/* ==========================================================================
   QA Prompt Hub - app.css
   Sprint 1: variables, reset, layout, header, forms, buttons, errors
   ========================================================================== */

:root {
    --color-bg:        #f7f8fa;
    --color-surface:   #ffffff;
    --color-border:    #e2e6ec;
    --color-text:      #1f2937;
    --color-muted:     #6b7280;
    --color-primary:   #2563eb;
    --color-primary-d: #1d4ed8;
    --color-danger:    #dc2626;
    --color-danger-bg: #fee2e2;
    --color-success:   #059669;
    --color-success-bg:#d1fae5;
    --color-warning:   #d97706;
    --color-warning-bg:#fef3c7;
    --radius-sm: 4px;
    --radius:    8px;
    --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
    --shadow:    0 4px 12px rgba(0,0,0,.08);
    --container: 960px;
}

/* Reset cơ bản */
*, *::before, *::after { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
                 "Helvetica Neue", Arial, sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

img { max-width: 100%; height: auto; display: block; }

/* Container */
.container {
    width: 100%;
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 16px;
}

/* ----- Header ----- */
.site-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
}
.header-inner {
    display: flex;
    align-items: center;
    gap: 16px;
    padding: 12px 16px;
}
.brand {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 700;
    font-size: 18px;
    color: var(--color-text);
}
.brand:hover { text-decoration: none; }
.brand-mark {
    background: var(--color-primary);
    color: #fff;
    padding: 4px 8px;
    border-radius: var(--radius-sm);
    font-size: 14px;
    letter-spacing: 1px;
}
.main-nav { flex: 1; display: flex; gap: 12px; }
.nav-link {
    color: var(--color-muted);
    padding: 6px 10px;
    border-radius: var(--radius-sm);
}
.nav-link:hover { background: var(--color-bg); text-decoration: none; }

.header-actions {
    display: flex;
    align-items: center;
    gap: 8px;
}
.inline-form { display: inline; margin: 0; }

/* ----- Buttons ----- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    padding: 8px 16px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: all .15s ease;
    text-decoration: none;
    line-height: 1;
    background: transparent;
    color: var(--color-text);
    font-family: inherit;
}
.btn:hover { text-decoration: none; }
.btn:focus-visible { outline: 2px solid var(--color-primary); outline-offset: 2px; }

.btn-primary {
    background: var(--color-primary);
    color: #fff;
    border-color: var(--color-primary);
}
.btn-primary:hover { background: var(--color-primary-d); border-color: var(--color-primary-d); }

.btn-ghost {
    background: transparent;
    color: var(--color-text);
    border-color: var(--color-border);
}
.btn-ghost:hover { background: var(--color-bg); }

.btn-link {
    background: transparent;
    color: var(--color-primary);
    padding: 8px 8px;
    border: none;
}
.btn-link:hover { text-decoration: underline; }

.btn-danger {
    background: var(--color-danger);
    color: #fff;
    border-color: var(--color-danger);
}
.btn-danger:hover { filter: brightness(0.93); }

.btn-block { display: flex; width: 100%; }

/* ----- Main / Footer ----- */
.site-main { flex: 1; padding: 32px 0; }
.site-footer {
    background: var(--color-surface);
    border-top: 1px solid var(--color-border);
    padding: 16px 0;
    color: var(--color-muted);
    font-size: 14px;
    text-align: center;
}

/* ----- Card ----- */
.card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow-sm);
}
.card + .card { margin-top: 24px; }

.card-narrow { max-width: 480px; margin: 0 auto; }
.card-medium { max-width: 640px; margin: 0 auto; }

.card h1 { margin-top: 0; margin-bottom: 8px; font-size: 22px; }
.card h2 { font-size: 18px; }

.card-subtitle { color: var(--color-muted); margin: 0 0 24px; font-size: 14px; }

/* ----- Forms ----- */
.form-group { margin-bottom: 16px; }
.form-group label {
    display: block;
    margin-bottom: 6px;
    font-weight: 500;
    font-size: 14px;
}
.form-control {
    width: 100%;
    padding: 9px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    font-family: inherit;
    background: #fff;
    color: var(--color-text);
    transition: border-color .15s, box-shadow .15s;
}
.form-control:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, .15);
}
.form-control:disabled { background: var(--color-bg); color: var(--color-muted); }
textarea.form-control { min-height: 100px; resize: vertical; }

