/* ========================================
   The Knowing Problem
   Editorial Luxury Design System
   ======================================== */

:root {
    /* Colors - Light mode with blue accent */
    --color-bg: #F8F7F4;
    --color-bg-warm: #F0F4F7;
    --color-bg-alt: #E8EEF2;
    --color-text: #1C1C1C;
    --color-text-secondary: #4A5568;
    --color-text-tertiary: #718096;
    --color-accent: #2B5B84;
    --color-accent-light: #3A7CA5;
    --color-border: #D4DEE7;
    --color-border-dark: #B8C9D9;
    
    /* Typography */
    --font-display: 'Cormorant Garamond', Georgia, serif;
    --font-body: 'Source Serif 4', Georgia, serif;
    --font-ui: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    
    /* Spacing */
    --space-xs: 0.5rem;
    --space-sm: 1rem;
    --space-md: 2rem;
    --space-lg: 3rem;
    --space-xl: 5rem;
    --space-2xl: 7rem;
    
    /* Layout */
    --max-width-narrow: 600px;
    --max-width-content: 820px;
    --max-width-wide: 1200px;
    
    /* Transitions */
    --ease-out-expo: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --duration-fast: 0.2s;
    --duration-medium: 0.4s;
    --duration-slow: 0.8s;
}

/* Dark mode */
@media (prefers-color-scheme: dark) {
    :root {
        --color-bg: #121820;
        --color-bg-warm: #1A2332;
        --color-bg-alt: #232D3B;
        --color-text: #E8EEF2;
        --color-text-secondary: #A0AEC0;
        --color-text-tertiary: #718096;
        --color-accent: #5B9BD5;
        --color-accent-light: #7BB3E0;
        --color-border: #2D3A4D;
        --color-border-dark: #3D4F66;
    }
    
    .grain-overlay {
        opacity: 0.015;
    }
}

/* Manual dark mode toggle support */
[data-theme="dark"] {
    --color-bg: #121820;
    --color-bg-warm: #1A2332;
    --color-bg-alt: #232D3B;
    --color-text: #E8EEF2;
    --color-text-secondary: #A0AEC0;
    --color-text-tertiary: #718096;
    --color-accent: #5B9BD5;
    --color-accent-light: #7BB3E0;
    --color-border: #2D3A4D;
    --color-border-dark: #3D4F66;
}

[data-theme="dark"] .grain-overlay {
    opacity: 0.015;
}

[data-theme="light"] {
    --color-bg: #F8F7F4;
    --color-bg-warm: #F0F4F7;
    --color-bg-alt: #E8EEF2;
    --color-text: #1C1C1C;
    --color-text-secondary: #4A5568;
    --color-text-tertiary: #718096;
    --color-accent: #2B5B84;
    --color-accent-light: #3A7CA5;
    --color-border: #D4DEE7;
    --color-border-dark: #B8C9D9;
}

/* ========================================
   Reset & Base
   ======================================== */

*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 18px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-body);
    font-size: 1rem;
    line-height: 1.75;
    color: var(--color-text);
    background-color: var(--color-bg);
    overflow-x: hidden;
}

::selection {
    background-color: var(--color-accent);
    color: white;
}

/* Grain overlay for texture */
.grain-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1000;
    opacity: 0.03;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
}

/* ========================================
   Site Header
   ======================================== */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    padding: var(--space-md) var(--space-lg);
    mix-blend-mode: difference;
}

.header-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: var(--max-width-wide);
    margin: 0 auto;
}

.header-label {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: white;
}

.header-download {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: white;
    text-decoration: none;
    transition: opacity var(--duration-fast) ease;
}

.header-download:hover {
    opacity: 0.6;
}

/* ========================================
   Landing Page - Hero
   ======================================== */

.landing-main {
    position: relative;
}

.hero {
    min-height: 85vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: var(--space-xl) var(--space-lg);
    position: relative;
}

.hero-content {
    text-align: center;
}

.hero-title {
    font-family: var(--font-display);
    font-size: clamp(3.5rem, 12vw, 9rem);
    font-weight: 400;
    line-height: 0.95;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-md);
}

.title-line {
    display: block;
    opacity: 0;
    transform: translateY(40px);
    animation: revealUp 1s var(--ease-out-expo) forwards;
}

