/* ══════════════════════════════════════════════
   CSS VARIABLES — Matching your site palette
   ══════════════════════════════════════════════ */
:root {
    --obsidian: #080B12;
    --card-bg: #0F1320;
    --card-bg-alt: #111627;
    --card-border: #1C2233;
    --card-hover: #141929;
    --surface-raised: #161B2E;
    --surface-sunken: #0A0E18;

    --mint: #00E8A0;
    --mint-dim: rgba(0, 232, 160, 0.10);
    --mint-medium: rgba(0, 232, 160, 0.18);
    --mint-hover: #00C887;

    --purple: #B882FF;
    --purple-dim: rgba(184, 130, 255, 0.10);
    --purple-medium: rgba(184, 130, 255, 0.18);
    --purple-hover: #A060FF;

    --amber: #F59E0B;
    --amber-dim: rgba(245, 158, 11, 0.10);
    --amber-medium: rgba(245, 158, 11, 0.18);

    --coral: #FF6B6B;
    --coral-dim: rgba(255, 107, 107, 0.10);

    --pink: #F472B6;
    --pink-dim: rgba(244, 114, 182, 0.10);
    --pink-medium: rgba(244, 114, 182, 0.18);

    --blue: #60A5FA;
    --blue-dim: rgba(96, 165, 250, 0.10);
    --blue-medium: rgba(96, 165, 250, 0.18);

    --cyan: #22D3EE;
    --cyan-dim: rgba(34, 211, 238, 0.10);

    --text-primary: #E2E8F0;
    --text-secondary: #8892A4;
    --text-tertiary: #5A6478;
    --text-inverse: #080B12;

    --font-serif: 'Playfair Display', Georgia, serif;
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    --radius-sm: 8px;

    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    --shadow-subtle: 0 1px 3px rgba(0,0,0,0.3);
    --shadow-card: 0 4px 24px rgba(0,0,0,0.4);
    --shadow-elevated: 0 12px 48px rgba(0,0,0,0.5);

    --page-max-width: 1100px;
    --page-padding: 48px;
}

/* ── CUSTOM SCROLLBAR ── */
* {
    scrollbar-width: thin;
    scrollbar-color: var(--mint) var(--obsidian);
}

::-webkit-scrollbar {
    width: 6px;
    height: 6px;
}

::-webkit-scrollbar-track {
    background: var(--obsidian);
}

::-webkit-scrollbar-thumb {
    background: var(--mint);
    border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--mint-hover);
}

/* ── BACK BUTTON ── */
.back-button {
    position: fixed;
    top: 20px;
    right: 20px;
    background: rgba(8, 11, 18, 0.7);
    border: 1px solid var(--card-border);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    color: #ffffff;
    font-size: 1.2em;
    transition: background 0.2s, border-color 0.2s;
    z-index: 1000;
    text-decoration: none;
}

.back-button:hover {
    background: var(--mint-dim);
    border-color: var(--mint);
    color: var(--mint);
}

/* ══════════════════════════════════════════════
   RESET & BASE
   ══════════════════════════════════════════════ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--obsidian);
    color: var(--text-primary);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ══════════════════════════════════════════════
   LANDING PAGE HUB STYLES
   ══════════════════════════════════════════════ */

/* ── HEADER ── */
header {
    position: relative;
    padding: 80px 40px 60px;
    text-align: center;
    overflow: hidden;
    border-bottom: 1px solid var(--card-border);
}

header::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse 70% 60% at 50% 0%, rgba(0, 232, 160, 0.07) 0%, transparent 70%);
    pointer-events: none;
}

.header-logo {
    width: 80px;
    height: auto;
    margin: 0 auto 24px;
    display: block;
}

.header-eyebrow {
    font-family: var(--font-sans);
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--mint);
    margin-bottom: 20px;
}

header h1 {
    font-family: var(--font-serif);
    font-size: clamp(2rem, 5vw, 3.4rem);
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.2;
    margin-bottom: 18px;
}

header h1 em {
    font-style: italic;
    color: var(--mint);
}

header p {
    font-size: 1rem;
    color: var(--text-secondary);
    max-width: 520px;
    margin: 0 auto 36px;
    font-weight: 300;
}

/* ── FILTER TABS ── */
.filter-bar {
    display: flex;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
}

.filter-button {
    font-family: var(--font-sans);
    font-size: 0.8rem;
    font-weight: 500;
    letter-spacing: 0.05em;
    padding: 8px 20px;
    border-radius: 100px;
    border: 1px solid var(--card-border);
    background: transparent;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.filter-button:hover {
    border-color: var(--mint);
    color: var(--mint);
    background: var(--mint-dim);
}

.filter-button.active {
    background: var(--mint);
    border-color: var(--mint);
    color: #080B12;
    font-weight: 600;
}

.filter-button[data-filter="google"] {
    border-color: rgba(0, 232, 160, 0.27);
    color: var(--mint);
}
.filter-button[data-filter="google"]:hover,
.filter-button[data-filter="google"].active {
    background: var(--mint);
    border-color: var(--mint);
    color: #080B12;
}

.filter-button[data-filter="foundation"] {
    border-color: rgba(245, 158, 11, 0.27);
    color: var(--amber);
}
.filter-button[data-filter="foundation"]:hover,
.filter-button[data-filter="foundation"].active {
    background: var(--amber);
    border-color: var(--amber);
    color: #080B12;
}