.form-help { color: var(--color-muted); font-size: 13px; margin-top: 4px; }

.form-error {
    color: var(--color-danger);
    font-size: 13px;
    margin-top: 4px;
}
.form-control.is-invalid {
    border-color: var(--color-danger);
}
.form-control.is-invalid:focus {
    box-shadow: 0 0 0 3px rgba(220, 38, 38, .15);
}

.form-check { display: flex; align-items: flex-start; gap: 8px; }
.form-check input[type="checkbox"] { margin-top: 3px; }
.form-check label { font-weight: normal; margin: 0; }

.form-actions {
    display: flex;
    gap: 8px;
    margin-top: 24px;
    align-items: center;
    flex-wrap: wrap;
}
.form-actions .grow { flex: 1; }

/* ----- Flash messages ----- */
.flash-stack { padding-top: 16px; }
.flash {
    padding: 12px 16px;
    border-radius: var(--radius-sm);
    margin-bottom: 8px;
    font-size: 14px;
    border: 1px solid transparent;
}
.flash-success { background: var(--color-success-bg); color: var(--color-success); border-color: var(--color-success); }
.flash-error   { background: var(--color-danger-bg);  color: var(--color-danger);  border-color: var(--color-danger); }
.flash-warning { background: var(--color-warning-bg); color: var(--color-warning); border-color: var(--color-warning); }
.flash-info    { background: #dbeafe; color: var(--color-primary); border-color: var(--color-primary); }

/* ----- Error pages ----- */
.error-page {
    text-align: center;
    padding: 48px 16px;
}
.error-code {
    font-size: 96px;
    font-weight: 700;
    color: var(--color-primary);
    margin: 0;
    line-height: 1;
}
.error-title { font-size: 22px; margin: 16px 0 8px; }
.error-message { color: var(--color-muted); margin-bottom: 24px; }

/* ----- Profile ----- */
.profile-header {
    display: flex;
    gap: 24px;
    align-items: flex-start;
    flex-wrap: wrap;
    margin-bottom: 24px;
}
.profile-avatar {
    width: 96px; height: 96px;
    border-radius: 50%;
    object-fit: cover;
    background: var(--color-bg);
    border: 1px solid var(--color-border);
}
.profile-info { flex: 1; min-width: 220px; }
.profile-info h1 { margin: 0 0 4px; font-size: 24px; }
.profile-info .muted { color: var(--color-muted); font-size: 14px; }

.profile-meta {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 12px 24px;
    margin: 16px 0 24px;
    padding: 16px;
    background: var(--color-bg);
    border-radius: var(--radius-sm);
    font-size: 14px;
}
.profile-meta dt { color: var(--color-muted); margin: 0 0 2px; font-size: 13px; }
.profile-meta dd { margin: 0; font-weight: 500; word-break: break-word; }

.profile-bio { white-space: pre-wrap; word-break: break-word; }

.profile-empty {
    padding: 32px;
    text-align: center;
    color: var(--color-muted);
    background: var(--color-bg);
    border-radius: var(--radius-sm);
}

/* ----- Hero (home) ----- */
.hero {
    text-align: center;
    padding: 32px 0 48px;
}
.hero h1 { font-size: 32px; margin: 0 0 12px; }
.hero p  { color: var(--color-muted); font-size: 17px; max-width: 560px; margin: 0 auto 24px; }
.hero .actions { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* ----- Badges ----- */
.badge {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 999px;
    font-size: 12px;
    font-weight: 500;
    line-height: 1.6;
    background: var(--color-bg);
    color: var(--color-muted);
    border: 1px solid var(--color-border);
}
.badge-primary { background: #dbeafe; color: var(--color-primary); border-color: var(--color-primary); }
.badge-success { background: var(--color-success-bg); color: var(--color-success); border-color: var(--color-success); }
.badge-danger  { background: var(--color-danger-bg);  color: var(--color-danger);  border-color: var(--color-danger); }
.badge-warning { background: var(--color-warning-bg); color: var(--color-warning); border-color: var(--color-warning); }
.badge-muted   { background: var(--color-bg);         color: var(--color-muted);   border-color: var(--color-border); }

/* ----- Breadcrumb ----- */
.breadcrumb {
    list-style: none;
    margin: 0 0 16px;
    padding: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 4px 6px;
    font-size: 14px;
    color: var(--color-muted);
}
.breadcrumb li { display: inline-flex; align-items: center; gap: 6px; }
.breadcrumb li + li::before { content: "›"; color: var(--color-muted); margin-right: 2px; }
.breadcrumb a { color: var(--color-muted); }
.breadcrumb a:hover { color: var(--color-primary); }
.breadcrumb .current { color: var(--color-text); font-weight: 600; }

