/* ═══════════════════════════════════════════════════════════════
   learning-resources.css — Material 3-inspired redesign
   Page-specific styles for learning-resources hub & category pages
   ═══════════════════════════════════════════════════════════════ */

/* ─── Base ─────────────────────────────────────────────────── */

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
    background: var(--m3-surface, #FAFAF9);
    min-height: 100vh;
    padding: var(--space-5, 20px);
    padding-top: calc(var(--header-height, 60px) + var(--space-5, 20px));
    color: var(--m3-on-surface, #1C1B1F);
    -webkit-font-smoothing: antialiased;
}

html {
    scroll-behavior: smooth;
}

/* ─── Accessibility: Skip Link ──────────────────────────────── */

.skip-link {
    position: absolute;
    top: -40px;
    left: 0;
    background: var(--color-aws-orange, #dc7600);
    color: white;
    padding: 8px 16px;
    text-decoration: none;
    border-radius: 0 0 var(--radius-badge, 8px) 0;
    font-weight: 600;
    z-index: 1000;
}

.skip-link:focus {
    top: 0;
}

/* ─── Accessibility: Focus Indicators ───────────────────────── */

a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
[tabindex]:focus-visible {
    outline: 3px solid var(--color-aws-orange, #dc7600);
    outline-offset: 2px;
}

/* ─── Container ─────────────────────────────────────────────── */

.container {
    max-width: var(--container-max-width, 1200px);
    margin: 0 auto;
    background-color: var(--ds-bg-card, #FFFFFF);
    border-radius: var(--radius-container, 24px);
    box-shadow: var(--shadow-container, 0 1px 4px rgba(0,0,0,0.03));
    overflow: hidden;
}

/* ─── Hero / Header ─────────────────────────────────────────── */

.header {
    background: linear-gradient(160deg, #1a2332 0%, var(--color-aws-dark, #232F3E) 50%, #2d3a4a 100%);
    color: white;
    padding: var(--space-16, 64px) var(--space-10, 40px);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.header::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(ellipse 80% 50% at 70% 20%, rgba(220, 118, 0, 0.06) 0%, transparent 70%);
    pointer-events: none;
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--space-3, 12px);
    color: var(--color-aws-orange, #dc7600);
    letter-spacing: -0.025em;
}

.header p {
    font-size: 1.1rem;
    color: rgba(255,255,255,0.65);
    line-height: 1.6;
}

.header-back-link {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2, 8px);
    color: rgba(255,255,255,0.8);
    padding: var(--space-2, 8px) var(--space-4, 16px);
    background: rgba(255,255,255,0.1);
    border-radius: var(--radius-badge, 8px);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s ease;
    margin-bottom: var(--space-6, 24px);
}

.header-back-link:hover {
    background: rgba(255,255,255,0.2);
    color: white;
}

/* Hero stats row */
.hero-stats {
    display: flex;
    justify-content: center;
    gap: var(--space-3, 12px);
    margin-top: var(--space-6, 24px);
    flex-wrap: wrap;
}

.hero-stat {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2, 8px);
    padding: var(--space-2, 8px) var(--space-5, 20px);
    background: rgba(255,255,255,0.06);
    border: none;
    border-radius: var(--radius-pill, 100px);
    font-size: 0.82rem;
    color: rgba(255,255,255,0.9);
    backdrop-filter: blur(8px);
    letter-spacing: 0.01em;
}

.hero-stat-value {
    font-weight: 700;
    color: var(--color-aws-orange, #dc7600);
}

/* Hero CTA buttons */
.hero-cta-group {
    display: flex;
    justify-content: center;
    gap: var(--space-3, 12px);
    margin-top: var(--space-6, 24px);
    flex-wrap: wrap;
}

.hero-cta {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2, 8px);
    padding: var(--space-3, 12px) var(--space-6, 24px);
    border-radius: var(--radius-pill, 100px);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.hero-cta-primary {
    background: var(--color-aws-orange, #dc7600);
    color: white;
    box-shadow: 0 2px 8px rgba(220, 118, 0, 0.3);
}

.hero-cta-primary:hover {
    background: var(--color-aws-orange-hover, #EC7211);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(220, 118, 0, 0.4);
}

.hero-cta-secondary {
    background: rgba(255,255,255,0.12);
    color: white;
    border: 1px solid rgba(255,255,255,0.12);
}