.title-line:nth-child(1) {
    animation-delay: 0.2s;
}

.title-line:nth-child(2) {
    animation-delay: 0.35s;
}

@keyframes revealUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-subtitle {
    font-family: var(--font-ui);
    font-size: 0.85rem;
    font-weight: 400;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-text-secondary);
    opacity: 0;
    animation: fadeIn 1s var(--ease-out-quad) 0.6s forwards;
}

@keyframes fadeIn {
    to {
        opacity: 1;
    }
}

.hero-scroll-indicator {
    position: absolute;
    bottom: var(--space-lg);
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-sm);
    opacity: 0;
    animation: fadeIn 1s var(--ease-out-quad) 1s forwards;
}

.hero-scroll-indicator span {
    font-family: var(--font-ui);
    font-size: 0.65rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--color-text-tertiary);
}

.scroll-line {
    width: 1px;
    height: 60px;
    background: linear-gradient(to bottom, var(--color-text-tertiary), transparent);
    animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
    0%, 100% { opacity: 0.3; transform: scaleY(1); }
    50% { opacity: 1; transform: scaleY(1.1); }
}

/* ========================================
   Landing Page - Premise Sections
   ======================================== */

.premise {
    padding: var(--space-xl) var(--space-lg);
    border-top: 1px solid var(--color-border);
}

.premise-inner {
    max-width: var(--max-width-content);
    margin: 0 auto;
    display: grid;
    grid-template-columns: 80px 1fr;
    gap: var(--space-lg);
}

.premise-number {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    color: var(--color-text-tertiary);
    padding-top: 0.5rem;
}

.premise-content p {
    margin-bottom: var(--space-sm);
}

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

.premise-lead {
    font-size: 1.5rem;
    line-height: 1.5;
    margin-bottom: var(--space-md) !important;
}

/* Scroll animations */
[data-animate] {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity var(--duration-slow) var(--ease-out-quad),
                transform var(--duration-slow) var(--ease-out-quad);
}

[data-animate].visible {
    opacity: 1;
    transform: translateY(0);
}

/* ========================================
   Landing Page - CTA Section
   ======================================== */

.cta-section {
    padding: var(--space-xl) var(--space-lg);
    text-align: center;
    border-top: 1px solid var(--color-border);
}

.cta-primary {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    font-family: var(--font-display);
    font-size: 1.25rem;
    color: var(--color-text);
    text-decoration: none;
    padding: var(--space-sm) var(--space-md);
    border: 1px solid var(--color-text);
    transition: all var(--duration-medium) var(--ease-out-expo);
}

.cta-primary:hover {
    background-color: var(--color-text);
    color: var(--color-bg);
    padding-right: var(--space-lg);
}

.cta-primary:hover .cta-arrow {
    transform: translateX(8px);
}

.cta-arrow {
    transition: transform var(--duration-medium) var(--ease-out-expo);
}

.cta-note {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
    margin-top: var(--space-md);
    letter-spacing: 0.05em;
}

/* ========================================
   Landing Page - Table of Contents
   ======================================== */

.toc-section {
    padding: var(--space-xl) var(--space-lg);
    background-color: var(--color-bg-warm);
    border-top: 1px solid var(--color-border);
}

.toc-header {
    max-width: var(--max-width-wide);
    margin: 0 auto var(--space-xl);
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    padding-bottom: var(--space-md);
    border-bottom: 1px solid var(--color-border-dark);
}

.toc-label {
    font-family: var(--font-display);
    font-size: 1.75rem;
}

.toc-count {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-tertiary);
}

.toc-grid {
    max-width: var(--max-width-wide);
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-lg) var(--space-xl);
}

.toc-part {
    padding-bottom: var(--space-lg);
}

.toc-part-header {
    display: flex;
    align-items: baseline;
    gap: var(--space-sm);
    margin-bottom: var(--space-md);
}

.toc-part-number {
    font-family: var(--font-ui);
    font-size: 0.65rem;
    font-weight: 500;
    color: var(--color-text-tertiary);
}

.toc-part-title {
    font-family: var(--font-display);
    font-size: 1.125rem;
    font-weight: 500;
}

.toc-chapters {
    list-style: none;
    counter-reset: none;
}

.toc-chapters li {
    padding: 0.4rem 0;
    border-bottom: 1px solid var(--color-border);
}