/* ----- Tag chip ----- */
.tag-list { display: flex; flex-wrap: wrap; gap: 6px; }
.tag-chip {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 3px 10px;
    background: #eff6ff;
    color: var(--color-primary);
    border: 1px solid #bfdbfe;
    border-radius: 999px;
    font-size: 13px;
    text-decoration: none;
}
.tag-chip:hover { background: var(--color-primary); color: #fff; text-decoration: none; }
.tag-chip-remove {
    background: transparent;
    border: none;
    color: inherit;
    font-size: 16px;
    line-height: 1;
    padding: 0 0 0 4px;
    cursor: pointer;
}

/* Tag input (form) */
.tag-input-wrapper {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    padding: 6px;
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    min-height: 42px;
    align-items: center;
}
.tag-input-wrapper:focus-within {
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(37,99,235,.15);
}
.tag-input-wrapper input {
    flex: 1;
    min-width: 120px;
    border: none;
    outline: none;
    padding: 6px;
    font: inherit;
}

/* ----- Prompt detail ----- */
.prompt-header { margin-bottom: 16px; }
.prompt-header h1 { margin: 0 0 8px; font-size: 26px; }
.prompt-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px 16px;
    align-items: center;
    color: var(--color-muted);
    font-size: 14px;
}
.prompt-meta a { color: var(--color-text); }
.prompt-section { margin-top: 24px; }
.prompt-section h2 { font-size: 18px; margin: 0 0 8px; }
.prompt-content {
    background: #f8fafc;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    padding: 16px;
    white-space: pre-wrap;
    word-break: break-word;
    font-family: ui-monospace, "SFMono-Regular", Consolas, monospace;
    font-size: 14px;
    line-height: 1.55;
    overflow-x: auto;
}
.prompt-text { white-space: pre-wrap; word-break: break-word; }
.prompt-counters {
    display: flex;
    gap: 16px;
    color: var(--color-muted);
    font-size: 14px;
    margin-top: 12px;
}
.prompt-counters strong { color: var(--color-text); }

.prompt-banner {
    padding: 12px 16px;
    margin-bottom: 16px;
    border-radius: var(--radius-sm);
    border: 1px solid;
    font-size: 14px;
}
.prompt-banner-pending  { background: var(--color-warning-bg); color: var(--color-warning); border-color: var(--color-warning); }
.prompt-banner-rejected { background: var(--color-danger-bg);  color: var(--color-danger);  border-color: var(--color-danger); }
.prompt-banner-archived { background: var(--color-bg);         color: var(--color-muted);   border-color: var(--color-border); }

/* ----- My prompts (list) ----- */
.tabs {
    display: flex;
    gap: 4px;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: 16px;
    overflow-x: auto;
}
.tab {
    padding: 10px 16px;
    border: none;
    background: none;
    color: var(--color-muted);
    text-decoration: none;
    border-bottom: 2px solid transparent;
    font: inherit;
    cursor: pointer;
    white-space: nowrap;
}
.tab:hover { color: var(--color-text); text-decoration: none; }
.tab.is-active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
    font-weight: 500;
}
.tab-count {
    margin-left: 4px;
    font-size: 12px;
    color: var(--color-muted);
}
.tab.is-active .tab-count { color: var(--color-primary); }

.prompt-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 16px;
    margin-bottom: 12px;
}
.prompt-card h3 { margin: 0 0 4px; font-size: 17px; }
.prompt-card h3 a { color: var(--color-text); }
.prompt-card-meta {
    display: flex;
    gap: 8px 12px;
    flex-wrap: wrap;
    color: var(--color-muted);
    font-size: 13px;
    margin-top: 8px;
    align-items: center;
}
.prompt-card-actions {
    display: flex;
    gap: 6px;
    margin-top: 12px;
    flex-wrap: wrap;
}
.prompt-card-actions .btn { padding: 6px 12px; font-size: 13px; }
.rejection-note {
    background: var(--color-danger-bg);
    color: var(--color-danger);
    padding: 10px 12px;
    border-radius: var(--radius-sm);
    font-size: 13px;
    margin-top: 10px;
}

.empty-state {
    text-align: center;
    padding: 48px 16px;
    color: var(--color-muted);
}
.empty-state h3 { color: var(--color-text); margin: 0 0 8px; }