.filter-button[data-filter="anthropic"] {
    border-color: rgba(255, 107, 107, 0.27);
    color: #FF6B6B;
}
.filter-button[data-filter="anthropic"]:hover,
.filter-button[data-filter="anthropic"].active {
    background: #FF6B6B;
    border-color: #FF6B6B;
    color: #080B12;
}

/* ── MAIN CONTENT ── */
main {
    max-width: 1280px;
    margin: 0 auto;
    padding: 48px 32px 80px;
}

.section-label {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 28px;
}

.section-label span {
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--text-secondary);
}

.section-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--card-border);
}

/* ── PRODUCT GRID ── */
.product-list {
    list-style: none;
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 18px;
}

/* ── CARD ── */
.product-item {
    display: none;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 14px;
    padding: 24px;
    position: relative;
    transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
    overflow: hidden;
}

/* Glow effect */
.product-item::after {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; bottom: 0;
    border-radius: inherit;
    background: radial-gradient(
        600px circle at var(--mouse-x, 0px) var(--mouse-y, 0px),
        rgba(255, 255, 255, 0.05),
        transparent 40%
    );
    opacity: 0;
    transition: opacity 0.5s ease;
    pointer-events: none;
    z-index: 1;
}

.product-item:hover::after {
    opacity: 1;
}

/* Ensure card content is above glow */
.product-item > * {
    position: relative;
    z-index: 2;
}

.product-item.active {
    display: block;
}
.product-item.hidden {
    display: none !important;
}

/* Card header */
.card-header {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    margin-bottom: 18px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--card-border);
}

.product-item h3 {
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
    line-height: 1.3;
}

.badge {
    font-size: 0.65rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    padding: 4px 10px;
    border-radius: 100px;
    white-space: nowrap;
    margin-left: 10px;
    flex-shrink: 0;
    border: 1px solid transparent;
}

/* Action buttons */
.card-actions {
    display: flex;
    gap: 8px;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.download-link,
.infographic-link {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-family: var(--font-sans);
    font-size: 0.75rem;
    font-weight: 500;
    padding: 7px 14px;
    border-radius: 8px;
    text-decoration: none;
    transition: all 0.2s ease;
    letter-spacing: 0.02em;
    background: transparent;
    border: 1px solid var(--card-border);
}

/* GOOGLE THEME (Mint Green) */
.product-item.google::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 2px;
    background: linear-gradient(90deg, transparent, var(--mint), transparent);
    opacity: 0; transition: opacity 0.25s ease;
}
.product-item.google:hover {
    transform: translateY(-4px);
    border-color: rgba(0, 232, 160, 0.25);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4), 0 0 0 1px rgba(0, 232, 160, 0.08);
}
.product-item.google:hover::before { opacity: 1; }
.product-item.google .badge {
    background: var(--mint-dim); color: var(--mint); border-color: rgba(0, 232, 160, 0.2);
}
.product-item.google .download-link, .product-item.google .infographic-link {
    color: var(--mint); border-color: rgba(0, 232, 160, 0.3);
}
.product-item.google .download-link:hover, .product-item.google .infographic-link:hover {
    background: linear-gradient(135deg, transparent, rgba(0, 232, 160, 0.3)); border-color: var(--mint); transform: translateY(-1px);
}

/* FOUNDATION THEME */
.product-item.foundation::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 2px;
    background: linear-gradient(90deg, transparent, var(--amber), transparent);
    opacity: 0; transition: opacity 0.25s ease;
}
.product-item.foundation:hover {
    transform: translateY(-4px);
    border-color: rgba(245, 158, 11, 0.25);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4), 0 0 0 1px rgba(245, 158, 11, 0.08);
}
.product-item.foundation:hover::before { opacity: 1; }
.product-item.foundation .badge {
    background: var(--amber-dim); color: var(--amber); border-color: rgba(245, 158, 11, 0.2);
}
.product-item.foundation .download-link, .product-item.foundation .infographic-link {
    color: var(--amber); border-color: rgba(245, 158, 11, 0.3);
}
.product-item.foundation .download-link:hover, .product-item.foundation .infographic-link:hover {
    background: linear-gradient(135deg, transparent, rgba(245, 158, 11, 0.3)); border-color: var(--amber); transform: translateY(-1px);
}

/* ANTHROPIC THEME (Databricks Inspired) */
.product-item.anthropic::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 2px;
    background: linear-gradient(90deg, transparent, #FF6B6B, transparent);
    opacity: 0; transition: opacity 0.25s ease;
}
.product-item.anthropic:hover {
    transform: translateY(-4px);
    border-color: rgba(255, 107, 107, 0.25);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4), 0 0 0 1px rgba(255, 107, 107, 0.08);
}
.product-item.anthropic:hover::before { opacity: 1; }
.product-item.anthropic .badge {
    background: rgba(255, 107, 107, 0.12); color: #FF8E8E; border-color: rgba(255, 107, 107, 0.2);
}
.product-item.anthropic .download-link, .product-item.anthropic .infographic-link {
    color: #FF6B6B; border-color: rgba(255, 107, 107, 0.3);
}
.product-item.anthropic .download-link:hover, .product-item.anthropic .infographic-link:hover {
    background: linear-gradient(135deg, transparent, rgba(255, 107, 107, 0.3)); border-color: #FF6B6B; transform: translateY(-1px);
}