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

.toc-chapters a {
    font-family: var(--font-ui);
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    transition: color var(--duration-fast) ease;
}

.toc-chapters a:hover {
    color: var(--color-text);
}

/* ========================================
   Landing Page - Closing
   ======================================== */

.closing {
    padding: var(--space-xl) var(--space-lg);
    text-align: center;
    border-top: 1px solid var(--color-border);
}

.closing-quote {
    max-width: var(--max-width-narrow);
    margin: 0 auto var(--space-xl);
}

.closing-quote p {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-style: italic;
    line-height: 1.5;
    color: var(--color-text-secondary);
}

.closing-cta {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--color-text);
    text-decoration: none;
    padding-bottom: 0.25rem;
    border-bottom: 1px solid var(--color-text);
    transition: all var(--duration-fast) ease;
}

.closing-cta:hover {
    color: var(--color-accent);
    border-color: var(--color-accent);
}

/* ========================================
   Site Footer
   ======================================== */

.site-footer {
    padding: var(--space-lg);
    border-top: 1px solid var(--color-border);
}

.footer-inner {
    max-width: var(--max-width-wide);
    margin: 0 auto;
    text-align: center;
}

.site-footer span {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
}

/* ========================================
   Reading Page
   ======================================== */

.reading-page {
    min-height: 100vh;
}

/* Progress bar */
.reading-progress {
    position: fixed;
    top: 0;
    left: 0;
    width: 0%;
    height: 2px;
    background-color: var(--color-accent);
    z-index: 200;
    transition: width 0.1s linear;
}

/* Reading header */
.reading-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background-color: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    transform: translateY(0);
    transition: transform var(--duration-medium) var(--ease-out-expo);
}

.reading-header.hidden {
    transform: translateY(-100%);
}

.reading-header-inner {
    max-width: var(--max-width-wide);
    margin: 0 auto;
    padding: var(--space-sm) var(--space-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.reading-header-title {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--color-text);
    text-decoration: none;
}

.reading-header-chapter {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    color: var(--color-text-tertiary);
}

.reading-header-nav {
    display: flex;
    gap: var(--space-sm);
}

.reading-header-nav button {
    background: none;
    border: 1px solid var(--color-border);
    padding: 0.4rem 0.8rem;
    font-family: var(--font-ui);
    font-size: 0.7rem;
    color: var(--color-text-secondary);
    cursor: pointer;
    transition: all var(--duration-fast) ease;
}

.reading-header-nav button:hover:not(:disabled) {
    border-color: var(--color-text);
    color: var(--color-text);
}

.reading-header-nav button:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

/* Chapter display */
.chapter {
    max-width: var(--max-width-content);
    margin: 0 auto;
    padding: var(--space-2xl) var(--space-lg);
}

.chapter-meta {
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 1px solid var(--color-border);
}

.chapter-part {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-xs);
}

.chapter-number {
    font-family: var(--font-ui);
    font-size: 0.8rem;
    color: var(--color-text-secondary);
    margin-bottom: var(--space-sm);
}

.chapter-title {
    font-family: var(--font-display);
    font-size: clamp(2rem, 5vw, 3rem);
    font-weight: 400;
    line-height: 1.15;
    letter-spacing: -0.02em;
    margin-bottom: var(--space-md);
}

.chapter-reading-time {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    color: var(--color-text-tertiary);
}

/* Chapter content */
.chapter-content {
    font-size: 1.125rem;
    line-height: 1.85;
}

.chapter-content p {
    margin-bottom: 1.5em;
}

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

/* Chapter ornament */
.chapter-ornament {
    text-align: center;
    margin-bottom: var(--space-md);
    color: var(--color-border-dark);
    font-size: 1.25rem;
    letter-spacing: 0.5em;
    opacity: 0.4;
}

.chapter-ornament::before {
    content: "···";
}

/* Chapter navigation */
.chapter-footer {
    margin-top: var(--space-2xl);
    padding-top: var(--space-xl);
    border-top: 1px solid var(--color-border);
}

.chapter-nav-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-md);
}

.chapter-nav-link {
    display: flex;
    flex-direction: column;
    justify-content: center;
    text-decoration: none;
    padding: var(--space-lg) var(--space-md);
    background-color: var(--color-bg-warm);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    min-height: 120px;
    transition: all var(--duration-medium) var(--ease-out-expo);
}