.pagination {
    display: flex;
    justify-content: center;
    gap: 4px;
    margin-top: 24px;
    list-style: none;
    padding: 0;
}
.pagination a, .pagination span {
    padding: 6px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    color: var(--color-text);
    text-decoration: none;
    font-size: 14px;
}
.pagination a:hover { background: var(--color-bg); text-decoration: none; }
.pagination .current { background: var(--color-primary); color: #fff; border-color: var(--color-primary); }
.pagination .disabled { color: var(--color-muted); pointer-events: none; }

/* ----- Two-col layout ----- */
.row { display: grid; grid-template-columns: 1fr; gap: 16px; }
@media (min-width: 720px) {
    .row.two-col { grid-template-columns: 1fr 1fr; }
}

/* ----- Search highlight ----- */
mark {
    background: #fef3c7;
    color: var(--color-warning);
    padding: 0 2px;
    border-radius: 2px;
    font-weight: 500;
}

/* ----- Discovery layout: sidebar filter + main content ----- */
.discovery-layout {
    display: grid;
    grid-template-columns: 240px 1fr;
    gap: 24px;
    align-items: start;
}
@media (max-width: 768px) {
    .discovery-layout { grid-template-columns: 1fr; }
}

.filter-sidebar {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 16px;
    position: sticky;
    top: 16px;
    max-height: calc(100vh - 32px);
    overflow-y: auto;
}
.filter-group { margin-bottom: 16px; padding-bottom: 16px; border-bottom: 1px solid var(--color-border); }
.filter-group:last-child { border-bottom: none; padding-bottom: 0; margin-bottom: 0; }
.filter-group h3 {
    font-size: 13px;
    text-transform: uppercase;
    letter-spacing: .5px;
    color: var(--color-muted);
    margin: 0 0 8px;
}
.filter-option {
    display: flex;
    gap: 6px;
    align-items: center;
    padding: 4px 0;
    font-size: 14px;
}
.filter-option input { cursor: pointer; }
.filter-option label { cursor: pointer; flex: 1; font-weight: normal; margin: 0; }
.filter-option .count { color: var(--color-muted); font-size: 12px; }

.active-chips {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 12px;
}
.active-chip {
    background: #eff6ff;
    color: var(--color-primary);
    border: 1px solid #bfdbfe;
    padding: 4px 8px;
    border-radius: 999px;
    font-size: 13px;
    text-decoration: none;
    display: inline-flex;
    gap: 4px;
    align-items: center;
}
.active-chip:hover { background: var(--color-primary); color: #fff; text-decoration: none; }

.results-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
    flex-wrap: wrap;
    gap: 8px;
}
.results-summary strong { font-size: 16px; }

/* ----- Hero search ----- */
.search-hero {
    background: linear-gradient(135deg, var(--color-primary) 0%, #1e40af 100%);
    color: #fff;
    padding: 48px 24px;
    border-radius: var(--radius);
    text-align: center;
    margin-bottom: 32px;
}
.search-hero h1 { color: #fff; font-size: 32px; margin: 0 0 8px; }
.search-hero p  { color: rgba(255,255,255,.85); margin: 0 0 24px; }
.search-hero .search-form {
    max-width: 520px;
    margin: 0 auto;
    display: flex;
    gap: 8px;
}
.search-hero .form-control { font-size: 16px; }

/* Header search bar (compact) */
.header-search {
    flex: 1;
    max-width: 320px;
}
.header-search input {
    width: 100%;
    padding: 6px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font: inherit;
    background: var(--color-bg);
}
.header-search input:focus {
    background: #fff;
    outline: none;
    border-color: var(--color-primary);
}

/* ----- Section headings ----- */
.section { margin-bottom: 40px; }
.section-header {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 16px;
}
.section-header h2 { margin: 0; font-size: 20px; }
.section-header a  { font-size: 14px; }

/* ----- Category cards (homepage) ----- */
.cat-card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
}
.cat-card {
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 20px;
    text-decoration: none;
    color: var(--color-text);
    display: block;
    text-align: center;
    transition: transform .12s, box-shadow .12s;
}
.cat-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
    text-decoration: none;
    border-color: var(--color-primary);
}
.cat-card-icon { font-size: 32px; margin-bottom: 8px; }
.cat-card-name { font-weight: 600; margin: 0 0 4px; }
.cat-card-count { color: var(--color-muted); font-size: 13px; }

/* Cards grid for prompt-card */
.prompt-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 12px;
}
.prompt-grid .prompt-card { margin: 0; }

/* Single column variant (search/list) */
.prompt-list .prompt-card { margin-bottom: 12px; }