.hero-cta-secondary:hover {
    background: rgba(255,255,255,0.2);
}

/* ─── Content Area ──────────────────────────────────────────── */

.content {
    padding: var(--space-12, 48px) var(--space-10, 40px);
}

/* ─── Shared Section Card Style ─────────────────────────────── */

.learning-mode-section,
.domain-nav-section,
.search-section,
.filter-section {
    background: var(--m3-surface-container, #F5F4F2);
    border-radius: var(--radius-card, 16px);
    padding: var(--space-8, 32px);
    margin-bottom: var(--space-8, 32px);
}

/* ─── Section Headings (unified) ────────────────────────────── */

.learning-mode-section h3,
.domain-nav-section h3,
.search-section h3,
.filter-section h3 {
    color: var(--m3-on-surface-variant, #49454F);
    margin-bottom: var(--space-4, 16px);
    font-size: 0.82rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: var(--space-2, 8px);
    letter-spacing: 0.06em;
    text-transform: uppercase;
}

/* ─── Learning Mode Cards ───────────────────────────────────── */

.learning-mode-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: var(--space-4, 16px);
}

.learning-mode-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-1, 4px);
    padding: var(--space-5, 20px) var(--space-4, 16px);
    background: var(--ds-bg-card, white);
    border: 1px solid transparent;
    border-radius: var(--radius-card, 16px);
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
    text-align: center;
    font-family: inherit;
    font-size: inherit;
    box-shadow: var(--shadow-card);
}

.learning-mode-card:hover {
    border-color: var(--m3-outline, #CAC4D0);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card-hover);
}

.learning-mode-card[aria-pressed="true"] {
    background: linear-gradient(135deg, var(--color-aws-orange, #dc7600) 0%, var(--color-aws-orange-hover, #EC7211) 100%);
    color: white;
    border-color: var(--color-aws-orange, #dc7600);
    box-shadow: 0 4px 12px rgba(220, 118, 0, 0.25);
}

.learning-mode-card[aria-pressed="true"] .learning-mode-desc {
    color: rgba(255, 255, 255, 0.85);
}

.learning-mode-icon {
    font-size: 1.75em;
    line-height: 1;
}

.learning-mode-title {
    font-weight: 600;
    font-size: 0.9rem;
}

.learning-mode-desc {
    font-size: 0.78rem;
    color: var(--color-text-secondary, #6B7280);
    line-height: 1.4;
}

/* ─── Exam Domain Cards ─────────────────────────────────────── */

.domain-nav-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: var(--space-4, 16px);
}

.domain-card {
    display: flex;
    align-items: center;
    gap: var(--space-3, 12px);
    padding: var(--space-5, 20px) var(--space-6, 24px);
    background: var(--ds-bg-card, white);
    border: 1px solid transparent;
    border-radius: var(--radius-card, 16px);
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
    text-align: left;
    font-family: inherit;
    font-size: inherit;
    width: 100%;
    box-shadow: var(--shadow-card);
}

.domain-card:hover {
    border-color: var(--m3-outline, #CAC4D0);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card-hover);
}

.domain-card[aria-pressed="true"] {
    background: linear-gradient(135deg, var(--color-aws-orange, #dc7600) 0%, var(--color-aws-orange-hover, #EC7211) 100%);
    color: white;
    border-color: var(--color-aws-orange, #dc7600);
    box-shadow: 0 4px 12px rgba(220, 118, 0, 0.25);
}

.domain-card[aria-pressed="true"] .domain-title,
.domain-card[aria-pressed="true"] .domain-id {
    color: white;
}

.domain-card[aria-pressed="true"] .domain-weight,
.domain-card[aria-pressed="true"] .domain-count {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
}

.domain-icon {
    font-size: 1.75em;
    line-height: 1;
    flex-shrink: 0;
}

.domain-info {
    flex: 1;
    min-width: 0;
}

.domain-id {
    display: block;
    font-size: 0.7rem;
    font-weight: 700;
    color: var(--color-aws-orange, #dc7600);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.domain-title {
    display: block;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--m3-on-surface, #1C1B1F);
    line-height: 1.4;
}

.domain-stats {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-1, 4px);
    flex-shrink: 0;
}

.domain-weight {
    font-size: 0.78rem;
    font-weight: 700;
    background: rgba(220, 118, 0, 0.1);
    color: var(--color-aws-orange, #dc7600);
    padding: 2px 10px;
    border-radius: var(--radius-badge, 8px);
}

.domain-count {
    font-size: 0.72rem;
    color: var(--m3-on-surface-variant, #49454F);
    background: var(--m3-surface-container, #F5F4F2);
    padding: 2px 10px;
    border-radius: var(--radius-badge, 8px);
}

