/* MarkOwl iiSU Edition - Style Moderne et Audacieux */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Bebas+Neue&family=Space+Grotesk:wght@300;400;500;600;700&display=swap');

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

:root {
    /* iiSU Color Palette - Améliorée pour lisibilité */
    --iisu-black: #000000;
    --iisu-dark: #1A1A1A;
    --iisu-gray: #2A2A2A;
    --iisu-medium: #404040;
    --iisu-light: #F0F0F0;
    --iisu-white: #FFFFFF;
    
    /* iiSU Accent Colors - Plus visibles */
    --iisu-red: #007CE5;
    --iisu-orange: #0056B3;
    --iisu-purple: #8E24AA;
    --iisu-cyan: #00ACC1;
    --iisu-yellow: #0088CC;
    
    /* Semantic Colors */
    --primary: var(--iisu-black);
    --secondary: var(--iisu-white);
    --accent: var(--iisu-red);
    --accent-alt: #0056B3;
    
    /* Text Colors - Améliorés */
    --text-primary: #FFFFFF;
    --text-secondary: #B0B0B0;
    --text-muted: #808080;
    --text-accent: var(--iisu-red);
    
    /* Background Colors */
    --bg-primary: #313131;
    --bg-secondary: #313131;
    --bg-card: rgba(255, 255, 255, 0.05);
    --bg-card-hover: rgba(229, 57, 53, 0.1);
    
    /* Typography */
    --font-display: 'Bebas Neue', cursive;
    --font-heading: 'Space Grotesk', sans-serif;
    --font-body: 'Inter', sans-serif;
    
    /* Font Sizes - Améliorés pour lisibilité */
    --text-xs: 0.75rem;
    --text-sm: 0.875rem;
    --text-base: 1rem;
    --text-lg: 1.125rem;
    --text-xl: 1.25rem;
    --text-2xl: 1.5rem;
    --text-3xl: 1.875rem;
    --text-4xl: 2.25rem;
    --text-5xl: 3rem;
    --text-6xl: 3.75rem;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.2);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.4);
    --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.5);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-base: 0.3s ease;
    --transition-slow: 0.5s ease;
    
    /* Spacing */
    --space-xs: 0.25rem;
    --space-sm: 0.5rem;
    --space-md: 1rem;
    --space-lg: 1.5rem;
    --space-xl: 2rem;
    --space-2xl: 3rem;
    --space-3xl: 4rem;
}

/* Light mode override - iiSU Edition */
[data-theme="light"] {
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8F9FA;
    --bg-card: rgba(0, 0, 0, 0.03);
    --bg-card-hover: rgba(229, 57, 53, 0.08);
    
    --text-primary: #1A1A1A;
    --text-secondary: #4A4A4A;
    --text-muted: #6A6A6A;
    --text-accent: var(--iisu-red);
    
    --iisu-black: #FFFFFF;
    --iisu-dark: #F8F9FA;
    --iisu-gray: #E9ECEF;
    --iisu-medium: #DEE2E6;
    --iisu-light: #1A1A1A;
    --iisu-white: #000000;
    
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 16px 48px rgba(0, 0, 0, 0.15);
}

/* Dark mode override - iiSU Edition */
[data-theme="dark"] {
    --bg-primary: #1a1a1a;
    --bg-secondary: #242424;
    --bg-card: rgba(255, 255, 255, 0.08);
    --bg-card-hover: rgba(0, 124, 229, 0.15);
    
    --text-primary: #f5f5f5;
    --text-secondary: #b8b8b8;
    --text-muted: #888888;
    --text-accent: var(--iisu-red);
    
    --iisu-black: #0d0d0d;
    --iisu-dark: #1a1a1a;
    --iisu-gray: #2d2d2d;
    --iisu-medium: #404040;
    --iisu-light: #e0e0e0;
    --iisu-white: #ffffff;
    
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-xl: 0 16px 64px rgba(0, 0, 0, 0.6);
}

body {
    font-family: var(--font-body);
    font-size: var(--text-base);
    font-weight: 400;
    line-height: 1.7;
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Smooth scrolling */
html {
    scroll-behavior: smooth;
}

/* Custom scrollbar */
::-webkit-scrollbar {
    width: 8px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--iisu-red);
    border-radius: 4px;
}

/* Header Minimaliste iiSU */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    transition: all var(--transition-base);
}