/* ----- Engagement bar (Sprint 4 - like/save/copy/report) ----- */
.engagement-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    padding: 16px 0;
    border-top: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    margin: 16px 0;
}
.engagement-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 8px 14px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font: inherit;
    font-size: 14px;
    color: var(--color-text);
    cursor: pointer;
    transition: all .15s;
    min-height: 38px;
}
.engagement-btn:hover {
    background: var(--color-bg);
    border-color: var(--color-primary);
    color: var(--color-primary);
}
.engagement-btn:disabled { opacity: .6; cursor: wait; }
.engagement-btn.is-active {
    background: #fee2e2;
    border-color: var(--color-danger);
    color: var(--color-danger);
}
.engagement-btn .count {
    background: var(--color-bg);
    color: var(--color-muted);
    padding: 1px 8px;
    border-radius: 999px;
    font-size: 12px;
    font-weight: 600;
}
.engagement-btn.is-active .count {
    background: var(--color-danger);
    color: #fff;
}

/* ----- Comment thread (Sprint 4) ----- */
.comment-thread { display: flex; flex-direction: column; gap: 16px; }
.comment {
    display: flex;
    gap: 12px;
}
.comment-avatar {
    width: 40px; height: 40px;
    border-radius: 50%;
    flex-shrink: 0;
    object-fit: cover;
    background: var(--color-bg);
}
.comment-body {
    flex: 1;
    min-width: 0;
}
.comment-header {
    display: flex;
    gap: 8px;
    align-items: baseline;
    flex-wrap: wrap;
    font-size: 13px;
    margin-bottom: 4px;
}
.comment-author { font-weight: 600; color: var(--color-text); }
.comment-time   { color: var(--color-muted); }
.comment-content {
    background: var(--color-bg);
    padding: 10px 14px;
    border-radius: 10px;
    word-break: break-word;
    white-space: pre-wrap;
    font-size: 14px;
    line-height: 1.5;
}
.comment-actions {
    display: flex;
    gap: 12px;
    margin-top: 6px;
    font-size: 13px;
}
.comment-actions .btn-link { padding: 0; font-size: 13px; }
.comment-replies {
    margin-top: 12px;
    padding-left: 20px;
    border-left: 2px solid var(--color-border);
    display: flex;
    flex-direction: column;
    gap: 12px;
}
@media (max-width: 480px) {
    .comment-replies { padding-left: 12px; }
}

.reply-form { background: var(--color-bg); padding: 8px; border-radius: 8px; }

/* ----- Notification bell ----- */
.bell-wrapper {
    position: relative;
}
.bell-toggle {
    background: none;
    border: 1px solid transparent;
    width: 36px; height: 36px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    position: relative;
    font-size: 18px;
    line-height: 1;
}
.bell-toggle:hover { background: var(--color-bg); }
.bell-badge {
    position: absolute;
    top: 2px; right: 2px;
    background: var(--color-danger);
    color: #fff;
    font-size: 10px;
    font-weight: 700;
    padding: 1px 5px;
    border-radius: 999px;
    min-width: 16px;
    text-align: center;
    line-height: 1.4;
}
.bell-dropdown {
    position: absolute;
    top: 100%;
    right: 0;
    z-index: 60;
    width: 360px;
    max-width: calc(100vw - 24px);
    background: #fff;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    margin-top: 4px;
    display: none;
    max-height: 480px;
    overflow: hidden;
    flex-direction: column;
}
.bell-wrapper.is-open .bell-dropdown { display: flex; }
.bell-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    border-bottom: 1px solid var(--color-border);
}
.bell-body {
    flex: 1;
    overflow-y: auto;
}
.bell-footer {
    padding: 10px 16px;
    border-top: 1px solid var(--color-border);
    text-align: center;
    font-size: 14px;
}
.bell-item {
    margin: 0;
    border-bottom: 1px solid var(--color-border);
}
.bell-item:last-child { border-bottom: none; }
.bell-item.unread { background: #eff6ff; }
.bell-item-btn {
    width: 100%;
    display: flex;
    gap: 10px;
    align-items: flex-start;
    padding: 10px 14px;
    background: none;
    border: none;
    cursor: pointer;
    text-align: left;
    font: inherit;
    color: inherit;
}
.bell-item-btn:hover { background: var(--color-bg); }
.bell-item-icon { font-size: 18px; flex-shrink: 0; }
.bell-item-text {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 2px;
}
.bell-item-title { font-size: 13px; line-height: 1.4; word-break: break-word; }
.bell-item-time  { font-size: 11px; color: var(--color-muted); }
.bell-item-dot {
    width: 8px; height: 8px;
    background: var(--color-primary);
    border-radius: 50%;
    flex-shrink: 0;
    margin-top: 6px;
}