/* ─── Search Section ────────────────────────────────────────── */

.search-section {
    background: transparent;
    padding: var(--space-10, 40px) var(--space-8, 32px);
}

.search-container {
    position: relative;
    max-width: 720px;
    margin: 0 auto;
}

.search-input {
    width: 100%;
    padding: var(--space-5, 20px) 56px var(--space-5, 20px) var(--space-6, 24px);
    font-size: 1.05rem;
    border: 1px solid transparent;
    border-radius: var(--radius-card, 16px);
    background-color: var(--ds-bg-card, white);
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
    outline: none;
    box-shadow: var(--shadow-elevated);
}

.search-input:focus {
    border-color: transparent;
    box-shadow: var(--shadow-elevated), 0 0 0 3px rgba(220, 118, 0, 0.1);
}

.search-input::placeholder {
    color: var(--color-text-tertiary, #6f7682);
}

.search-clear {
    position: absolute;
    right: 14px;
    top: 50%;
    transform: translateY(-50%);
    background: none;
    border: none;
    font-size: 1.3em;
    color: var(--m3-on-surface-variant, #49454F);
    cursor: pointer;
    padding: 5px;
    display: none;
    transition: color 0.2s ease;
    border-radius: 50%;
}

.search-clear:hover {
    color: var(--color-aws-orange, #dc7600);
}

.search-clear.show {
    display: block;
}

/* Search results */
.search-results {
    margin-top: var(--space-5, 20px);
    display: none;
}

.search-results.show {
    display: block;
}

.search-results-header {
    color: var(--m3-on-surface, #1C1B1F);
    font-size: 0.95rem;
    margin-bottom: var(--space-4, 16px);
    text-align: center;
}

.search-results-count {
    color: var(--color-aws-orange, #dc7600);
    font-weight: 700;
}

.search-results-list {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--space-3, 12px);
    max-height: 500px;
    overflow-y: auto;
    padding: var(--space-4, 16px);
    background-color: var(--ds-bg-card, white);
    border-radius: var(--radius-input, 12px);

}

.search-result-item {
    background-color: var(--m3-surface-container-low, #FDFCFA);
    border: 1px solid transparent;
    border-radius: var(--radius-input, 12px);
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
}

.search-result-item:hover {
    background-color: var(--m3-surface-container-low, #FDFCFA);
    border-color: var(--m3-outline, #CAC4D0);
    transform: translateY(-1px);
    box-shadow: var(--shadow-card);
}

.search-result-item a {
    display: block;
    padding: var(--space-3, 12px) var(--space-4, 16px);
    color: var(--m3-on-surface, #1C1B1F);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.9rem;
}

.search-result-item a:hover {
    color: var(--color-aws-orange, #dc7600);
}

.search-result-category {
    display: inline-block;
    font-size: 0.72rem;
    color: var(--m3-on-surface-variant, #49454F);
    background-color: var(--m3-surface-container, #F5F4F2);
    padding: 2px 8px;
    border-radius: var(--radius-badge, 8px);
    margin-top: 4px;
}

.search-result-service {
    display: inline-block;
    font-size: 0.7rem;
    color: var(--color-aws-orange, #dc7600);
    background-color: rgba(220, 118, 0, 0.08);
    padding: 2px 8px;
    border-radius: var(--radius-badge, 8px);
    margin-top: 3px;
    margin-left: 4px;
}

.search-no-results {
    text-align: center;
    padding: var(--space-10, 40px) var(--space-5, 20px);
    color: var(--m3-on-surface-variant, #49454F);
    background-color: var(--ds-bg-card, white);
    border-radius: var(--radius-input, 12px);
}

.search-no-results-icon {
    font-size: 2.5em;
    margin-bottom: var(--space-4, 16px);
    opacity: 0.6;
}

.search-no-results p {
    font-size: 0.95rem;
}

/* ─── Filter Section ────────────────────────────────────────── */

.filter-section {
    background: var(--m3-surface-container-low, #FDFCFA);
}

.filter-controls {
    display: flex;
    gap: var(--space-4, 16px);
    align-items: flex-end;
    flex-wrap: wrap;
}

.filter-group {
    flex: 1;
    min-width: 180px;
}

.filter-group label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--m3-on-surface-variant, #49454F);
    margin-bottom: var(--space-1, 4px);
    letter-spacing: 0.02em;
    text-transform: uppercase;
}

