/* ===== Reset & Base ===== */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --bg-dark: #ffffff;
    --bg-card: #f5f5f7;
    --bg-glass: rgba(0, 0, 0, 0.04);
    --border-glass: rgba(0, 0, 0, 0.1);
    --text-primary: #1d1d1f;
    --text-muted: #6e6e73;
    --accent: #7c5cfc;
    --accent-glow: rgba(124, 92, 252, 0.25);
    --folder-accent: #0071e3;
    --radius: 12px;
    --transition: .25s cubic-bezier(.4, 0, .2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ===== Top Navigation / Tabs ===== */
.top-bar {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-glass);
    padding: 0 24px;
    box-shadow: 0 1px 8px rgba(0, 0, 0, .08);
}

.top-bar-inner {
    max-width: 1100px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    gap: 4px;
    overflow-x: auto;
    scrollbar-width: none;
    -ms-overflow-style: none;
    padding: 10px 0;
}

.top-bar-inner::-webkit-scrollbar {
    display: none;
}

.tab-btn {
    flex-shrink: 0;
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-muted);
    padding: 10px 22px;
    border-radius: 999px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
    letter-spacing: .3px;
}

.tab-btn:hover {
    color: var(--text-primary);
    background: var(--bg-glass);
    border-color: var(--border-glass);
}

.tab-btn.active {
    color: #fff;
    background: linear-gradient(135deg, var(--accent), #9b7cfc);
    border-color: transparent;
    box-shadow: 0 0 18px var(--accent-glow);
}

/* ===== Breadcrumb ===== */
.breadcrumb-bar {
    max-width: 1100px;
    margin: 16px auto 0;
    padding: 0 24px;
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 4px;
    font-size: 13px;
    color: var(--text-muted);
    min-height: 24px;
}

.breadcrumb-bar span {
    cursor: pointer;
    transition: color var(--transition);
}

.breadcrumb-bar span:hover {
    color: var(--accent);
}

.breadcrumb-bar .sep {
    margin: 0 2px;
    opacity: .4;
    cursor: default;
}

/* ===== Container ===== */
.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 20px 24px 60px;
}

/* ===== Folder Grid ===== */
.folder-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 14px;
    margin-bottom: 24px;
}

.folder-card {
    display: flex;
    align-items: center;
    gap: 10px;
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius);
    padding: 14px 16px;
    cursor: pointer;
    transition: var(--transition);
}

.folder-card:hover {
    background: var(--bg-glass);
    border-color: var(--folder-accent);
    transform: translateY(-2px);
    box-shadow: 0 6px 24px rgba(0, 113, 227, .12);
}

.folder-icon {
    font-size: 26px;
    flex-shrink: 0;
}

.folder-name {
    font-size: 13px;
    font-weight: 500;
    overflow: hidden;
    text-overflow: ellipsis;
    word-break: break-all;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    line-clamp: 2;
    -webkit-box-orient: vertical;
}

/* ===== Lazy placeholder ===== */
.lazy-placeholder {
    min-height: 200px;
    background: linear-gradient(110deg, var(--bg-card) 30%, var(--bg-glass) 50%, var(--bg-card) 70%);
    background-size: 200% 100%;
    animation: shimmer 1.4s ease-in-out infinite;
}

@keyframes shimmer {
    to {
        background-position: -200% 0;
    }
}

/* ===== Image List ===== */
.image-list {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.image-list img {
    /* 使用 vw (viewport width) 保证无论父容器多宽，图片都是屏幕宽度的 70% */
    width: 70vw;
    height: auto;
    border-radius: 10px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, .1);
    display: block;
    transition: var(--transition);
    background: var(--bg-card);
}

.image-list img:hover {
    box-shadow: 0 8px 30px rgba(124, 92, 252, .15);
    transform: scale(1.005);
}

/* ===== Loading Spinner ===== */
.loader {
    display: flex;
    justify-content: center;
    padding: 60px 0;
}

.spinner {
    width: 42px;
    height: 42px;
    border: 3px solid var(--border-glass);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin .75s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

/* ===== Section Title ===== */
.section-title {
    font-size: 15px;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 14px;
    letter-spacing: .5px;
    text-transform: uppercase;
}

/* ===== Empty State ===== */
.empty-state {
    text-align: center;
    padding: 60px 0;
    color: var(--text-muted);
    font-size: 14px;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .image-list img {
        width: 92%;
    }

    .folder-grid {
        grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    }

    .top-bar {
        padding: 0 12px;
    }

    .container {
        padding: 14px 12px 40px;
    }
}