/* Admin: Library Links badges */
.link-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.5rem;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  margin-right: 0.5rem;
  margin-bottom: 0.25rem;
}
.link-remove-btn {
  background: none;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0 0.2rem;
  font-size: 1rem;
  line-height: 1;
}
.link-remove-btn:hover { color: var(--danger); }
.library-links-cell { min-width: 12rem; }
.link-add-btn { margin-left: 0.25rem !important; }

/* ===== CSS Variables ===== */
:root {
    /* Light Theme */
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --bg-tertiary: #e9ecef;
    --text-primary: #212529;
    --text-secondary: #6c757d;
    --text-muted: #adb5bd;
    --border-color: #dee2e6;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.1);
    
    /* Colors */
    --primary: #0d6efd;
    --primary-hover: #0b5ed7;
    --secondary: #6c757d;
    --success: #198754;
    --danger: #dc3545;
    --warning: #ffc107;
    --info: #0dcaf0;
    
    /* Sidebar */
    --sidebar-width: 260px;
    --sidebar-bg: #2c3e50;
    --sidebar-text: #ecf0f1;
    --sidebar-hover: #34495e;
    
    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
}

[data-theme="dark"],
body.theme-dark {
    /* Dark Theme */
    --bg-primary: #1a1d29;
    --bg-secondary: #252936;
    --bg-tertiary: #2f3442;
    --text-primary: #e4e6eb;
    --text-secondary: #b0b3b8;
    --text-muted: #8a8d91;
    --border-color: #3a3f4b;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 6px rgba(0,0,0,0.3);
    --shadow-lg: 0 10px 15px rgba(0,0,0,0.3);
    
    --sidebar-bg: #1e2329;
    --sidebar-text: #e4e6eb;
    --sidebar-hover: #2a2f3a;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* ===== Sidebar ===== */
.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: var(--sidebar-width);
    height: 100vh;
    background: var(--sidebar-bg);
    color: var(--sidebar-text);
    display: flex;
    flex-direction: column;
    z-index: 1000;
    transition: transform 0.3s ease;
    box-shadow: var(--shadow-lg);
}

.sidebar-header {
    padding: var(--spacing-lg);
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.logo { display: flex; align-items: center; gap: var(--spacing-sm); font-size: 1.25rem; font-weight: 700; }
.logo i { font-size: 1.5rem; color: var(--primary); }

.sidebar-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--sidebar-text);
    font-size: 1.25rem;
    cursor: pointer;
    padding: var(--spacing-sm);
}

.sidebar-nav { flex: 1; padding: var(--spacing-md); overflow-y: auto; }

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    color: var(--sidebar-text);
    text-decoration: none;
    border-radius: var(--radius-md);
    margin-bottom: var(--spacing-xs);
    transition: all 0.2s ease;
    position: relative;
}

.nav-item:hover { background: var(--sidebar-hover); }
.nav-item.active { background: var(--primary); color: white; }
.nav-item i { width: 20px; text-align: center; }

.badge {
    margin-left: auto;
    background: rgba(255,255,255,0.2);
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
}

.nav-item.active .badge { background: rgba(255,255,255,0.3); }

.sidebar-footer {
    padding: var(--spacing-md);
    border-top: 1px solid rgba(255,255,255,0.1);
}

.theme-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--sidebar-hover);
    border: none;
    color: var(--sidebar-text);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: background 0.2s ease;
}

.theme-toggle:hover { background: rgba(255,255,255,0.1); }

/* ===== Main Content ===== */
.main-content {
    margin-left: var(--sidebar-width);
    padding: var(--spacing-xl);
    min-height: 100vh;
    transition: margin-left 0.3s ease;
}

/* Nút quay lại trang khách - luôn hiển thị rõ ràng */
.admin-topbar {
    display: flex;
    align-items: center;
    margin: calc(-1 * var(--spacing-xl)) calc(-1 * var(--spacing-xl)) var(--spacing-lg) calc(-1 * var(--spacing-xl));
    padding: 0.75rem var(--spacing-xl);
    background: linear-gradient(135deg, rgba(13, 110, 253, 0.1), rgba(13, 110, 253, 0.05));
    border-bottom: 1px solid rgba(13, 110, 253, 0.2);
}

.btn-back-public {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.95rem;
    border-radius: var(--radius-md);
    transition: all 0.2s ease;
}

.btn-back-public:hover {
    background: rgba(13, 110, 253, 0.1);
    color: var(--primary-hover);
}

.nav-item-public {
    background: rgba(13, 110, 253, 0.15) !important;
    border: 1px solid rgba(13, 110, 253, 0.3);
}

.nav-item-public:hover {
    background: rgba(13, 110, 253, 0.25) !important;
}

.page { display: none; }
.page.active { display: block; animation: fadeIn 0.3s ease; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.page-header {
    margin-bottom: var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: var(--spacing-md);
}