.filter-group select {
    width: 100%;
    padding: var(--space-3, 12px) 36px var(--space-3, 12px) var(--space-3, 12px);
    font-size: 0.9rem;
    border: 1px solid var(--m3-outline-variant, #E7E0EC);
    border-radius: var(--radius-input, 12px);
    background-color: var(--ds-bg-card, white);
    color: var(--m3-on-surface, #1C1B1F);
    cursor: pointer;
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%236B7280' stroke-width='2' fill='none'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 12px center;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.filter-group select:focus {
    outline: none;
    border-color: var(--color-aws-orange, #dc7600);
    box-shadow: 0 0 0 3px rgba(220, 118, 0, 0.12);
}

.filter-clear-btn {
    padding: var(--space-3, 12px) var(--space-5, 20px);
    font-size: 0.875rem;
    background: var(--color-error, #EF4444);
    color: white;
    border: none;
    border-radius: var(--radius-input, 12px);
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s ease;
    white-space: nowrap;
}

.filter-clear-btn:hover {
    background: #DC2626;
    transform: translateY(-1px);
}

.filter-status {
    margin-top: var(--space-3, 12px);
    padding: var(--space-2, 8px) var(--space-4, 16px);
    background: var(--ds-bg-card, white);
    border-radius: var(--radius-badge, 8px);
    font-size: 0.9rem;
    color: var(--m3-on-surface, #1C1B1F);
}

.filter-status strong {
    color: var(--color-aws-orange, #dc7600);
}

/* Filter hidden states */
.major-category.filter-hidden,
.toc-section.filter-hidden,
.resource-list li.filter-hidden {
    display: none !important;
}

/* Filter 0 results */
.filter-no-results {
    text-align: center;
    padding: var(--space-8, 32px) var(--space-5, 20px);
    margin-top: var(--space-4, 16px);
    background: #FEF3C7;
    border: 1px solid #F59E0B;
    border-radius: var(--radius-input, 12px);
    color: #92400E;
}

.filter-no-results-icon {
    font-size: 2em;
    margin-bottom: var(--space-2, 8px);
}

.filter-no-results-hint {
    font-size: 0.85rem;
    margin-top: var(--space-2, 8px);
}

/* ─── Resource List (Card Grid) ─────────────────────────────── */

.resource-list {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-5, 20px);
    padding: 0;
}

.resource-list li {
    position: relative;
    display: flex;
    flex-direction: column;
    background-color: var(--ds-bg-card, white);
    border: 1px solid transparent;
    border-radius: var(--radius-card, 16px);
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
    padding-right: 40px;
    box-shadow: var(--shadow-card);
}

.resource-list li:hover {
    background-color: var(--m3-surface-container-low, #FDFCFA);
    border-color: var(--m3-outline, #CAC4D0);
    transform: translateY(-2px);
    box-shadow: var(--shadow-card-hover);
}

.resource-list a {
    display: block;
    padding: var(--space-5, 20px) var(--space-6, 24px) var(--space-3, 12px);
    color: var(--m3-on-surface, #1C1B1F);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.92rem;
    transition: color 0.2s ease;
    line-height: 1.5;
    word-break: break-word;
    overflow-wrap: anywhere;
}

.resource-list a:hover {
    color: var(--color-aws-orange, #dc7600);
}

.resource-count {
    display: inline-block;
    background-color: var(--color-aws-orange, #dc7600);
    color: white;
    padding: 3px 12px;
    border-radius: var(--radius-pill, 100px);
    font-size: 0.8rem;
    font-weight: 600;
    margin-left: var(--space-2, 8px);
}

/* Resource summary */
.resource-summary {
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    font-size: 0.8rem;
    color: var(--color-text-secondary, #6B7280);
    line-height: 1.5;
    margin-top: 0;
    padding: 0 var(--space-6, 24px) var(--space-3, 12px);
}

/* Resource metadata badges */
.resource-meta {
    display: flex;
    flex-wrap: wrap;
    gap: var(--space-2, 8px);
    padding: 0 var(--space-6, 24px) var(--space-4, 16px);
}

.meta-badge {
    display: inline-block;
    font-size: 0.7rem;
    padding: 3px 8px;
    border-radius: var(--radius-badge, 8px);
    font-weight: 500;
    line-height: 1.4;
}

.difficulty-beginner {
    background-color: var(--m3-surface-container-high, #EFEEEC);
    color: var(--m3-on-surface-variant, #49454F);
}

.difficulty-intermediate {
    background-color: var(--m3-surface-container-high, #EFEEEC);
    color: var(--m3-on-surface-variant, #49454F);
}