/* Audio */
.audio-label {
    font-size: 0.68rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-secondary);
    margin-bottom: 6px;
}

.audio-wrapper {
    background: #1E2A3A;
    border: 1px solid #2A3F58;
    border-radius: 10px;
    padding: 6px 8px;
}

audio {
    width: 100%;
    height: 36px;
    border-radius: 6px;
    outline: none;
    filter: invert(1) hue-rotate(150deg) brightness(0.85);
}

/* ── FOOTER ── */
footer {
    border-top: 1px solid var(--card-border);
    padding: 28px 32px;
    text-align: center;
}

footer p {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

footer a {
    color: var(--mint);
    text-decoration: none;
    transition: opacity 0.2s;
}

footer a:hover {
    opacity: 0.75;
}

/* ── PDF OVERLAY ── */
#pdf-container {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(6px);
    z-index: 1000;
}

#pdf-inner {
    position: relative;
    width: 80%;
    height: 90%;
    margin: 5% auto;
    background: #0F1320;
    border: 1px solid var(--card-border);
    border-radius: 14px;
    padding: 1em;
    overflow: auto;
}

#pdf-close {
    position: absolute;
    top: 12px;
    right: 16px;
    background: none;
    border: none;
    font-size: 1.6em;
    cursor: pointer;
    color: var(--mint);
    transition: color 0.2s;
}

#pdf-close:hover {
    color: var(--mint);
}

/* ── INFOGRAPHIC OVERLAY ── */
#infographic-container {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.85);
    backdrop-filter: blur(6px);
    z-index: 1000;
}

#infographic-inner {
    position: relative;
    width: 80%;
    height: 90%;
    margin: 5% auto;
    background: #0F1320;
    border: 1px solid var(--card-border);
    border-radius: 14px;
    padding: 1em;
    overflow: auto;
    display: flex;
    justify-content: center;
    align-items: center;
}

#infographic-inner img {
    max-width: 100%;
    max-height: 100%;
    object-fit: contain;
}

#infographic-close {
    position: absolute;
    top: 12px;
    right: 16px;
    background: none;
    border: none;
    font-size: 1.6em;
    cursor: pointer;
    color: var(--mint);
    transition: color 0.2s;
    z-index: 1001;
}

#infographic-close:hover {
    color: var(--mint);
}

@media (max-width: 768px) {
    header { padding: 60px 24px 48px; }
    main { padding: 32px 16px 60px; }
    .product-list { grid-template-columns: 1fr; }
}

/* ══════════════════════════════════════════════
   PAGE WRAPPER
   ══════════════════════════════════════════════ */
.page-wrapper {
    max-width: var(--page-max-width);
    margin: 0 auto;
    padding: var(--page-padding);
}

/* ══════════════════════════════════════════════
   COVER / HERO SECTION
   ══════════════════════════════════════════════ */
.cover {
    position: relative;
    padding: 64px 48px;
    border: 1px solid var(--card-border);
    border-radius: var(--radius-xl);
    background: var(--card-bg);
    margin-bottom: 48px;
    overflow: hidden;
    page-break-after: avoid;
}

.cover::before {
    content: '';
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 80% 50% at 20% 0%, rgba(184, 130, 255, 0.06) 0%, transparent 60%),
        radial-gradient(ellipse 60% 50% at 80% 100%, rgba(0, 232, 160, 0.04) 0%, transparent 60%);
    pointer-events: none;
}

.cover::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--purple), var(--mint), var(--amber));
    border-radius: var(--radius-xl) var(--radius-xl) 0 0;
}

.cover-grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(255,255,255,0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255,255,255,0.02) 1px, transparent 1px);
    background-size: 40px 40px;
    pointer-events: none;
    mask-image: radial-gradient(ellipse 70% 70% at 50% 50%, black, transparent);
}

.cover-content {
    position: relative;
    z-index: 1;
}

.cover-eyebrow {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--mint);
    margin-bottom: 20px;
    padding: 6px 14px;
    background: var(--mint-dim);
    border: 1px solid rgba(0, 232, 160, 0.15);
    border-radius: 100px;
}

.cover-eyebrow i {
    font-size: 0.65rem;
}

.cover h1 {
    font-family: var(--font-serif);
    font-size: clamp(2.2rem, 5vw, 3.2rem);
    font-weight: 700;
    line-height: 1.15;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.cover h1 em {
    font-style: italic;
    color: var(--mint);
}

.cover-subtitle {
    font-size: 1.05rem;
    font-weight: 300;
    color: var(--text-secondary);
    max-width: 600px;
    margin-bottom: 32px;
    line-height: 1.7;
}

.cover-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 24px;
    padding-top: 24px;
    border-top: 1px solid var(--card-border);
}

.cover-meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.cover-meta-item i {
    color: var(--mint);
    font-size: 0.75rem;
    width: 16px;
    text-align: center;
}

.cover-meta-item strong {
    color: var(--text-primary);
    font-weight: 600;
}