.page-header h1 { font-size: 2rem; font-weight: 700; color: var(--text-primary); }
.subtitle { color: var(--text-secondary); margin-top: var(--spacing-xs); }

/* ===== Buttons ===== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-lg);
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    text-decoration: none;
}

.btn-primary { background: var(--primary); color: white; }
.btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-secondary { background: var(--secondary); color: white; }
.btn-secondary:hover { background: #5a6268; }
.btn-danger { background: var(--danger); color: white; }
.btn-danger:hover { background: #bb2d3b; }
.btn-sm { padding: var(--spacing-xs) var(--spacing-md); font-size: 0.75rem; }

/* ===== Cards ===== */
.card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    transition: box-shadow 0.2s ease;
}

.card:hover { box-shadow: var(--shadow-md); }

.card-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.card-header h2 { font-size: 1.25rem; font-weight: 600; }
.card-body { padding: var(--spacing-lg); }

/* ===== Stats Grid ===== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-xl);
}

.stat-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }

.stat-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
}

.stat-icon.blue { background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); }
.stat-icon.green { background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%); }
.stat-icon.orange { background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%); }
.stat-icon.purple { background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%); }

.stat-info h3 { font-size: 2rem; font-weight: 700; color: var(--text-primary); }
.stat-info p { color: var(--text-secondary); font-size: 0.875rem; }

/* ===== Dashboard Grid ===== */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-lg);
}

.list-container { min-height: 200px; }
.empty-state { text-align: center; color: var(--text-muted); padding: var(--spacing-xl); }

/* ===== Filter Bar ===== */
.filter-bar {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.search-box {
    flex: 1;
    min-width: 250px;
    position: relative;
}

.search-box i {
    position: absolute;
    left: var(--spacing-md);
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

.search-box input {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md) var(--spacing-sm) 2.5rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.875rem;
}

.search-box input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(13, 110, 253, 0.1);
}

/* ===== Apps Grid ===== */
.apps-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: var(--spacing-lg);
}

.app-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease;
    cursor: pointer;
}

.app-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); }

.app-card-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.app-icon {
    width: 50px;
    height: 50px;
    border-radius: var(--radius-md);
    background: var(--bg-tertiary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    flex-shrink: 0;
}

.app-icon img { width: 100%; height: 100%; object-fit: cover; border-radius: var(--radius-md); }

.app-info h3 { font-size: 1.125rem; font-weight: 600; margin-bottom: var(--spacing-xs); }
.app-info .app-category { font-size: 0.75rem; color: var(--text-secondary); text-transform: uppercase; }

.app-description {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.app-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

.app-version { font-size: 0.75rem; color: var(--text-muted); font-family: 'Courier New', monospace; }

.app-status { padding: 4px 12px; border-radius: 12px; font-size: 0.75rem; font-weight: 600; }
.app-status.active { background: rgba(25, 135, 84, 0.1); color: var(--success); }
.app-status.development { background: rgba(255, 193, 7, 0.1); color: #ff9800; }
.app-status.maintenance { background: rgba(13, 110, 253, 0.1); color: var(--primary); }
.app-status.deprecated { background: rgba(220, 53, 69, 0.1); color: var(--danger); }

.app-actions { display: flex; gap: var(--spacing-sm); }

.btn-icon {
    width: 32px;
    height: 32px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-sm);
    background: var(--bg-tertiary);
    border: none;
    cursor: pointer;
    color: var(--text-secondary);
    transition: all 0.2s ease;
}

.btn-icon:hover { background: var(--primary); color: white; }

/* ===== Articles List ===== */
.articles-list { display: flex; flex-direction: column; gap: var(--spacing-md); }

.article-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease;
    display: flex;
    gap: var(--spacing-lg);
}

.article-card:hover { box-shadow: var(--shadow-md); transform: translateX(4px); }

.article-image {
    width: 120px;
    height: 120px;
    border-radius: var(--radius-md);
    object-fit: cover;
    flex-shrink: 0;
    background: var(--bg-tertiary);
}

.article-content { flex: 1; }

.article-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-sm);
}

.article-title { font-size: 1.25rem; font-weight: 600; color: var(--text-primary); margin-bottom: var(--spacing-xs); }

.article-meta {
    display: flex;
    gap: var(--spacing-md);
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-sm);
}

.article-excerpt {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: var(--spacing-md);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.article-tags { display: flex; gap: var(--spacing-xs); flex-wrap: wrap; }
.tag { padding: 4px 8px; background: var(--bg-tertiary); border-radius: var(--radius-sm); font-size: 0.75rem; color: var(--text-secondary); }

/* ===== Versions Timeline ===== */
.versions-timeline { position: relative; padding-left: var(--spacing-xl); }
.versions-timeline::before {
    content: '';
    position: absolute;
    left: 10px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--border-color);
}