.difficulty-advanced {
    background-color: var(--m3-surface-container-high, #EFEEEC);
    color: var(--m3-on-surface-variant, #49454F);
}

.time-badge {
    background-color: var(--m3-surface-container-high, #EFEEEC);
    color: var(--m3-on-surface-variant, #49454F);
}

.domain-badge {
    background-color: var(--m3-surface-container-high, #EFEEEC);
    color: var(--m3-on-surface-variant, #49454F);
}

/* Bookmark icon */
.resource-list .bookmark-icon {
    position: absolute;
    top: var(--space-3, 12px);
    right: var(--space-2, 8px);
    margin-left: 0;
    z-index: 1;
}

/* ─── Major Category (Section Wrapper) ──────────────────────── */

.major-category {
    margin-bottom: var(--space-16, 64px);
    background: var(--ds-bg-card, white);
    border-radius: var(--radius-card-lg, 20px);
    padding: var(--space-10, 40px);
    box-shadow: var(--shadow-card);
    transition: box-shadow 0.25s cubic-bezier(0.2, 0, 0, 1);
}

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

.major-category-header {
    color: var(--m3-on-surface, #1C1B1F);
    font-size: 1.85rem;
    font-weight: 700;
    margin-bottom: var(--space-6, 24px);
    display: flex;
    align-items: center;
    gap: var(--space-3, 12px);
    padding-bottom: var(--space-6, 24px);
    border-bottom: 1px solid var(--m3-surface-container-high, #EFEEEC);
    letter-spacing: -0.02em;
}

.major-category-icon {
    font-size: 1.2em;
}

.section-icon {
    font-size: 1.1em;
}

/* Section within category */
.toc-section {
    margin-bottom: var(--space-10, 40px);
    border-left: 2px solid var(--m3-surface-container-high, #EFEEEC);
    padding-left: var(--space-6, 24px);
    margin-left: var(--space-2, 8px);
    padding-top: var(--space-3, 12px);
    padding-bottom: var(--space-3, 12px);
    border-radius: 0 var(--radius-badge, 8px) var(--radius-badge, 8px) 0;
}

.toc-section:last-child {
    margin-bottom: 0;
}

.toc-section h2 {
    color: var(--m3-on-surface, #1C1B1F);
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: var(--space-5, 20px);
    display: flex;
    align-items: center;
    gap: var(--space-3, 12px);
    letter-spacing: -0.01em;
}

/* ─── Knowledge Base Navigation ─────────────────────────────── */

.knowledge-base-nav {
    margin-bottom: var(--space-8, 32px);
}

.kb-button {
    display: flex;
    align-items: center;
    background: linear-gradient(135deg, #10B981 0%, #059669 100%);
    color: white;
    text-decoration: none;
    padding: var(--space-5, 20px) var(--space-6, 24px);
    border-radius: var(--radius-card, 16px);
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.2);
    transition: all 0.2s ease;
}

.kb-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.3);
}

.kb-icon {
    font-size: 2.5em;
    margin-right: var(--space-5, 20px);
}

.kb-content {
    flex: 1;
}

.kb-title {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: var(--space-1, 4px);
}

.kb-desc {
    font-size: 0.9rem;
    opacity: 0.9;
}

/* ─── Category Navigation (legacy) ──────────────────────────── */

.category-nav {
    background: var(--m3-surface-container, #F5F4F2);
    border-radius: var(--radius-card, 16px);
    padding: var(--space-6, 24px);
    margin-bottom: var(--space-8, 32px);
}

.category-nav h3 {
    color: var(--m3-on-surface, #1C1B1F);
    margin-bottom: var(--space-5, 20px);
    font-size: 1.1rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: var(--space-2, 8px);
}

.category-links {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--space-3, 12px);
}

.category-link {
    display: flex;
    align-items: center;
    gap: var(--space-2, 8px);
    padding: var(--space-3, 12px) var(--space-4, 16px);
    background-color: var(--ds-bg-card, white);
    border: 1px solid transparent;
    border-radius: var(--radius-input, 12px);
    text-decoration: none;
    color: var(--m3-on-surface, #1C1B1F);
    font-weight: 500;
    font-size: 0.9rem;
    transition: all 0.25s cubic-bezier(0.2, 0, 0, 1);
    cursor: pointer;
}

.category-link:hover,
.category-link:focus {
    background: var(--color-aws-orange, #dc7600);
    color: white;
    border-color: var(--color-aws-orange, #dc7600);
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(220, 118, 0, 0.2);
}