/* ══════════════════════════════════════════════
   TABLE OF CONTENTS
   ══════════════════════════════════════════════ */
.toc {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 32px;
    margin-bottom: 48px;
    page-break-after: avoid;
}

.toc-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--card-border);
}

.toc-header i {
    color: var(--mint);
    font-size: 1rem;
}

.toc-header h2 {
    font-family: var(--font-sans);
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: var(--text-secondary);
}

.toc-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 8px 32px;
}

.toc-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    text-decoration: none;
    color: var(--text-primary);
    font-size: 0.88rem;
    font-weight: 400;
    transition: all 0.2s ease;
    border: 1px solid transparent;
}

.toc-item:hover {
    background: var(--mint-dim);
    border-color: rgba(0, 232, 160, 0.12);
    color: var(--mint);
}

.toc-number {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--text-tertiary);
    min-width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--surface-raised);
    border-radius: 6px;
    border: 1px solid var(--card-border);
}

.toc-item:hover .toc-number {
    color: var(--mint);
    border-color: rgba(0, 232, 160, 0.2);
    background: var(--mint-dim);
}

.toc-dots {
    flex: 1;
    border-bottom: 1px dotted var(--card-border);
    min-width: 20px;
    margin: 0 4px;
    align-self: flex-end;
    margin-bottom: 4px;
}

/* ══════════════════════════════════════════════
   SECTION DIVIDER
   ══════════════════════════════════════════════ */
.section-divider {
    display: flex;
    align-items: center;
    gap: 16px;
    margin: 56px 0 32px;
    page-break-after: avoid;
}

.section-divider-number {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--mint);
    padding: 6px 12px;
    background: var(--mint-dim);
    border: 1px solid rgba(0, 232, 160, 0.15);
    border-radius: 100px;
    letter-spacing: 0.05em;
}

.section-divider h2 {
    font-family: var(--font-serif);
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--text-primary);
    white-space: nowrap;
}

.section-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: linear-gradient(90deg, var(--card-border), transparent);
}

/* ══════════════════════════════════════════════
   CONTENT BLOCKS
   ══════════════════════════════════════════════ */

/* --- Key Concept Card --- */
.concept-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 28px 32px;
    margin-bottom: 20px;
    position: relative;
    overflow: hidden;
    page-break-inside: avoid;
    transition: border-color 0.25s ease, box-shadow 0.25s ease;
}

.concept-card:hover {
    border-color: rgba(0, 232, 160, 0.2);
    box-shadow: var(--shadow-card);
}

.concept-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    width: 3px;
    border-radius: 3px 0 0 3px;
}

.concept-card.accent-mint::before { background: var(--mint); }
.concept-card.accent-purple::before { background: var(--purple); }
.concept-card.accent-amber::before { background: var(--amber); }
.concept-card.accent-blue::before { background: var(--blue); }
.concept-card.accent-coral::before { background: var(--coral); }
.concept-card.accent-cyan::before { background: var(--cyan); }
.concept-card.accent-pink::before { background: var(--pink); }

.concept-card h3 {
    font-family: var(--font-sans);
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.concept-card h3 .icon-badge {
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 8px;
    font-size: 0.8rem;
    flex-shrink: 0;
}

.concept-card.accent-mint h3 .icon-badge {
    background: var(--mint-dim);
    color: var(--mint);
    border: 1px solid rgba(0, 232, 160, 0.15);
}

.concept-card.accent-purple h3 .icon-badge {
    background: var(--purple-dim);
    color: var(--purple);
    border: 1px solid rgba(184, 130, 255, 0.15);
}

.concept-card.accent-amber h3 .icon-badge {
    background: var(--amber-dim);
    color: var(--amber);
    border: 1px solid rgba(245, 158, 11, 0.15);
}

.concept-card.accent-blue h3 .icon-badge {
    background: var(--blue-dim);
    color: var(--blue);
    border: 1px solid rgba(96, 165, 250, 0.15);
}

.concept-card.accent-coral h3 .icon-badge {
    background: var(--coral-dim);
    color: var(--coral);
    border: 1px solid rgba(255, 107, 107, 0.15);
}

.concept-card.accent-cyan h3 .icon-badge {
    background: var(--cyan-dim);
    color: var(--cyan);
    border: 1px solid rgba(34, 211, 238, 0.15);
}

.concept-card.accent-pink h3 .icon-badge {
    background: var(--pink-dim);
    color: var(--pink);
    border: 1px solid rgba(244, 114, 182, 0.15);
}

.concept-card p,
.concept-card li {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.75;
}

.concept-card ul {
    list-style: none;
    margin-top: 8px;
}

.concept-card ul li {
    padding: 5px 0;
    padding-left: 20px;
    position: relative;
}

.concept-card ul li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--mint);
    font-size: 0.8rem;
}

.concept-card.accent-purple ul li::before { color: var(--purple); }
.concept-card.accent-amber ul li::before { color: var(--amber); }
.concept-card.accent-blue ul li::before { color: var(--blue); }
.concept-card.accent-coral ul li::before { color: var(--coral); }
.concept-card.accent-cyan ul li::before { color: var(--cyan); }
.concept-card.accent-pink ul li::before { color: var(--pink); }