/* Light mode header */
[data-theme="light"] .header {
    background: rgba(255, 255, 255, 0.95);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
}

/* Dark mode header */
[data-theme="dark"] .header {
    background: rgba(26, 26, 26, 0.95);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.header.scrolled {
    background: rgba(26, 26, 26, 0.98);
    backdrop-filter: blur(30px);
}

[data-theme="dark"] .header.scrolled {
    background: rgba(26, 26, 26, 0.98);
}

[data-theme="light"] .header.scrolled {
    background: rgba(255, 255, 255, 0.98);
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1.5rem 0.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo-section {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-icon {
    width: 104px;
    height: 104px;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-base);
}

.logo-img {
    width: 100%;
    height: 100%;
    object-fit: contain;
}


@keyframes shimmer {
    0% { transform: translateX(-100%) translateY(-100%) rotate(45deg); }
    100% { transform: translateX(100%) translateY(100%) rotate(45deg); }
}

.brand-info {
    display: flex;
    flex-direction: column;
}

.brand-name {
    font-family: var(--font-display);
    font-size: var(--text-2xl);
    font-weight: 900;
    color: var(--text-primary);
    line-height: 1;
    letter-spacing: -0.02em;
}

.slogan {
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-secondary);
    letter-spacing: 0.05em;
    text-transform: uppercase;
    margin-top: var(--space-xs);
}

.nav-section {
    display: flex;
    align-items: center;
    gap: 2rem;
}

.theme-toggle {
    width: 45px;
    height: 45px;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all var(--transition-base);
    font-family: var(--font-display);
    font-size: 14px;
    font-weight: 900;
    color: var(--text-primary);
}

/* Light mode theme toggle */
[data-theme="light"] .theme-toggle {
    background: rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.theme-toggle:hover {
    background: var(--iisu-red);
    transform: scale(1.05);
    border-color: var(--iisu-red);
    color: var(--iisu-white);
}

.system-info {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.time-display {
    font-family: var(--font-display);
    font-size: 1.125rem;
    font-weight: 700;
    color: var(--text-primary);
    padding: 0.5rem 1rem;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    border: 1px solid rgba(255, 255, 255, 0.2);
}

/* Light mode time display */
[data-theme="light"] .time-display {
    background: rgba(0, 0, 0, 0.05);
    border: 1px solid rgba(0, 0, 0, 0.1);
}

.battery-indicator {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 0.75rem;
    background: rgba(0, 255, 64, 0.1);
    border: 1px solid rgba(0, 255, 64, 0.3);
    border-radius: 8px;
}

/* Light mode battery indicator */
[data-theme="light"] .battery-indicator {
    background: rgba(0, 200, 83, 0.1);
    border: 1px solid rgba(0, 200, 83, 0.3);
}

.battery-icon {
    width: 24px;
    height: 12px;
    background: #00FF40;
    border-radius: 2px;
    position: relative;
}

[data-theme="light"] .battery-icon {
    background: #00C853;
}

.battery-icon::after {
    content: '';
    position: absolute;
    right: -3px;
    top: 2px;
    width: 2px;
    height: 8px;
    background: #00FF40;
    border-radius: 0 1px 1px 0;
}

[data-theme="light"] .battery-icon::after {
    background: #00C853;
}

.battery-text {
    font-family: var(--font-heading);
    font-size: 0.75rem;
    font-weight: 600;
    color: #00FF40;
}

[data-theme="light"] .battery-text {
    color: #00C853;
}

/* Hero Section Plein Écran */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 50%, #242424 100%);
    overflow: hidden;
}

/* Light mode hero */
[data-theme="light"] .hero {
    background: linear-gradient(135deg, #F8F9FA 0%, #E9ECEF 100%);
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(0, 0, 0, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(0, 0, 0, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(0, 0, 0, 0.05) 0%, transparent 50%);
    pointer-events: none;
}

/* Light mode hero overlay */
[data-theme="light"] .hero::before {
    background: 
        radial-gradient(circle at 20% 80%, rgba(229, 57, 53, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(142, 36, 170, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(251, 140, 0, 0.03) 0%, transparent 50%);
}