.category-link:focus-visible {
    outline: 3px solid var(--color-aws-dark, #232F3E);
    outline-offset: 4px;
}

.category-link-icon {
    font-size: 1.3em;
}

.category-link-text {
    flex: 1;
}

.category-link-count {
    background-color: var(--m3-surface-container, #F5F4F2);
    color: var(--m3-on-surface-variant, #49454F);
    padding: 3px 10px;
    border-radius: var(--radius-badge, 8px);
    font-size: 0.8rem;
    font-weight: 600;
}

.category-link:hover .category-link-count {
    background-color: rgba(255, 255, 255, 0.25);
    color: white;
}

/* ─── Footer Note ───────────────────────────────────────────── */

.footer-note {
    text-align: center;
    margin-top: var(--space-12, 48px);
    padding: var(--space-6, 24px);
    background-color: var(--m3-surface-container, #F5F4F2);
    border-radius: var(--radius-card, 16px);
}

.footer-note p {
    color: var(--m3-on-surface-variant, #49454F);
    font-size: 0.9rem;
    line-height: 1.7;
}

/* ─── Fixed Navigation Header ───────────────────────────────── */

.fixed-nav-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height, 60px);
    background: var(--nav-bg-solid, #0F172A);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
    z-index: var(--z-header, 1002);
    display: flex;
    align-items: center;
    backdrop-filter: blur(8px);
}

.fixed-nav-container {
    width: 100%;
    max-width: var(--container-max-width, 1200px);
    margin: 0 auto;
    padding: 0 var(--space-6, 24px);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.fixed-nav-logo {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--color-aws-orange, #dc7600);
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: var(--space-2, 8px);
    transition: opacity 0.2s ease;
}

.fixed-nav-logo:hover {
    opacity: 0.9;
}

.fixed-nav-links {
    display: flex;
    gap: var(--space-5, 20px);
    align-items: center;
}

.fixed-nav-links a {
    color: var(--nav-link-color, #CBD5E1);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.875rem;
    padding: var(--space-2, 8px) var(--space-4, 16px);
    border-radius: var(--radius-badge, 8px);
    transition: all 0.2s ease;
    white-space: nowrap;
}

.fixed-nav-links a:hover,
.fixed-nav-links a:focus {
    background-color: var(--nav-link-active-bg, rgba(255, 255, 255, 0.1));
    color: var(--nav-link-hover, #FFFFFF);
}

/* ─── Reading Progress Bar ──────────────────────────────────── */

.reading-progress {
    position: fixed;
    top: var(--header-height, 60px);
    left: 0;
    width: 100%;
    height: 3px;
    background-color: transparent;
    z-index: var(--z-progress-bar, 1001);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.reading-progress.show {
    opacity: 1;
}

.reading-progress-bar {
    height: 100%;
    background: var(--color-aws-orange, #dc7600);
    width: 0%;
    transition: width 0.1s ease;
    border-radius: 0 2px 2px 0;
}

/* ─── Scroll-to-top Button ──────────────────────────────────── */

.scroll-to-top {
    position: fixed;
    bottom: var(--space-8, 32px);
    right: var(--space-8, 32px);
    width: 48px;
    height: 48px;
    background: var(--color-aws-orange, #dc7600);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.3em;
    cursor: pointer;
    box-shadow: 0 4px 12px rgba(220, 118, 0, 0.3);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s cubic-bezier(0.2, 0, 0, 1);
    z-index: var(--z-scroll-top, 1000);
    display: flex;
    align-items: center;
    justify-content: center;
}

.scroll-to-top.show {
    opacity: 1;
    visibility: visible;
}

.scroll-to-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(220, 118, 0, 0.4);
}

.scroll-to-top:active {
    transform: translateY(-1px);
}

/* ─── Focus-visible Enhancements ────────────────────────────── */

.learning-mode-card:focus-visible,
.domain-card:focus-visible {
    outline: 3px solid var(--color-aws-orange, #dc7600);
    outline-offset: 2px;
}

/* ═══════════════════════════════════════════════════════════════
   DARK MODE
   ═══════════════════════════════════════════════════════════════ */

[data-theme="dark"] body {
    background: var(--m3-surface, #1C1B1F);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .container {
    background-color: var(--ds-bg-card, #1E293B);
    border: 1px solid var(--ds-border, #334155);
}

/* Dark: sections */
[data-theme="dark"] .learning-mode-section,
[data-theme="dark"] .domain-nav-section,
[data-theme="dark"] .filter-section {
    background: var(--m3-surface-container-low, #17161A);
}