/* --- Definition / Glossary Block --- */
.definition-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.definition-item {
    background: var(--surface-raised);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    padding: 20px 24px;
    page-break-inside: avoid;
    transition: border-color 0.2s ease;
}

.definition-item:hover {
    border-color: rgba(184, 130, 255, 0.2);
}

.definition-item dt {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--mint);
    margin-bottom: 6px;
    letter-spacing: 0.02em;
}

.definition-item dd {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

/* --- Highlight / Callout Box --- */
.callout {
    display: flex;
    gap: 16px;
    padding: 20px 24px;
    border-radius: var(--radius-md);
    margin-bottom: 24px;
    page-break-inside: avoid;
    border: 1px solid;
}

.callout-icon {
    flex-shrink: 0;
    width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 10px;
    font-size: 0.9rem;
}

.callout-content h4 {
    font-size: 0.82rem;
    font-weight: 600;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    margin-bottom: 6px;
}

.callout-content p {
    font-size: 0.87rem;
    line-height: 1.7;
}

/* Callout: Exam Tip (Mint) */
.callout.tip {
    background: var(--mint-dim);
    border-color: rgba(0, 232, 160, 0.15);
}
.callout.tip .callout-icon {
    background: rgba(0, 232, 160, 0.15);
    color: var(--mint);
}
.callout.tip .callout-content h4 { color: var(--mint); }
.callout.tip .callout-content p { color: rgba(0, 232, 160, 0.75); }

/* Callout: Warning (Amber) */
.callout.warning {
    background: var(--amber-dim);
    border-color: rgba(245, 158, 11, 0.15);
}
.callout.warning .callout-icon {
    background: rgba(245, 158, 11, 0.15);
    color: var(--amber);
}
.callout.warning .callout-content h4 { color: var(--amber); }
.callout.warning .callout-content p { color: rgba(245, 158, 11, 0.75); }

/* Callout: Important (Purple) */
.callout.important {
    background: var(--purple-dim);
    border-color: rgba(184, 130, 255, 0.15);
}
.callout.important .callout-icon {
    background: rgba(184, 130, 255, 0.15);
    color: var(--purple);
}
.callout.important .callout-content h4 { color: var(--purple); }
.callout.important .callout-content p { color: rgba(184, 130, 255, 0.75); }

/* Callout: Key Fact (Blue) */
.callout.info {
    background: var(--blue-dim);
    border-color: rgba(96, 165, 250, 0.15);
}
.callout.info .callout-icon {
    background: rgba(96, 165, 250, 0.15);
    color: var(--blue);
}
.callout.info .callout-content h4 { color: var(--blue); }
.callout.info .callout-content p { color: rgba(96, 165, 250, 0.75); }

/* --- Comparison Table --- */
.comparison-table-wrapper {
    overflow-x: auto;
    margin-bottom: 24px;
    border-radius: var(--radius-md);
    border: 1px solid var(--card-border);
    background: var(--card-bg);
}

.comparison-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
}

.comparison-table thead th {
    background: var(--surface-raised);
    padding: 14px 20px;
    text-align: left;
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--card-border);
    position: sticky;
    top: 0;
}

.comparison-table thead th:first-child {
    color: var(--purple);
}

.comparison-table tbody td {
    padding: 12px 20px;
    border-bottom: 1px solid var(--card-border);
    color: var(--text-secondary);
    vertical-align: top;
}

.comparison-table tbody tr:last-child td {
    border-bottom: none;
}

.comparison-table tbody tr:hover td {
    background: rgba(184, 130, 255, 0.03);
}

.comparison-table tbody td:first-child {
    font-weight: 500;
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

.table-check {
    color: var(--mint);
}

.table-cross {
    color: var(--coral);
    opacity: 0.6;
}

/* --- Versus Block --- */
.versus-block {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 0;
    margin-bottom: 24px;
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    page-break-inside: avoid;
}

.versus-side { padding: 24px 28px; background: var(--card-bg); }

.versus-side h4 {
    font-size: 0.88rem;
    font-weight: 600;
    margin-bottom: 12px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.versus-side.left h4 { color: var(--amber); }
.versus-side.right h4 { color: var(--purple); }

.versus-side ul { list-style: none; }
.versus-side ul li {
    font-size: 0.84rem;
    color: var(--text-secondary);
    padding: 4px 0 4px 16px;
    position: relative;
    line-height: 1.6;
}

.versus-side.left ul li::before { content: '▸'; position: absolute; left: 0; color: var(--amber); font-size: 0.75rem; }
.versus-side.right ul li::before { content: '▸'; position: absolute; left: 0; color: var(--purple); font-size: 0.75rem; }

.versus-divider {
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--surface-raised);
    border-left: 1px solid var(--card-border);
    border-right: 1px solid var(--card-border);
    padding: 0 16px;
    font-family: var(--font-serif);
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-tertiary);
}

@media (max-width: 640px) {
    .versus-block { grid-template-columns: 1fr; }
    .versus-divider {
        border-left: none; border-right: none;
        border-top: 1px solid var(--card-border);
        border-bottom: 1px solid var(--card-border);
        padding: 10px;
    }
}

/* --- Code / Command Block --- */
.code-block {
    background: var(--surface-sunken);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    margin-bottom: 24px;
    overflow: hidden;
    page-break-inside: avoid;
}