/* Dark mode hero overlay */
[data-theme="dark"] .hero::before {
    background: 
        radial-gradient(circle at 20% 80%, rgba(0, 124, 229, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(142, 36, 170, 0.06) 0%, transparent 50%),
        radial-gradient(circle at 50% 50%, rgba(0, 124, 229, 0.04) 0%, transparent 50%);
}

.hero-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    text-align: center;
    position: relative;
    z-index: 1;
}

.hero-logo {
    max-width: 100%;
    height: auto;
    width: clamp(527px, 87.75vw, 1404px);
    margin-top: 15vh;
    animation: titleReveal 1s ease forwards;
    opacity: 0;
    transition: all 0.3s ease;
    cursor: pointer;
}

.hero-logo-link {
    display: inline-block;
    text-decoration: none;
    cursor: pointer;
}

.hero-logo:hover {
    transform: perspective(800px) rotateY(20deg) rotateX(-10deg) rotateZ(3deg) scale(1.08);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.hero-description {
    max-width: 800px;
    margin: 3rem auto 2rem;
    text-align: center;
}

.hero-description p {
    font-family: var(--font-body);
    font-size: var(--text-lg);
    line-height: 1.8;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    opacity: 0;
    animation: fadeInUp 1s ease 0.5s forwards;
}

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

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-actions {
    margin-top: 3rem;
    text-align: center;
}

.hero-button {
    display: inline-block;
    padding: 1rem 2.5rem;
    background: linear-gradient(135deg, var(--iisu-red) 0%, #0056B3 100%);
    color: var(--iisu-white);
    text-decoration: none;
    border-radius: 50px;
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    transition: all var(--transition-base);
    border: 2px solid transparent;
    box-shadow: 0 8px 24px rgba(0, 124, 229, 0.3);
    cursor: pointer;
}

.hero-button:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 12px 32px rgba(0, 124, 229, 0.4);
    border-color: rgba(255, 255, 255, 0.2);
    background: linear-gradient(135deg, #0056B3 0%, var(--iisu-red) 100%);
}

.hero-title {
    font-family: var(--font-display);
    font-size: clamp(1.5rem, 5vw, 4rem);
    font-weight: 900;
    line-height: 0.95;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-xl);
    color: var(--text-primary);
    animation: titleReveal 1s ease forwards;
    opacity: 0;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.hero-title a {
    text-decoration: none;
    display: inline-block;
}

.hero-title img {
    width: 100%;
    height: auto;
    max-width: 100%;
    margin-top: 200px;
    animation: titleReveal 1s ease forwards;
    opacity: 0;
    transition: transform 0.3s ease;
}

.hero-title img:hover {
    transform: scale(1.05);
}

/* Light mode hero title */
[data-theme="light"] .hero-title {
    color: var(--text-primary);
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

@keyframes titleReveal {
    from {
        opacity: 0;
        transform: translateY(50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.hero-subtitle {
    font-family: var(--font-heading);
    font-size: clamp(1.125rem, 2.5vw, 1.5rem);
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: var(--space-2xl);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
    animation: subtitleReveal 1s ease 0.3s forwards;
    opacity: 0;
    line-height: 1.6;
}

@keyframes subtitleReveal {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Navigation Grid iiSU */
.nav-grid {
    max-width: 1400px;
    margin: 0 auto;
    padding: 4rem 2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.nav-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 16px;
    padding: var(--space-2xl) var(--space-xl);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(10px);
}

/* Light mode nav cards */
[data-theme="light"] .nav-card {
    background: rgba(255, 255, 255, 0.8);
    border: 1px solid rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(20px);
}

.nav-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.nav-card:hover {
    transform: translateY(-10px) scale(1.02);
    border-color: var(--iisu-red);
    background: rgba(0, 124, 229, 0.1);
    box-shadow: 0 20px 40px rgba(0, 124, 229, 0.2);
}

.nav-card:hover::before {
    opacity: 1;
}

.nav-icon {
    width: 100px;
    height: 100px;
    margin: 0 auto 2rem;
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-display);
    font-size: 3rem;
    font-weight: 900;
    color: var(--iisu-white);
    position: relative;
    overflow: hidden;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
    transition: all var(--transition-base);
}

.nav-icon::after {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transform: rotate(45deg);
    transition: all 0.6s ease;
}

.nav-card:hover .nav-icon::after {
    animation: iconShimmer 0.6s ease;
}

@keyframes iconShimmer {
    0% { transform: translateX(-100%) translateY(-100%) rotate(45deg); }
    100% { transform: translateX(100%) translateY(100%) rotate(45deg); }
}