.chapter-nav-link:hover {
    border-color: var(--color-accent);
    background-color: var(--color-bg-alt);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
}

.chapter-nav-link.prev {
    text-align: left;
}

.chapter-nav-link.next {
    text-align: right;
}

.chapter-nav-label {
    display: block;
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    margin-bottom: var(--space-sm);
}

.chapter-nav-title {
    font-family: var(--font-display);
    font-size: 1.35rem;
    color: var(--color-text);
    line-height: 1.3;
}

.chapter-nav-placeholder {
    /* Empty grid cell */
}

/* Table of contents drawer */
.toc-drawer {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 460px;
    max-width: 90vw;
    background-color: var(--color-bg);
    border-right: 1px solid var(--color-border);
    z-index: 300;
    transform: translateX(-100%);
    transition: transform var(--duration-medium) var(--ease-out-expo);
    overflow-y: auto;
}

.toc-drawer.open {
    transform: translateX(0);
}

.toc-drawer-overlay {
    position: fixed;
    inset: 0;
    background-color: rgba(0, 0, 0, 0.3);
    z-index: 299;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--duration-medium) ease, visibility var(--duration-medium) ease;
}

.toc-drawer-overlay.visible {
    opacity: 1;
    visibility: visible;
}

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

.toc-drawer-title {
    font-family: var(--font-display);
    font-size: 1.25rem;
}

.toc-drawer-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--color-text-secondary);
    cursor: pointer;
    padding: 0.5rem;
    line-height: 1;
}

.toc-drawer-content {
    padding: var(--space-lg);
}

.toc-drawer-part {
    margin-bottom: var(--space-lg);
}

.toc-drawer-part-title {
    font-family: var(--font-ui);
    font-size: 0.65rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-tertiary);
    margin-bottom: var(--space-sm);
}

.toc-drawer-chapters {
    list-style: none;
}

.toc-drawer-chapters a {
    display: block;
    padding: 0.6rem 0;
    font-family: var(--font-body);
    font-size: 1rem;
    color: var(--color-text-secondary);
    text-decoration: none;
    border-bottom: 1px solid var(--color-border);
    transition: color var(--duration-fast) ease;
}

.toc-drawer-chapters a:hover,
.toc-drawer-chapters a.active {
    color: var(--color-text);
}

.toc-drawer-chapters a.active {
    font-weight: 500;
}

/* Toggle button */
.toc-toggle {
    position: fixed;
    bottom: var(--space-lg);
    left: var(--space-lg);
    z-index: 100;
    background-color: var(--color-bg);
    border: 1px solid var(--color-border);
    padding: var(--space-sm) var(--space-md);
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text);
    cursor: pointer;
    transition: all var(--duration-fast) ease;
}

.toc-toggle:hover {
    border-color: var(--color-text);
}

/* ========================================
   Responsive
   ======================================== */

@media (max-width: 1024px) {
    .toc-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 768px) {
    :root {
        --space-lg: 2rem;
        --space-xl: 3rem;
        --space-2xl: 4rem;
    }
    
    .site-header {
        padding: var(--space-sm) var(--space-md);
    }
    
    .hero {
        padding: var(--space-lg) var(--space-md);
        min-height: 70vh;
    }
    
    .premise-inner {
        grid-template-columns: 1fr;
        gap: var(--space-sm);
    }
    
    .premise-number {
        font-size: 0.65rem;
    }
    
    .toc-grid {
        grid-template-columns: 1fr;
    }
    
    .chapter-nav-grid {
        grid-template-columns: 1fr;
    }
    
    .chapter-nav-link.next {
        text-align: left;
    }
    
    .reading-header-inner {
        padding: var(--space-sm) var(--space-md);
    }
    
    .reading-header-chapter {
        display: none;
    }
    
    .chapter {
        padding: var(--space-lg) var(--space-md);
    }
    
    /* Hide floating buttons on mobile - use header instead */
    .toc-toggle {
        display: none;
    }
    
    .reading-page .theme-toggle {
        display: none;
    }
    
    .continue-reading {
        left: var(--space-md);
        right: var(--space-md);
        bottom: var(--space-md);
        transform: translateX(0) translateY(100px);
        flex-direction: column;
        text-align: center;
        gap: var(--space-sm);
    }
    