.code-block-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 18px;
    background: var(--surface-raised);
    border-bottom: 1px solid var(--card-border);
}

.code-block-lang {
    font-family: var(--font-mono);
    font-size: 0.68rem;
    font-weight: 500;
    color: var(--text-tertiary);
    letter-spacing: 0.08em;
    text-transform: uppercase;
}

.code-block-dots {
    display: flex;
    gap: 6px;
}

.code-block-dots span {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--card-border);
}

.code-block-dots span:first-child { background: #FF5F57; }
.code-block-dots span:nth-child(2) { background: #FFBD2E; }
.code-block-dots span:nth-child(3) { background: #28CA41; }

.code-block pre {
    padding: 18px 22px;
    overflow-x: auto;
    font-family: var(--font-mono);
    font-size: 0.82rem;
    line-height: 1.7;
    color: var(--text-secondary);
}

.code-block pre .keyword { color: var(--purple); }
.code-block pre .function { color: var(--mint); }
.code-block pre .string { color: var(--amber); }
.code-block pre .comment { color: var(--text-tertiary); font-style: italic; }
.code-block pre .variable { color: var(--blue); }
.code-block pre .operator { color: var(--coral); }

/* --- Formula / Equation Block --- */
.formula-block {
    background: var(--surface-raised);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    padding: 24px 28px;
    margin-bottom: 24px;
    text-align: center;
    page-break-inside: avoid;
}

.formula-label {
    font-size: 0.68rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--text-tertiary);
    margin-bottom: 12px;
}

.formula {
    font-family: var(--font-mono);
    font-size: 1.1rem;
    color: var(--mint);
    padding: 12px;
    background: var(--mint-dim);
    border: 1px solid rgba(0, 232, 160, 0.12);
    border-radius: var(--radius-sm);
    display: inline-block;
    letter-spacing: 0.03em;
}

.formula-description {
    font-size: 0.82rem;
    color: var(--text-tertiary);
    margin-top: 10px;
}

/* --- Step-by-step / Process Flow --- */
.process-flow {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 12px;
    margin-bottom: 24px;
}

.process-step {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    padding: 20px;
    text-align: center;
    position: relative;
    page-break-inside: avoid;
    transition: border-color 0.2s ease, transform 0.2s ease;
}

.process-step:hover {
    border-color: rgba(0, 232, 160, 0.2);
    transform: translateY(-2px);
}

.process-step-number {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    font-weight: 600;
    color: var(--mint);
    background: var(--mint-dim);
    border: 1px solid rgba(0, 232, 160, 0.15);
    border-radius: 100px;
    padding: 3px 10px;
    display: inline-block;
    margin-bottom: 12px;
    letter-spacing: 0.1em;
}

.process-step h4 {
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 6px;
}

.process-step p {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.process-arrow {
    display: none;
}

@media (min-width: 700px) {
    .process-step:not(:last-child)::after {
        content: '→';
        position: absolute;
        right: -16px;
        top: 50%;
        transform: translateY(-50%);
        color: var(--text-tertiary);
        font-size: 1.1rem;
        z-index: 1;
    }
}

/* --- Diagram / Architecture Block --- */
.diagram-block {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 32px;
    margin-bottom: 24px;
    page-break-inside: avoid;
}

.diagram-title {
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--text-tertiary);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.diagram-title i {
    color: var(--purple);
}

.architecture-flow {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    flex-wrap: wrap;
    padding: 16px 0;
}

.arch-node {
    padding: 12px 20px;
    border-radius: var(--radius-sm);
    font-size: 0.78rem;
    font-weight: 500;
    text-align: center;
    border: 1px solid;
    min-width: 120px;
}

.arch-node.input {
    background: var(--blue-dim);
    border-color: rgba(96, 165, 250, 0.2);
    color: var(--blue);
}

.arch-node.process {
    background: var(--purple-dim);
    border-color: rgba(184, 130, 255, 0.2);
    color: var(--purple);
}

.arch-node.output {
    background: var(--mint-dim);
    border-color: rgba(0, 232, 160, 0.2);
    color: var(--mint);
}

.arch-node.storage {
    background: var(--amber-dim);
    border-color: rgba(245, 158, 11, 0.2);
    color: var(--amber);
}

.arch-arrow {
    color: var(--text-tertiary);
    font-size: 1.2rem;
}

/* --- Summary / Key Takeaways --- */
.summary-block {
    background: linear-gradient(135deg, rgba(184, 130, 255, 0.05), rgba(0, 232, 160, 0.05));
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    padding: 32px;
    margin-bottom: 24px;
    page-break-inside: avoid;
}

.summary-block h3 {
    font-family: var(--font-sans);
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--purple);
    margin-bottom: 18px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.summary-block h3 i {
    font-size: 0.85rem;
}

.summary-list {
    list-style: none;
    display: grid;
    gap: 10px;
}

.summary-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.65;
}

.summary-list li i {
    color: var(--mint);
    font-size: 0.7rem;
    margin-top: 6px;
    flex-shrink: 0;
}

/* --- Quiz / Self-Test Block --- */
.quiz-block {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-lg);
    overflow: hidden;
    margin-bottom: 24px;
    page-break-inside: avoid;
}