/* Icon Colors */
.icon-home { background: linear-gradient(135deg, var(--iisu-red) 0%, #0056B3 100%); }
.icon-lessons { background: linear-gradient(135deg, var(--iisu-purple) 0%, #BA55D3 100%); }
.icon-editor { background: linear-gradient(135deg, var(--iisu-cyan) 0%, #00CED1 100%); }
.icon-examples { background: linear-gradient(135deg, #0088CC 0%, #0066AA 100%); }
.icon-settings { background: linear-gradient(135deg, #0056B3 0%, #004494 100%); }
.icon-help { background: linear-gradient(135deg, var(--iisu-red) 0%, #FF1493 100%); }

.nav-title {
    font-family: var(--font-heading);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
    line-height: 1.3;
}

.nav-description {
    font-family: var(--font-body);
    font-size: var(--text-base);
    color: var(--text-secondary);
    opacity: 0.9;
    line-height: 1.5;
}

/* Content Sections */
.content-section {
    display: none;
    min-height: 100vh;
    padding: 8rem 2rem 4rem;
    animation: sectionReveal 0.6s ease;
}

.content-section.active {
    display: block;
}

@keyframes sectionReveal {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section-container {
    max-width: 1400px;
    margin: 0 auto;
}

.section-header {
    margin-bottom: 4rem;
    text-align: center;
}

.section-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 2rem;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 900;
    color: var(--iisu-white);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.section-title {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 900;
    line-height: 0.95;
    letter-spacing: -0.03em;
    margin-bottom: var(--space-md);
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--iisu-red) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.section-subtitle {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 500;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.6;
}

/* Welcome Card */
.welcome-card {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 24px;
    padding: 4rem 3rem;
    text-align: center;
    margin-bottom: 4rem;
    position: relative;
    overflow: hidden;
}

/* Light mode welcome card */
[data-theme="light"] .welcome-card {
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid rgba(0, 0, 0, 0.1);
    box-shadow: var(--shadow-lg);
}

.welcome-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 0, 64, 0.1) 0%, rgba(139, 0, 255, 0.1) 100%);
    pointer-events: none;
}

/* Light mode welcome card overlay */
[data-theme="light"] .welcome-card::before {
    background: linear-gradient(135deg, rgba(229, 57, 53, 0.05) 0%, rgba(142, 36, 170, 0.05) 100%);
}

.welcome-title {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 900;
    line-height: 0.9;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--iisu-white) 0%, var(--iisu-red) 50%, #0056B3 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-subtitle {
    font-family: var(--font-heading);
    font-size: 1.25rem;
    color: var(--iisu-light);
    margin-bottom: 2rem;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 4rem;
}

.feature-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 20px;
    padding: 3rem 2rem;
    text-align: center;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

/* Light mode feature cards */
[data-theme="light"] .feature-card {
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid rgba(0, 0, 0, 0.1);
    box-shadow: var(--shadow-md);
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.feature-card:hover {
    transform: translateY(-10px);
    border-color: var(--iisu-red);
    background: rgba(0, 124, 229, 0.1);
    box-shadow: 0 20px 40px rgba(0, 124, 229, 0.2);
}

.feature-card:hover::before {
    opacity: 1;
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 2rem;
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-display);
    font-size: 2rem;
    font-weight: 900;
    color: var(--iisu-white);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.feature-title {
    font-family: var(--font-heading);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
    line-height: 1.3;
}

.feature-description {
    font-family: var(--font-body);
    font-size: var(--text-base);
    color: var(--text-secondary);
    opacity: 0.9;
    line-height: 1.6;
}

/* Lessons Grid */
.lessons-grid {
    display: grid;
    gap: 1.5rem;
}

.lesson-card {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    padding: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

/* Light mode lesson cards */
[data-theme="light"] .lesson-card {
    background: rgba(255, 255, 255, 0.9);
    border: 1px solid rgba(0, 0, 0, 0.1);
    box-shadow: var(--shadow-sm);
}

.lesson-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.1) 0%, transparent 50%);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.lesson-card:hover {
    transform: translateX(20px);
    border-color: var(--iisu-red);
    background: rgba(0, 124, 229, 0.1);
    box-shadow: 0 10px 30px rgba(0, 124, 229, 0.2);
}