[data-theme="dark"] .search-section {
    background: transparent;
}

/* Dark: section headings */
[data-theme="dark"] .learning-mode-section h3,
[data-theme="dark"] .domain-nav-section h3,
[data-theme="dark"] .search-section h3,
[data-theme="dark"] .filter-section h3 {
    color: var(--m3-on-surface, #E6E1E5);
}

/* Dark: learning mode cards */
[data-theme="dark"] .learning-mode-card {
    background: var(--m3-surface-container, #211F26);
    border-color: var(--m3-outline-variant, #49454F);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .learning-mode-card:hover {
    border-color: var(--color-aws-orange, #dc7600);
}

[data-theme="dark"] .learning-mode-desc {
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* Dark: domain cards */
[data-theme="dark"] .domain-card {
    background: var(--m3-surface-container, #211F26);
    border-color: var(--m3-outline-variant, #49454F);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .domain-card:hover {
    border-color: var(--color-aws-orange, #dc7600);
}

[data-theme="dark"] .domain-id {
    color: var(--color-aws-orange, #dc7600);
}

[data-theme="dark"] .domain-title {
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .domain-weight {
    background: rgba(220, 118, 0, 0.15);
    color: var(--color-aws-orange, #dc7600);
}

[data-theme="dark"] .domain-count {
    background: var(--m3-surface-container-high, #2B2930);
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* Dark: search */
[data-theme="dark"] .search-input {
    background-color: var(--m3-surface-container, #211F26);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .search-results-list {
    background-color: var(--m3-surface-container, #211F26);
}

[data-theme="dark"] .search-result-item {
    background-color: var(--m3-surface-container-low, #17161A);
    border-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .search-result-item:hover {
    background-color: rgba(220, 118, 0, 0.08);
    border-color: var(--color-aws-orange, #dc7600);
}

[data-theme="dark"] .search-no-results {
    background-color: var(--m3-surface-container, #211F26);
}

/* Dark: filters */
[data-theme="dark"] .filter-group select {
    background-color: var(--m3-surface-container, #211F26);
    color: var(--m3-on-surface, #E6E1E5);
    border-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .filter-status {
    background: var(--m3-surface-container, #211F26);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .filter-no-results {
    background: #78350F;
    border-color: #D97706;
    color: #FDE68A;
}

/* Dark: resource cards */
[data-theme="dark"] .resource-list li {
    background-color: var(--m3-surface-container, #211F26);
    border-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .resource-list li:hover {
    background-color: rgba(220, 118, 0, 0.06);
    border-color: var(--m3-outline, #938F99);
}

[data-theme="dark"] .resource-list a {
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .resource-summary {
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* Dark: badges */
[data-theme="dark"] .difficulty-beginner,
[data-theme="dark"] .difficulty-intermediate,
[data-theme="dark"] .difficulty-advanced {
    background-color: var(--m3-surface-container-high, #2B2930);
    color: var(--m3-on-surface-variant, #CAC4D0);
}

[data-theme="dark"] .time-badge {
    background-color: var(--m3-surface-container-high, #2B2930);
    color: var(--m3-on-surface-variant, #CAC4D0);
}

[data-theme="dark"] .domain-badge {
    background-color: var(--m3-surface-container-high, #2B2930);
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* Dark: major category */
[data-theme="dark"] .major-category {
    background: var(--m3-surface-container, #211F26);
}

[data-theme="dark"] .major-category-header {
    color: var(--m3-on-surface, #E6E1E5);
    border-bottom-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .toc-section {
    border-left-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .toc-section h2 {
    color: var(--m3-on-surface, #E6E1E5);
}

/* Dark: footer note */
[data-theme="dark"] .footer-note {
    background-color: var(--m3-surface-container, #211F26);
}

[data-theme="dark"] .footer-note p {
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* Dark: nav */
[data-theme="dark"] .fixed-nav-header {
    background: var(--nav-bg-solid, #020617);
    border-bottom: 1px solid var(--nav-border, rgba(255, 255, 255, 0.06));
}

/* Dark: reading progress */
[data-theme="dark"] .reading-progress {
    background-color: var(--m3-outline-variant, #49454F);
}

[data-theme="dark"] .scroll-to-top {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.4);
}

/* Dark: category nav */
[data-theme="dark"] .category-nav {
    background: var(--m3-surface-container-low, #17161A);
}