.quiz-header {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 16px 24px;
    background: var(--surface-raised);
    border-bottom: 1px solid var(--card-border);
}

.quiz-header i {
    color: var(--amber);
    font-size: 0.9rem;
}

.quiz-header h3 {
    font-size: 0.72rem;
    font-weight: 600;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--text-secondary);
}

.quiz-body {
    padding: 24px;
}

.quiz-question {
    margin-bottom: 20px;
}

.quiz-question:last-child {
    margin-bottom: 0;
}

.quiz-question p {
    font-size: 0.88rem;
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: 10px;
    display: flex;
    gap: 8px;
}

.quiz-question p .q-num {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    color: var(--amber);
    font-weight: 600;
    flex-shrink: 0;
}

.quiz-answer {
    font-size: 0.82rem;
    color: var(--text-tertiary);
    padding: 10px 16px;
    background: var(--surface-raised);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-sm);
    margin-left: 28px;
    cursor: pointer;
    transition: all 0.2s ease;
    user-select: none;
}

.quiz-answer:hover,
.quiz-answer.revealed {
    background: var(--mint-dim);
    border-color: rgba(0, 232, 160, 0.2);
    color: var(--mint);
}

.quiz-answer::before {
    content: 'Click to reveal answer';
    font-size: 0.7rem;
    font-weight: 500;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    opacity: 0.6;
}

.quiz-answer.revealed::before {
    content: 'Answer: ';
    opacity: 1;
    font-weight: 600;
}

.quiz-answer .answer-text {
    display: none;
}

.quiz-answer.revealed .answer-text {
    display: inline;
}

/* --- Inline Highlight Tags --- */
.tag {
    display: inline-block;
    font-family: var(--font-mono);
    font-size: 0.72rem;
    font-weight: 500;
    padding: 2px 8px;
    border-radius: 4px;
    letter-spacing: 0.02em;
}

.tag.mint { background: var(--mint-dim); color: var(--mint); border: 1px solid rgba(0,232,160,0.15); }
.tag.purple { background: var(--purple-dim); color: var(--purple); border: 1px solid rgba(184,130,255,0.15); }
.tag.amber { background: var(--amber-dim); color: var(--amber); border: 1px solid rgba(245,158,11,0.15); }
.tag.blue { background: var(--blue-dim); color: var(--blue); border: 1px solid rgba(96,165,250,0.15); }

/* --- Stats / Metrics Row --- */
.stats-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 12px;
    margin-bottom: 24px;
}

.stat-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: var(--radius-md);
    padding: 20px;
    text-align: center;
    page-break-inside: avoid;
}

.stat-card .stat-value {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.stat-card .stat-label {
    font-size: 0.72rem;
    font-weight: 500;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--text-tertiary);
}

.stat-card.mint .stat-value { color: var(--mint); }
.stat-card.purple .stat-value { color: var(--purple); }
.stat-card.amber .stat-value { color: var(--amber); }
.stat-card.blue .stat-value { color: var(--blue); }

/* --- Prose / Body Text --- */
.prose {
    margin-bottom: 24px;
}

.prose p {
    font-size: 0.92rem;
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 14px;
}

.prose p:last-child {
    margin-bottom: 0;
}

.prose strong {
    color: var(--text-primary);
    font-weight: 600;
}

.prose code {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    background: var(--surface-raised);
    border: 1px solid var(--card-border);
    padding: 2px 7px;
    border-radius: 4px;
    color: var(--mint);
}

.prose a {
    color: var(--purple);
    text-decoration: none;
    border-bottom: 1px dotted rgba(184, 130, 255, 0.3);
    transition: border-color 0.2s;
}

.prose a:hover {
    border-color: var(--purple);
}

/* --- Two-Column Layout --- */
.two-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

/* --- Three-Column Layout --- */
.three-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

/* --- Checklist Block --- */
.checklist {
    list-style: none;
    margin-bottom: 24px;
}

.checklist li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 10px 0;
    border-bottom: 1px solid var(--card-border);
    font-size: 0.88rem;
    color: var(--text-secondary);
}

.checklist li:last-child {
    border-bottom: none;
}

.checklist li .check-icon {
    width: 20px;
    height: 20px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    font-size: 0.6rem;
    margin-top: 2px;
    background: var(--mint-dim);
    color: var(--mint);
    border: 1px solid rgba(0, 232, 160, 0.2);
}

/* --- Numbered Steps --- */
.numbered-steps {
    counter-reset: step-counter;
    list-style: none;
    margin-bottom: 24px;
}

.numbered-steps li {
    counter-increment: step-counter;
    display: flex;
    align-items: flex-start;
    gap: 16px;
    padding: 16px 0;
    border-bottom: 1px solid var(--card-border);
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.7;
}

.numbered-steps li:last-child { border-bottom: none; }

.numbered-steps li::before {
    content: counter(step-counter, decimal-leading-zero);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--purple);
    background: var(--purple-dim);
    border: 1px solid rgba(184,130,255,0.15);
    border-radius: 8px;
    min-width: 36px;
    height: 36px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
    margin-top: 2px;
}

.numbered-steps li strong { color: var(--text-primary); }

/* ══════════════════════════════════════════════
   PROGRESS TRACKER (for certification path)
   ══════════════════════════════════════════════ */
.progress-bar-wrapper {
    margin-bottom: 24px;
}

