* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --bg: #f5f5f5;
    --card-bg: white;
    --text: #333;
    --text-muted: #888;
    --accent: #4CAF50;
    --shadow: 0 2px 8px rgba(0,0,0,0.1);
    --radius: 12px;
    --transition: 0.3s ease;
}

body {
    font-family: system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    min-height: 100dvh;
    overflow-x: hidden;
}

#app {
    min-height: 100vh;
    min-height: 100dvh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 1rem;
    position: relative;
}

header h1 {
    font-size: 1.25rem;
    font-weight: 600;
}

.zoom-btn {
    position: absolute;
    right: 1rem;
    background: var(--card-bg);
    border: none;
    border-radius: 8px;
    padding: 0.5rem;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: transform var(--transition);
}

.zoom-btn:hover {
    transform: scale(1.05);
}

.zoom-btn[hidden] {
    display: none;
}

/* Year View */
.year-view {
    flex: 1;
    padding: 0.5rem;
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    grid-template-rows: repeat(5, 1fr);
    gap: 0.5rem;
    opacity: 1;
    transition: opacity var(--transition);
}

.year-view[hidden] {
    display: none;
}

.year-month {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 0.5rem;
    box-shadow: var(--shadow);
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
}

.year-month:active {
    transform: scale(0.98);
}

.year-month.inactive {
    opacity: 0.4;
    cursor: default;
}

.year-month-name {
    font-size: 0.7rem;
    font-weight: 600;
    text-align: center;
    margin-bottom: 0.25rem;
}

.year-month-days {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 1px;
}

.year-day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.45rem;
    color: var(--text-muted);
}

.year-day.empty {
    visibility: hidden;
}

.year-day.has-photo {
    background: var(--accent);
    border-radius: 50%;
    color: white;
    font-weight: 600;
}

/* Month View */
.month-view {
    flex: 1;
    display: flex;
    flex-direction: column;
    padding: 0 1rem 1rem;
    opacity: 1;
    transition: opacity var(--transition);
}

.month-view[hidden] {
    display: none;
}

.month-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.5rem 0 1rem;
}

.month-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
}

.nav-btn {
    background: var(--card-bg);
    border: none;
    border-radius: 8px;
    padding: 0.5rem 1rem;
    font-size: 1rem;
    cursor: pointer;
    box-shadow: var(--shadow);
    transition: transform var(--transition), opacity var(--transition);
}

.nav-btn:active {
    transform: scale(0.95);
}

.nav-btn:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.month-grid {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.day-headers {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 4px;
    margin-bottom: 8px;
}

.day-header {
    text-align: center;
    font-size: 0.75rem;
    color: var(--text-muted);
    padding: 4px 0;
}

.days-grid {
    flex: 1;
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 2px;
}

.day {
    aspect-ratio: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.85rem;
    color: var(--text-muted);
    position: relative;
    overflow: hidden;
}

.day.empty {
    visibility: hidden;
}

.day.has-photo {
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
}

.day.has-photo img {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.day.has-photo:active {
    transform: scale(0.95);
}

/* Photo View */
.photo-view {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.95);
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    opacity: 1;
    transition: opacity var(--transition);
}

.photo-view[hidden] {
    display: none;
}

.close-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    font-size: 2rem;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background var(--transition);
    z-index: 10;
}

.close-btn:hover {
    background: rgba(255,255,255,0.3);
}

.photo-container {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    padding: 1rem;
    touch-action: pan-y;
}

.photo-container img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
    transition: transform var(--transition), opacity var(--transition);
}

.photo-info {
    padding: 1rem;
    text-align: center;
    color: white;
}

.photo-info p {
    font-size: 1rem;
}

.photo-nav {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255,255,255,0.2);
    border: none;
    color: white;
    font-size: 1.5rem;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: background var(--transition), opacity var(--transition);
}

.photo-nav:hover {
    background: rgba(255,255,255,0.3);
}

.photo-nav:disabled {
    opacity: 0.2;
    cursor: not-allowed;
}

.photo-nav.prev {
    left: 1rem;
}

.photo-nav.next {
    right: 1rem;
}

/* Desktop enhancements */
@media (min-width: 600px) {
    header h1 {
        font-size: 1.5rem;
    }

    .year-view {
        padding: 1rem;
        gap: 1rem;
        max-width: 700px;
        margin: 0 auto;
        grid-template-columns: repeat(5, 1fr);
        grid-template-rows: repeat(2, 1fr);
    }

    .year-month {
        padding: 0.75rem;
    }

    .year-month-name {
        font-size: 0.8rem;
    }

    .year-day {
        font-size: 0.55rem;
    }

    .month-view {
        max-width: 500px;
        margin: 0 auto;
        padding: 0 2rem 2rem;
    }

    .month-header h2 {
        font-size: 1.25rem;
    }

    .day {
        font-size: 1rem;
    }

    .day.has-photo:hover {
        transform: scale(1.05);
        z-index: 5;
    }

    .photo-nav {
        width: 56px;
        height: 56px;
        font-size: 2rem;
    }

    .photo-nav.prev {
        left: 2rem;
    }

    .photo-nav.next {
        right: 2rem;
    }
}