    .continue-reading.visible {
        transform: translateX(0) translateY(0);
    }
    
    .toc-drawer {
        width: 100%;
        max-width: 100%;
    }
    
    /* Add theme toggle to header on mobile */
    .reading-header-nav {
        display: flex;
        align-items: center;
        gap: 0.5rem;
    }
    
    .reading-header-nav .mobile-theme-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
        background: none;
        border: 1px solid var(--color-border);
        padding: 0.4rem;
        cursor: pointer;
        color: var(--color-text-secondary);
    }
    
    .reading-header-nav .mobile-theme-toggle svg {
        width: 14px;
        height: 14px;
    }
}

@media (max-width: 480px) {
    html {
        font-size: 16px;
    }
    
    .hero-title {
        font-size: 3rem;
    }
    
    .toc-header {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--space-xs);
    }
}

/* ========================================
   Theme Toggle
   ======================================== */

.theme-toggle {
    position: fixed;
    bottom: var(--space-lg);
    right: var(--space-lg);
    z-index: 100;
    background-color: var(--color-bg-warm);
    border: 1px solid var(--color-border);
    border-radius: 50%;
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--duration-fast) ease;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

.theme-toggle:hover {
    border-color: var(--color-accent);
    transform: scale(1.05);
}

.theme-toggle svg {
    width: 20px;
    height: 20px;
    color: var(--color-text);
}

.theme-toggle .icon-sun {
    display: none;
}

.theme-toggle .icon-moon {
    display: block;
}

[data-theme="dark"] .theme-toggle .icon-sun {
    display: block;
}

[data-theme="dark"] .theme-toggle .icon-moon {
    display: none;
}

@media (prefers-color-scheme: dark) {
    .theme-toggle .icon-sun {
        display: block;
    }
    
    .theme-toggle .icon-moon {
        display: none;
    }
}

/* Dark mode adjustments */
@media (prefers-color-scheme: dark) {
    .chapter-nav-link:hover {
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    }
    
    .site-header {
        mix-blend-mode: normal;
    }
    
    .header-label,
    .header-download {
        color: var(--color-text-secondary);
    }
}

[data-theme="dark"] .chapter-nav-link:hover {
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .site-header {
    mix-blend-mode: normal;
}

[data-theme="dark"] .header-label,
[data-theme="dark"] .header-download {
    color: var(--color-text-secondary);
}

/* ========================================
   Continue Reading Banner
   ======================================== */

.continue-reading {
    position: fixed;
    bottom: var(--space-lg);
    left: 50%;
    transform: translateX(-50%) translateY(100px);
    z-index: 100;
    background-color: var(--color-bg-warm);
    border: 1px solid var(--color-border);
    border-radius: 4px;
    padding: var(--space-sm) var(--space-md);
    display: flex;
    align-items: center;
    gap: var(--space-md);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    opacity: 0;
    transition: transform var(--duration-medium) var(--ease-out-expo),
                opacity var(--duration-medium) ease;
}

.continue-reading.visible {
    transform: translateX(-50%) translateY(0);
    opacity: 1;
}

.continue-reading-text {
    font-family: var(--font-ui);
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

.continue-reading-text strong {
    color: var(--color-text);
    font-weight: 500;
}

.continue-reading-btn {
    font-family: var(--font-ui);
    font-size: 0.75rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--color-bg);
    background-color: var(--color-accent);
    border: none;
    padding: 0.5rem 1rem;
    border-radius: 2px;
    cursor: pointer;
    text-decoration: none;
    transition: background-color var(--duration-fast) ease;
}

.continue-reading-btn:hover {
    background-color: var(--color-accent-light);
}

.continue-reading-dismiss {
    background: none;
    border: none;
    color: var(--color-text-tertiary);
    cursor: pointer;
    padding: 0.25rem;
    font-size: 1.25rem;
    line-height: 1;
}

.continue-reading-dismiss:hover {
    color: var(--color-text);
}

/* ========================================
   References Page
   ======================================== */

.references-section {
    padding: var(--space-xl) var(--space-lg);
    border-top: 1px solid var(--color-border);
}

.references-inner {
    max-width: var(--max-width-wide);
    margin: 0 auto;
}

.references-title {
    font-family: var(--font-display);
    font-size: 2rem;
    margin-bottom: var(--space-lg);
}

