display: block;
}

@media (max-width: 900px) {
    .photo-grid.fluid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 600px) {
    .photo-grid.fluid {
        grid-template-columns: 1fr;
    }
}