.version-item {
    position: relative;
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    transition: all 0.2s ease;
}

.version-item:hover { box-shadow: var(--shadow-md); }

.version-item::before {
    content: '';
    position: absolute;
    left: -26px;
    top: 24px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--primary);
    border: 3px solid var(--bg-secondary);
}

.version-header { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: var(--spacing-md); }
.version-info h3 { font-size: 1.125rem; font-weight: 600; margin-bottom: var(--spacing-xs); }
.version-info .version-app { font-size: 0.875rem; color: var(--text-secondary); }

.version-badge { padding: 4px 12px; border-radius: 12px; font-size: 0.75rem; font-weight: 600; }
.version-badge.major { background: rgba(220, 53, 69, 0.1); color: var(--danger); }
.version-badge.minor { background: rgba(255, 193, 7, 0.1); color: #ff9800; }
.version-badge.patch { background: rgba(13, 110, 253, 0.1); color: var(--primary); }

.version-notes {
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.6;
    white-space: pre-wrap;
    margin-bottom: var(--spacing-md);
}

.version-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-md);
    border-top: 1px solid var(--border-color);
}

.version-date { font-size: 0.875rem; color: var(--text-muted); }

/* ===== Forms ===== */
.form-group { margin-bottom: var(--spacing-lg); }
.form-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: var(--spacing-md); }

label { display: block; margin-bottom: var(--spacing-xs); font-weight: 500; color: var(--text-primary); font-size: 0.875rem; }

.form-control {
    width: 100%;
    padding: var(--spacing-sm) var(--spacing-md);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-primary);
    color: var(--text-primary);
    font-size: 0.875rem;
    transition: all 0.2s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(13, 110, 253, 0.1);
}

textarea.form-control { resize: vertical; min-height: 100px; }

textarea.form-control.textarea-description {
    min-height: 20rem;
    max-height: 85vh;
    resize: both;
    overflow-y: auto;
    width: 100%;
    min-width: 100%;
}

.link-item textarea.form-control { min-height: 3.5rem; resize: both; max-height: 20rem; }
.video-item textarea.form-control.video-desc-input { min-height: 5rem; resize: both; max-height: 50vh; overflow-y: auto; }
select.form-control { cursor: pointer; }

.form-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border-color);
}

.form-group-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: var(--spacing-sm); }
.form-group-header label { margin-bottom: 0; }
.btn-sm { padding: var(--spacing-xs) var(--spacing-sm); font-size: 0.875rem; }

/* Links Container */
.links-container, .videos-container {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
    margin-top: var(--spacing-md);
}

.link-item, .video-item {
    display: flex;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    align-items: start;
}

.link-item-content, .video-item-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.link-item input, .video-item input { width: 100%; }

.video-item-label {
    display: block;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 0.25rem;
    color: var(--text-primary);
}

.link-item-actions, .video-item-actions { display: flex; gap: var(--spacing-xs); }
.link-item-actions button, .video-item-actions button { padding: var(--spacing-xs) var(--spacing-sm); min-width: auto; }
.form-text { display: block; margin-top: var(--spacing-xs); font-size: 0.875rem; color: var(--text-secondary); }

/* ===== Modal ===== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-lg);
    overflow-y: auto;
}

.modal.active { display: flex; animation: fadeIn 0.2s ease; }

.modal-content {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    width: 100%;
    max-width: 600px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s ease;
}

.modal-large { max-width: 900px; }

.modal-content.modal-fullscreen {
    position: fixed;
    left: 0;
    top: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
    max-width: none;
    max-height: none;
    border-radius: 0;
    margin: 0;
    padding: 0;
}

.modal-content.modal-fullscreen .modal-body { flex: 1; min-height: 0; overflow-y: auto; }

@keyframes slideUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

.modal-header {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.modal-header h2 { font-size: 1.5rem; font-weight: 600; }

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: var(--spacing-xs);
    transition: color 0.2s ease;
}

.modal-close:hover { color: var(--text-primary); }
.modal-body { padding: var(--spacing-lg); overflow-y: auto; }

/* ===== Settings ===== */
.settings-container { display: flex; flex-direction: column; gap: var(--spacing-lg); }

.setting-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-color);
}

.setting-item:last-child { border-bottom: none; }
.setting-info h3 { font-size: 1rem; font-weight: 600; margin-bottom: var(--spacing-xs); }
.setting-info p { font-size: 0.875rem; color: var(--text-secondary); }

.switch { position: relative; display: inline-block; width: 50px; height: 26px; }
.switch input { opacity: 0; width: 0; height: 0; }
.slider {
    position: absolute;
    cursor: pointer;
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: var(--bg-tertiary);
    transition: 0.3s;
    border-radius: 26px;
}
.slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: 0.3s;
    border-radius: 50%;
}
input:checked + .slider { background-color: var(--primary); }
input:checked + .slider:before { transform: translateX(24px); }