.lesson-card:hover::before {
    opacity: 1;
}

.lesson-info {
    flex: 1;
}

.lesson-title {
    font-family: var(--font-heading);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-sm);
    line-height: 1.3;
}

.lesson-meta {
    font-family: var(--font-body);
    font-size: var(--text-sm);
    color: var(--text-secondary);
    opacity: 0.9;
}

.lesson-level {
    padding: 0.75rem 1.5rem;
    border-radius: 50px;
    font-family: var(--font-heading);
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.level-beginner {
    background: rgba(0, 255, 64, 0.2);
    color: #00FF40;
    border: 1px solid rgba(0, 255, 64, 0.3);
}

.level-intermediate {
    background: rgba(0, 136, 204, 0.2);
    color: #0088CC;
    border: 1px solid rgba(0, 136, 204, 0.3);
}

.level-advanced {
    background: rgba(0, 124, 229, 0.2);
    color: var(--iisu-red);
    border: 1px solid rgba(0, 124, 229, 0.3);
}

/* Editor Section */
.editor-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    height: 600px;
}

.editor-panel {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 16px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
}

.panel-header {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 1px solid rgba(255, 255, 255, 0.15);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

#markdown-input, #html-output {
    flex: 1;
    background: rgba(0, 0, 0, 0.4);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 12px;
    padding: var(--space-lg);
    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
    font-size: var(--text-sm);
    color: var(--text-primary);
    resize: none;
    outline: none;
    line-height: 1.6;
}

/* Light mode editor */
[data-theme="light"] #markdown-input, 
[data-theme="light"] #html-output {
    background: rgba(0, 0, 0, 0.02);
    border: 1px solid rgba(0, 0, 0, 0.1);
    color: #1A1A1A;
}

#markdown-input:focus, #html-output:focus {
    border-color: var(--iisu-red);
    box-shadow: 0 0 20px rgba(0, 124, 229, 0.2);
}

#html-output {
    overflow-y: auto;
    font-family: var(--font-body);
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(10, 10, 10, 0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding: 1.5rem 0;
    z-index: 1000;
}

/* Light mode bottom nav */
[data-theme="light"] .bottom-nav {
    background: rgba(255, 255, 255, 0.95);
    border-top: 1px solid rgba(0, 0, 0, 0.1);
}

/* Dark mode bottom nav */
[data-theme="dark"] .bottom-nav {
    background: rgba(26, 26, 26, 0.95);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.nav-button {
    background: var(--bg-card);
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 12px;
    padding: var(--space-md) var(--space-xl);
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-base);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    backdrop-filter: blur(10px);
}

.nav-button:hover {
    background: var(--iisu-red);
    color: var(--iisu-white);
    transform: translateY(-2px);
    border-color: var(--iisu-red);
    box-shadow: 0 10px 20px rgba(0, 124, 229, 0.3);
}

.nav-button.active {
    background: var(--iisu-red);
    color: var(--iisu-white);
    border-color: var(--iisu-red);
    box-shadow: 0 10px 20px rgba(0, 124, 229, 0.3);
}

/* Footer Navigation */
.footer-nav {
    background: rgba(26, 26, 26, 0.95);
    backdrop-filter: blur(20px);
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding: 1.5rem 0;
    margin-top: 4rem;
}

.footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
}

.footer-section {
    text-align: center;
}

.footer-title {
    font-family: var(--font-heading);
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.footer-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-family: var(--font-body);
    font-size: var(--text-base);
    transition: all var(--transition-base);
    padding: 0.5rem 1rem;
    border-radius: 8px;
}

.footer-link:hover {
    color: var(--iisu-red);
    background: rgba(0, 124, 229, 0.1);
    transform: translateY(-2px);
}

.footer-icon {
    font-size: var(--text-lg);
}

.social-links {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.social-link {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--text-secondary);
    text-decoration: none;
    font-family: var(--font-body);
    font-size: var(--text-base);
    transition: all var(--transition-base);
    padding: 0.75rem 1rem;
    border-radius: 8px;
    background: rgba(255, 255, 255, 0.05);
}

.social-link:hover {
    color: var(--text-primary);
    background: rgba(0, 124, 229, 0.15);
    transform: translateX(5px);
}