/* Notifications page rows */
.notif-row {
    border-bottom: 1px solid var(--color-border);
    padding: 12px 0;
}
.notif-row:last-child { border-bottom: none; }
.notif-row.is-unread { background: rgba(219, 234, 254, .3); margin: 0 -16px; padding: 12px 16px; }

/* ----- Nav: dropdown Categories ----- */
.nav-cat-wrapper { position: relative; }
.nav-cat-toggle {
    background: none;
    border: none;
    color: var(--color-muted);
    padding: 6px 10px;
    font: inherit;
    border-radius: var(--radius-sm);
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 4px;
}
.nav-cat-toggle:hover,
.nav-cat-wrapper:hover .nav-cat-toggle { background: var(--color-bg); color: var(--color-text); }

.nav-cat-dropdown {
    position: absolute;
    top: 100%;
    left: 0;
    z-index: 50;
    display: none;
    min-width: 240px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 6px 0;
    margin-top: 4px;
}
/* Bridge transparent giữ vùng hover khi chuột di từ button "Danh mục" xuống dropdown
   (lấp khoảng margin-top: 4px). */
.nav-cat-dropdown::before {
    content: "";
    position: absolute;
    top: -8px;       /* >= margin-top + buffer 1-2px */
    left: 0;
    right: 0;
    height: 8px;
}
.nav-cat-wrapper:hover .nav-cat-dropdown,
.nav-cat-wrapper.is-open .nav-cat-dropdown { display: block; }

.cat-menu { list-style: none; margin: 0; padding: 0; }
.cat-menu-root { /* root level shown in dropdown */ }
.cat-submenu {
    position: absolute;
    top: -7px;
    left: 100%;
    min-width: 220px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    padding: 6px 0;
    display: none;
}
/* Bridge transparent bên trái submenu - giữ hover khi chuột di chéo qua khoảng
   giữa parent link và submenu (đặc biệt khi chuột đi đường chéo lên/xuống). */
.cat-submenu::before {
    content: "";
    position: absolute;
    top: 0;
    left: -8px;      /* mở rộng vùng hover sang trái 8px */
    width: 8px;
    height: 100%;
}
.cat-item { position: relative; }
.cat-item:hover > .cat-submenu,
.cat-item.is-open > .cat-submenu { display: block; }

.cat-link {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    padding: 8px 16px;
    color: var(--color-text);
    text-decoration: none;
    white-space: nowrap;
}
.cat-link:hover { background: var(--color-bg); text-decoration: none; }
.cat-arrow { color: var(--color-muted); font-size: 14px; }

/* ----- Mobile hamburger ----- */
.nav-mobile-toggle {
    display: none;
    background: none;
    border: none;
    width: 36px;
    height: 36px;
    padding: 8px;
    cursor: pointer;
    flex-direction: column;
    justify-content: space-between;
}
.nav-mobile-toggle span {
    display: block;
    height: 2px;
    background: var(--color-text);
    border-radius: 1px;
}

/* ----- Responsive ----- */
@media (max-width: 768px) {
    .nav-mobile-toggle { display: flex; }
    .main-nav {
        order: 99;
        width: 100%;
        flex-direction: column;
        gap: 4px;
        align-items: stretch;
        display: none;
        padding-top: 8px;
    }
    .main-nav.is-open { display: flex; }
    .nav-cat-wrapper { width: 100%; }
    .nav-cat-toggle { width: 100%; justify-content: space-between; padding: 10px; }
    .nav-cat-wrapper:hover .nav-cat-dropdown { display: none; }
    .nav-cat-wrapper.is-open .nav-cat-dropdown { display: block; }
    .nav-cat-dropdown {
        position: static;
        box-shadow: none;
        border: none;
        margin: 0;
        padding-left: 12px;
    }
    .cat-submenu {
        position: static;
        box-shadow: none;
        border: none;
        padding-left: 12px;
        margin-top: 0;
    }
    .cat-item:hover > .cat-submenu { display: none; }
    .cat-item.is-open > .cat-submenu { display: block; }
}

@media (max-width: 480px) {
    .header-inner { flex-wrap: wrap; }
    .card { padding: 20px; }
    .hero h1 { font-size: 26px; }
    .error-code { font-size: 72px; }
}