/* ===== Analytics ===== */
.analytics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-lg);
}

/* ===== Responsive - tối ưu mọi thiết bị ===== */
@media (max-width: 992px) {
    .main-content { padding: var(--spacing-md); }
    .dashboard-grid { grid-template-columns: 1fr; }
    .analytics-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
    .sidebar { transform: translateX(-100%); }
    .sidebar.active { transform: translateX(0); }
    .sidebar-toggle { display: block; }
    .main-content { margin-left: 0; padding: var(--spacing-md); }
    .page-header { flex-direction: column; align-items: flex-start; }
    /* Màn hình nhỏ: 2 card 1 dòng, 4 card = 2 dòng */
    .stats-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .dashboard-grid { grid-template-columns: 1fr; }
    .apps-grid { grid-template-columns: 1fr; }
    .article-card { flex-direction: column; }
    .article-image { width: 100%; height: 200px; }
    .form-row { grid-template-columns: 1fr; }
    .modal-content { max-width: 100%; margin: var(--spacing-md); }
    .filter-bar { flex-direction: column; }
    .search-box { min-width: 100%; }
}

@media (max-width: 480px) {
    .page-header h1 { font-size: 1.5rem; }
    .stat-card { flex-direction: column; text-align: center; }
    .app-card-header { flex-direction: column; align-items: flex-start; }
}

/* Màn hình rất nhỏ: 1 card/dòng cho stats */
@media (max-width: 360px) {
    .stats-grid { grid-template-columns: 1fr; }
}

/* ===== Admin với menu trang khách (topbar) ===== */
.main-content-admin {
    margin-left: 0 !important;
    padding-top: 0 !important;
    margin-top: 56px; /* topbar height */
}

.admin-sub-nav {
    position: sticky;
    top: 56px;
    z-index: 999;
    display: flex;
    flex-wrap: wrap;
    gap: 0.25rem;
    padding: 0.75rem 1.5rem;
    background: var(--bg-card);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 1px 3px rgba(0,0,0,0.06);
}

.admin-sub-nav .nav-item {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    text-decoration: none;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s;
    background: none;
    border: none;
    cursor: pointer;
    margin: 0;
}

.admin-sub-nav .nav-item:hover {
    color: var(--accent-cpp);
    background: rgba(14, 165, 233, 0.08);
}

.admin-sub-nav .nav-item.active {
    color: var(--accent-cpp);
    background: rgba(14, 165, 233, 0.12);
}

.admin-sub-nav .nav-item .badge {
    margin-left: 0;
    background: rgba(14, 165, 233, 0.2);
    color: var(--accent-cpp);
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.75rem;
}

.admin-sub-nav .nav-item.active .badge {
    background: rgba(14, 165, 233, 0.3);
}

.admin-sub-nav .admin-settings-dropdown {
    position: relative;
    display: inline-block;
}
.admin-sub-nav .admin-settings-toggle {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    background: none;
    border: none;
    border-radius: var(--radius-md);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    font-family: inherit;
}
.admin-sub-nav .admin-settings-toggle:hover {
    color: var(--accent-cpp);
    background: rgba(14, 165, 233, 0.08);
}
.admin-sub-nav .admin-settings-dropdown.open .admin-settings-toggle,
.admin-sub-nav .admin-settings-dropdown.active .admin-settings-toggle {
    color: var(--accent-cpp);
    background: rgba(14, 165, 233, 0.12);
}
.admin-sub-nav .admin-settings-content {
    min-width: 180px;
    top: 100%;
    left: 0;
    margin-top: 0.25rem;
}
.admin-sub-nav .admin-settings-content .menu-dropdown-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    white-space: nowrap;
}

body.theme-dark .admin-sub-nav {
    background: var(--bg-card);
    border-color: var(--border);
}

@media (max-width: 768px) {
    .admin-sub-nav { top: 56px; padding: 0.5rem 1rem; }
    .main-content-admin { margin-top: 56px; }
}

/* Ẩn admin-sub-nav trên màn hình nhỏ, menu chuyển vào sidebar */
@media (max-width: 900px) {
    .admin-sub-nav {
        display: none !important;
    }
}

.hidden { display: none !important; }
.text-center { text-align: center; }
.mt-1 { margin-top: var(--spacing-sm); }
.mt-2 { margin-top: var(--spacing-md); }
.mt-3 { margin-top: var(--spacing-lg); }
.mb-1 { margin-bottom: var(--spacing-sm); }
.mb-2 { margin-bottom: var(--spacing-md); }
.mb-3 { margin-bottom: var(--spacing-lg); }
.ml-2 { margin-left: var(--spacing-md); }