[data-theme="dark"] .category-link {
    background-color: var(--m3-surface-container, #211F26);
    border-color: var(--m3-outline-variant, #49454F);
    color: var(--m3-on-surface, #E6E1E5);
}

[data-theme="dark"] .category-link-count {
    background-color: var(--m3-surface-container-high, #2B2930);
    color: var(--m3-on-surface-variant, #CAC4D0);
}

/* ═══════════════════════════════════════════════════════════════
   RESPONSIVE
   ═══════════════════════════════════════════════════════════════ */

/* Tablet (769px–1024px) */
@media (min-width: 769px) and (max-width: 1024px) {
    .resource-list {
        grid-template-columns: repeat(2, 1fr);
    }

    .learning-mode-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

/* Mobile (≤768px) */
@media (max-width: 768px) {
    body {
        padding: var(--space-3, 12px);
        padding-top: calc(var(--header-height, 60px) + var(--space-3, 12px));
    }

    .header {
        padding: var(--space-8, 32px) var(--space-5, 20px);
    }

    .header h1 {
        font-size: 1.75rem;
    }

    .header p {
        font-size: 0.95rem;
    }

    .content {
        padding: var(--space-5, 20px);
    }

    .resource-list {
        grid-template-columns: 1fr;
    }

    .resource-list li {
        padding-right: 36px;
    }

    .resource-list .bookmark-icon {
        top: 10px;
        right: 4px;
    }

    .toc-section h2 {
        font-size: 1.2rem;
    }

    .kb-button {
        flex-direction: column;
        text-align: center;
        padding: var(--space-5, 20px);
    }

    .kb-icon {
        font-size: 2em;
        margin-right: 0;
        margin-bottom: var(--space-2, 8px);
    }

    .kb-title {
        font-size: 1.15rem;
    }

    .category-links {
        grid-template-columns: 1fr;
    }

    .category-link {
        padding: var(--space-3, 12px) var(--space-4, 16px);
        min-height: 44px;
    }

    .scroll-to-top {
        bottom: var(--space-5, 20px);
        right: var(--space-5, 20px);
        width: 44px;
        height: 44px;
        font-size: 1.2em;
    }

    .major-category {
        padding: var(--space-6, 24px);
        margin-bottom: var(--space-10, 40px);
        border-radius: var(--radius-card, 16px);
    }

    .major-category-header {
        font-size: 1.5rem;
    }

    .fixed-nav-container {
        padding: 0 var(--space-4, 16px);
    }

    .fixed-nav-logo {
        font-size: 1.05rem;
    }

    .fixed-nav-links {
        gap: var(--space-2, 8px);
    }

    .fixed-nav-links a {
        font-size: 0.8rem;
        padding: var(--space-1, 4px) var(--space-3, 12px);
    }

    .learning-mode-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .learning-mode-section,
    .domain-nav-section,
    .search-section,
    .filter-section {
        padding: var(--space-5, 20px);
    }

    .domain-nav-grid {
        grid-template-columns: 1fr;
    }

    .domain-card {
        padding: var(--space-3, 12px) var(--space-4, 16px);
    }

    .resource-meta {
        padding: 0 var(--space-4, 16px) var(--space-2, 8px);
    }

    .filter-controls {
        flex-direction: column;
        gap: var(--space-3, 12px);
    }

    .filter-group {
        min-width: 100%;
    }

    .hero-stats {
        flex-direction: column;
        align-items: center;
        gap: var(--space-2, 8px);
    }

    .hero-cta-group {
        flex-direction: column;
        align-items: center;
    }

    .hero-cta {
        width: 100%;
        justify-content: center;
        max-width: 280px;
    }
}

/* Extra small (≤480px) */
@media (max-width: 480px) {
    body {
        padding: var(--space-2, 8px);
        padding-top: calc(var(--header-height, 60px) + var(--space-2, 8px));
    }

    .header {
        padding: var(--space-6, 24px) var(--space-4, 16px);
    }

    .header h1 {
        font-size: 1.5rem;
    }

    .content {
        padding: var(--space-4, 16px);
    }

    .learning-mode-section,
    .domain-nav-section,
    .search-section,
    .filter-section {
        padding: var(--space-4, 16px);
    }

    .container {
        border-radius: var(--radius-card, 16px);
    }
}

/* Print */
@media print {
    body {
        background: white;
        padding: 0;
    }

    .fixed-nav-header,
    .reading-progress,
    .scroll-to-top,
    .skip-link {
        display: none;
    }

    .container {
        box-shadow: none;
        border-radius: 0;
    }
}