.references-intro {
    font-family: var(--font-body);
    font-size: 1.125rem;
    line-height: 1.75;
    color: var(--color-text-secondary);
    margin-bottom: var(--space-xl);
}

.reference-category {
    margin-bottom: var(--space-xl);
}

.reference-category-title {
    font-family: var(--font-ui);
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--color-accent);
    margin-bottom: var(--space-md);
    padding-bottom: var(--space-xs);
    border-bottom: 1px solid var(--color-border);
}

.reference-list {
    list-style: none;
}

.reference-item {
    padding: var(--space-sm) 0;
    border-bottom: 1px solid var(--color-border);
}

.reference-item:last-child {
    border-bottom: none;
}

.reference-authors {
    font-family: var(--font-body);
    font-size: 1rem;
    color: var(--color-text);
    margin-bottom: 0.25rem;
}

.reference-title {
    font-family: var(--font-body);
    font-size: 1rem;
    font-style: italic;
    color: var(--color-text-secondary);
    margin-bottom: 0.25rem;
}

.reference-source {
    font-family: var(--font-ui);
    font-size: 0.8rem;
    color: var(--color-text-tertiary);
}

/* Chapter progress bar */
.chapter-progress {
    position: fixed;
    bottom: 0;
    left: 0;
    width: 0%;
    height: 3px;
    background-color: var(--color-accent);
    opacity: 0.6;
    z-index: 50;
    transition: width 0.1s linear;
}

/* Smooth chapter transitions */
.chapter-content.transitioning {
    opacity: 0;
    transform: translateY(20px);
}

.chapter-content {
    transition: opacity 0.4s ease, transform 0.4s ease;
}

/* Read indicator in TOC */
.toc-drawer-chapters a.read::after {
    content: "✓";
    margin-left: 0.5rem;
    color: var(--color-accent);
    font-size: 0.75rem;
}

/* Dark mode adjustments for new elements */
@media (prefers-color-scheme: dark) {
    .continue-reading {
        box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
    }
}

[data-theme="dark"] .continue-reading {
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
}

/* Mobile theme toggle in header */
.mobile-theme-toggle {
    display: none;
}

.mobile-theme-toggle .icon-sun {
    display: none;
}

.mobile-theme-toggle .icon-moon {
    display: block;
}

[data-theme="dark"] .mobile-theme-toggle .icon-sun {
    display: block;
}

[data-theme="dark"] .mobile-theme-toggle .icon-moon {
    display: none;
}

@media (prefers-color-scheme: dark) {
    .mobile-theme-toggle .icon-sun {
        display: block;
    }
    
    .mobile-theme-toggle .icon-moon {
        display: none;
    }
}

@media (max-width: 768px) {
    .mobile-theme-toggle {
        display: flex;
    }
}

/* ========================================
   Accessibility - Focus Styles
   ======================================== */

/* Visible focus outline for all interactive elements */
a:focus-visible,
button:focus-visible,
[tabindex]:focus-visible {
    outline: 2px solid var(--color-accent);
    outline-offset: 2px;
}

/* Remove default outline since we're using focus-visible */
a:focus:not(:focus-visible),
button:focus:not(:focus-visible),
[tabindex]:focus:not(:focus-visible) {
    outline: none;
}

/* High contrast focus for dark mode */
@media (prefers-color-scheme: dark) {
    a:focus-visible,
    button:focus-visible,
    [tabindex]:focus-visible {
        outline-color: var(--color-accent-light);
    }
}

[data-theme="dark"] a:focus-visible,
[data-theme="dark"] button:focus-visible,
[data-theme="dark"] [tabindex]:focus-visible {
    outline-color: var(--color-accent-light);
}

/* ========================================
   About Section (Landing Page)
   ======================================== */

.about-section {
    padding: var(--space-xl) var(--space-lg);
    border-top: 1px solid var(--color-border);
}

.about-inner {
    max-width: var(--max-width-content);
    margin: 0 auto;
}

.about-title {
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 400;
    margin-bottom: var(--space-lg);
    color: var(--color-text);
}

.about-content {
    font-family: var(--font-body);
    font-size: 1.0625rem;
    line-height: 1.8;
    color: var(--color-text-secondary);
}

.about-content p {
    margin-bottom: 1.25em;
}

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

.about-content strong {
    color: var(--color-text);
    font-weight: 500;
}