.social-icon {
    font-size: var(--text-lg);
}

.resource-links {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.resource-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-family: var(--font-body);
    font-size: var(--text-base);
    transition: all var(--transition-base);
    padding: 0.5rem 0;
    border-bottom: 1px solid transparent;
}

.resource-link:hover {
    color: var(--iisu-red);
    border-bottom-color: var(--iisu-red);
    transform: translateX(3px);
}

.footer-bottom {
    text-align: center;
    padding: 1.5rem 0;
    margin: 0;
}

.footer-bottom p {
    color: var(--text-muted);
    font-family: var(--font-body);
    font-size: var(--text-sm);
    margin: 0;
}

/* Light mode footer */
[data-theme="light"] .footer-nav {
    background: rgba(255, 255, 255, 0.95);
    border-top-color: rgba(0, 0, 0, 0.1);
}

/* Documentation Page Styles */
.doc-sidebar {
    position: fixed;
    left: 0;
    top: 80px;
    width: 280px;
    height: calc(100vh - 80px);
    background: var(--bg-secondary);
    border-right: 1px solid rgba(255, 255, 255, 0.1);
    overflow-y: auto;
    z-index: 100;
    transition: transform 0.3s ease;
}

.doc-sidebar.collapsed {
    transform: translateX(-100%);
}

.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.sidebar-title {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.sidebar-toggle {
    background: var(--iisu-red);
    color: var(--iisu-white);
    border: none;
    padding: 0.5rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: var(--text-base);
}

.sidebar-content {
    padding: 0.5rem;
}

.nav-list {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.nav-link {
    display: block;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-family: var(--font-body);
    font-size: var(--text-sm);
    transition: all var(--transition-base);
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--iisu-red);
    background: rgba(0, 124, 229, 0.1);
    transform: translateX(3px);
}

.nav-text {
    display: block;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.doc-main {
    margin-left: 280px;
    min-height: 100vh;
    background: var(--bg-primary);
}

.doc-hero {
    padding: 4rem 2rem;
    text-align: center;
    background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.doc-title {
    font-family: var(--font-display);
    font-size: clamp(2.5rem, 5vw, 4rem);
    font-weight: 900;
    color: var(--text-primary);
    margin-bottom: 1rem;
    animation: fadeInUp 1s ease forwards;
}

.doc-subtitle {
    font-family: var(--font-body);
    font-size: var(--text-lg);
    color: var(--text-secondary);
    margin-bottom: 3rem;
    animation: fadeInUp 1s ease 0.2s forwards;
    opacity: 0;
}

.doc-stats {
    display: flex;
    justify-content: center;
    gap: 3rem;
    animation: fadeInUp 1s ease 0.4s forwards;
    opacity: 0;
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-family: var(--font-display);
    font-size: var(--text-3xl);
    font-weight: 900;
    color: var(--iisu-red);
}

.stat-label {
    font-family: var(--font-body);
    font-size: var(--text-sm);
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.editor-section {
    padding: 3rem 2rem;
    background: var(--bg-primary);
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-title {
    font-family: var(--font-heading);
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

.section-subtitle {
    font-family: var(--font-body);
    font-size: var(--text-base);
    color: var(--text-secondary);
}

.editor-container {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    background: var(--bg-secondary);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.2);
}

.editor-panel {
    display: flex;
    flex-direction: column;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: rgba(0, 124, 229, 0.1);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.panel-title {
    font-family: var(--font-heading);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    gap: 0.5rem;
}

.panel-btn {
    background: var(--iisu-red);
    color: var(--iisu-white);
    border: none;
    padding: 0.25rem 0.75rem;
    border-radius: 4px;
    font-size: var(--text-xs);
    cursor: pointer;
    transition: all var(--transition-base);
}

.panel-btn:hover {
    background: #0056B3;
    transform: translateY(-1px);
}

#markdown-input {
    flex: 1;
    padding: 1rem;
    background: var(--bg-primary);
    color: var(--text-primary);
    border: none;
    font-family: 'Courier New', monospace;
    font-size: var(--text-sm);
    resize: none;
    outline: none;
}

.preview-content {
    flex: 1;
    padding: 1rem;
    background: var(--bg-primary);
    color: var(--text-primary);
    overflow-y: auto;
}

.chapters-container {
    padding: 2rem;
}

.chapter-section {
    margin-bottom: 4rem;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.chapter-section.visible {
    opacity: 1;
    transform: translateY(0);
}