.progress-bar-label {
    display: flex;
    justify-content: space-between;
    font-size: 0.78rem;
    margin-bottom: 8px;
}

.progress-bar-label span:first-child {
    font-weight: 500;
    color: var(--text-primary);
}

.progress-bar-label span:last-child {
    font-family: var(--font-mono);
    font-weight: 500;
    color: var(--mint);
}

.progress-bar {
    height: 6px;
    background: var(--surface-raised);
    border-radius: 100px;
    overflow: hidden;
    border: 1px solid var(--card-border);
}

.progress-bar-fill {
    height: 100%;
    border-radius: 100px;
    background: linear-gradient(90deg, var(--purple), var(--mint));
    transition: width 0.4s ease;
}

/* ══════════════════════════════════════════════
   FOOTER
   ══════════════════════════════════════════════ */
.page-footer {
    border-top: 1px solid var(--card-border);
    padding: 32px 0 16px;
    margin-top: 48px;
    text-align: center;
}

.page-footer p {
    font-size: 0.78rem;
    color: var(--text-tertiary);
    margin-bottom: 4px;
}

.page-footer a {
    color: var(--mint);
    text-decoration: none;
}

.page-footer a:hover {
    opacity: 0.8;
}

/* ══════════════════════════════════════════════
   BACK TO TOP BUTTON
   ══════════════════════════════════════════════ */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 44px;
    height: 44px;
    border-radius: 12px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--mint);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9rem;
    transition: all 0.2s ease;
    opacity: 0;
    pointer-events: none;
    z-index: 100;
    box-shadow: var(--shadow-card);
}

.back-to-top.visible {
    opacity: 1;
    pointer-events: auto;
}

.back-to-top:hover {
    border-color: var(--mint);
    color: var(--mint);
    background: var(--mint-dim);
    transform: translateY(-2px);
}

/* ══════════════════════════════════════════════
   PRINT / PDF STYLES
   ══════════════════════════════════════════════ */
@media print {
    :root {
        --obsidian: #ffffff;
        --card-bg: #f8f9fb;
        --card-bg-alt: #f3f4f6;
        --card-border: #e2e5ea;
        --surface-raised: #eef0f4;
        --surface-sunken: #f0f2f5;

        --mint: #059669;
        --mint-dim: rgba(5, 150, 105, 0.08);
        --purple: #7C3AED;
        --purple-dim: rgba(124, 58, 237, 0.08);
        --amber: #B45309;
        --amber-dim: rgba(180, 83, 9, 0.08);
        --coral: #DC2626;
        --coral-dim: rgba(220, 38, 38, 0.08);
        --blue: #2563EB;
        --blue-dim: rgba(37, 99, 235, 0.08);
        --cyan: #0891B2;
        --cyan-dim: rgba(8, 145, 178, 0.08);

        --text-primary: #111827;
        --text-secondary: #4B5563;
        --text-tertiary: #9CA3AF;
        --text-inverse: #ffffff;
    }

    body {
        background: white;
        color: var(--text-primary);
        font-size: 11pt;
        line-height: 1.5;
    }

    .page-wrapper {
        max-width: 100%;
        padding: 0;
    }

    .cover {
        padding: 40px 32px;
        box-shadow: none;
        border: 2px solid var(--card-border);
    }

    .cover::before,
    .cover-grid {
        display: none;
    }

    .cover::after {
        height: 4px;
    }

    .back-to-top {
        display: none !important;
    }

    .concept-card,
    .definition-item,
    .callout,
    .process-step,
    .quiz-block,
    .summary-block,
    .formula-block,
    .stat-card,
    .code-block {
        break-inside: avoid;
        page-break-inside: avoid;
        box-shadow: none;
    }

    .section-divider {
        break-after: avoid;
        page-break-after: avoid;
    }

    .quiz-answer .answer-text {
        display: inline !important;
    }

    .quiz-answer::before {
        content: 'Answer: ' !important;
        font-weight: 600;
        opacity: 1;
    }

    .toc-item:hover,
    .concept-card:hover,
    .definition-item:hover,
    .process-step:hover {
        transform: none;
        border-color: var(--card-border);
    }

    a[href]::after {
        content: none;
    }

    .comparison-table thead th {
        background: var(--surface-raised) !important;
        -webkit-print-color-adjust: exact;
        print-color-adjust: exact;
    }

    @page {
        margin: 1.5cm 2cm;
        size: A4;
    }
}

/* ══════════════════════════════════════════════
   RESPONSIVE
   ══════════════════════════════════════════════ */
@media (max-width: 768px) {
    .page-wrapper {
        padding: 24px 16px;
    }

    .cover {
        padding: 40px 24px;
    }

    .cover-meta {
        flex-direction: column;
        gap: 12px;
    }

    .section-divider h2 {
        font-size: 1.3rem;
    }

    .concept-card {
        padding: 20px 22px;
    }

    .process-flow {
        grid-template-columns: 1fr;
    }

    .process-step:not(:last-child)::after {
        display: none;
    }

    .architecture-flow {
        flex-direction: column;
    }

    .arch-arrow {
        transform: rotate(90deg);
    }
}