.chapter-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid var(--iisu-red);
}

.chapter-number {
    font-family: var(--font-display);
    font-size: var(--text-3xl);
    font-weight: 900;
    color: var(--iisu-red);
    margin: 0;
}

.chapter-title {
    font-family: var(--font-heading);
    font-size: var(--text-2xl);
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.chapter-content {
    display: grid;
    gap: 2rem;
}

.topic-card,
.tool-card,
.syntax-card,
.list-card,
.link-card,
.media-card,
.code-card,
.table-card,
.advanced-card,
.feature-card,
.structure-card,
.dev-card,
.generator-card,
.project-card,
.error-card,
.cheat-card,
.faq-item,
.resource-card,
.expert-card {
    background: var(--bg-secondary);
    border-radius: 12px;
    padding: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
    transition: all var(--transition-base);
}

.topic-card:hover,
.tool-card:hover,
.syntax-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0, 124, 229, 0.2);
}

.topic-title,
.tool-name,
.syntax-title,
.list-title,
.link-title,
.media-title,
.code-title,
.table-title,
.advanced-title,
.feature-title,
.structure-title,
.dev-title,
.generator-title,
.project-title,
.error-title,
.cheat-title,
.faq-question,
.resource-title,
.expert-title {
    font-family: var(--font-heading);
    font-size: var(--text-lg);
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.topic-description,
.tool-description,
.syntax-description,
.list-description,
.link-description,
.media-description,
.code-description,
.table-description,
.advanced-description,
.feature-description,
.structure-description,
.dev-description,
.generator-description,
.project-description,
.error-description,
.faq-answer,
.resource-description,
.expert-description {
    font-family: var(--font-body);
    font-size: var(--text-base);
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1rem;
}

.code-example,
.syntax-example,
.list-example,
.link-example,
.media-example,
.table-example,
.advanced-example,
.structure-example {
    margin-top: 1rem;
}

.example-header,
.syntax-code,
.list-code,
.link-code,
.media-code,
.table-code,
.advanced-code,
.structure-code {
    background: var(--bg-primary);
    padding: 1rem;
    border-radius: 6px;
    font-family: 'Courier New', monospace;
    font-size: var(--text-sm);
    color: var(--text-primary);
    overflow-x: auto;
}

.syntax-result,
.list-result,
.link-result,
.media-result,
.table-result {
    padding: 1rem;
    background: rgba(0, 124, 229, 0.05);
    border-radius: 6px;
    margin-top: 0.5rem;
}

.tools-grid,
.syntax-grid,
.web-generators,
.projects-grid,
.resources-grid,
.cheatsheet-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.tool-icon {
    font-size: var(--text-3xl);
    margin-bottom: 1rem;
}

.tool-steps {
    font-family: var(--font-body);
    font-size: var(--text-sm);
    color: var(--text-secondary);
}

.tool-steps p {
    margin: 0.25rem 0;
}

.topic-list {
    list-style: none;
    padding: 0;
}

.topic-list li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    position: relative;
    padding-left: 1.5rem;
}

.topic-list li::before {
    content: "→";
    position: absolute;
    left: 0;
    color: var(--iisu-red);
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        padding: 1rem 1.5rem;
    }
    
    .brand-name {
        font-size: 1.5rem;
    }
    
    .nav-section {
        gap: 1rem;
    }
    
    .hero-title {
        font-size: clamp(1.5rem, 5vw, 3rem);
    }
    
    .nav-grid {
        grid-template-columns: 1fr;
        gap: 1.5rem;
        padding: 2rem 1.5rem;
    }
    
    .nav-card {
        padding: 2rem 1.5rem;
    }
    
    .nav-icon {
        width: 80px;
        height: 80px;
        font-size: 2rem;
    }
    
    .content-section {
        padding: 6rem 1.5rem 4rem;
    }
    
    .section-title {
        font-size: clamp(2rem, 5vw, 3rem);
    }
    
    .welcome-card {
        padding: 2rem 1.5rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .editor-container {
        grid-template-columns: 1fr;
        height: auto;
    }
    
    .editor-panel {
        height: 400px;
    }
    
    .nav-container {
        gap: 0.5rem;
    }
    
    .nav-button {
        padding: 0.75rem 1rem;
        font-size: 0.75rem;
    }
}