/* ========================================
   Learning OS — Official Website Styles
   ======================================== */

/* --- CSS Custom Properties --- */
:root {
    /* Colors */
    --color-primary: #6366F1;
    --color-primary-light: #818CF8;
    --color-primary-dark: #4F46E5;
    --color-primary-50: #EEF2FF;
    --color-primary-100: #E0E7FF;
    --color-primary-200: #C7D2FE;
    --color-primary-900: #312E81;

    --color-purple: #8B5CF6;
    --color-purple-light: #A78BFA;

    --color-success: #10B981;
    --color-success-light: #D1FAE5;
    --color-warning: #F59E0B;
    --color-warning-light: #FEF3C7;
    --color-error: #EF4444;
    --color-error-light: #FEE2E2;

    /* Neutrals */
    --color-white: #FFFFFF;
    --color-gray-50: #F9FAFB;
    --color-gray-100: #F3F4F6;
    --color-gray-200: #E5E7EB;
    --color-gray-300: #D1D5DB;
    --color-gray-400: #9CA3AF;
    --color-gray-500: #6B7280;
    --color-gray-600: #4B5563;
    --color-gray-700: #374151;
    --color-gray-800: #1F2937;
    --color-gray-900: #111827;
    --color-gray-950: #030712;

    /* Dark section backgrounds */
    --color-dark-bg: #0B0F1A;
    --color-dark-surface: #111827;
    --color-dark-card: rgba(255, 255, 255, 0.04);
    --color-dark-border: rgba(255, 255, 255, 0.08);

    /* Typography */
    --font-sans: 'Inter', 'Noto Sans SC', -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
    --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;

    /* Spacing */
    --section-padding: 120px;
    --container-max: 1200px;
    --container-padding: 24px;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 9999px;

    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.12);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.15);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);

    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;

    /* Z-index */
    --z-nav: 1000;
    --z-modal: 2000;
}

/* --- Reset & Base --- */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    -webkit-text-size-adjust: 100%;
    font-size: 16px;
}

body {
    font-family: var(--font-sans);
    color: var(--color-gray-900);
    background: var(--color-white);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

img { max-width: 100%; height: auto; display: block; }
a { text-decoration: none; color: inherit; }
ul, ol { list-style: none; }
button { cursor: pointer; border: none; background: none; font: inherit; }

/* --- Layout --- */
.container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.section {
    padding: var(--section-padding) 0;
    position: relative;
}

.section-dark {
    background: var(--color-dark-bg);
    color: var(--color-white);
}

.section-dark .section-desc {
    color: var(--color-gray-400);
}

/* --- Section Headers --- */
.section-header {
    text-align: center;
    max-width: 720px;
    margin: 0 auto 72px;
}

.section-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 6px 16px;
    background: var(--color-primary-50);
    color: var(--color-primary);
    font-size: 0.8125rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    margin-bottom: 20px;
    letter-spacing: 0.02em;
}

.section-dark .section-tag {
    background: rgba(99, 102, 241, 0.15);
    color: var(--color-primary-light);
}

.section-title {
    font-size: clamp(1.875rem, 4vw, 2.75rem);
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.025em;
    margin-bottom: 16px;
}

.section-desc {
    font-size: 1.0625rem;
    color: var(--color-gray-500);
    line-height: 1.8;
}

.section-desc strong {
    color: var(--color-gray-800);
    font-weight: 600;
}

.section-dark .section-desc strong {
    color: var(--color-white);
}

/* --- Buttons --- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 16px 32px;
    font-weight: 600;
    font-size: 0.9375rem;
    border-radius: var(--radius-full);
    transition: all var(--transition-base);
    white-space: nowrap;
    cursor: pointer;
    text-decoration: none;
    line-height: 1.4;
    min-height: 48px;
}

.btn-sm {
    padding: 12px 24px;
    font-size: 0.875rem;
    min-height: 42px;
}

.btn-lg {
    padding: 18px 40px;
    font-size: 1rem;
    min-height: 56px;
}

.btn-block {
    width: 100%;
    padding-top: 18px;
    padding-bottom: 18px;
    min-height: 54px;
}

.btn-primary {
    background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
    color: #fff;
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(99, 102, 241, 0.45);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-outline {
    border: 1.5px solid var(--color-gray-300);
    color: var(--color-gray-700);
    background: transparent;
}

.btn-outline:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
    background: var(--color-primary-50);
}

.section-dark .btn-outline {
    border-color: rgba(255, 255, 255, 0.2);
    color: var(--color-white);
}

.section-dark .btn-outline:hover {
    border-color: var(--color-primary-light);
    color: var(--color-primary-light);
    background: rgba(99, 102, 241, 0.1);
}

.btn-ghost {
    color: var(--color-gray-600);
    padding: 10px 16px;
}

.btn-ghost:hover {
    color: var(--color-primary);
    background: var(--color-primary-50);
    border-radius: var(--radius-md);
}


/* ========================================
   Navigation
   ======================================== */
#main-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: var(--z-nav);
    background: rgba(255, 255, 255, 0.8);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid transparent;
    transition: all var(--transition-base);
}

#main-nav.scrolled {
    background: rgba(255, 255, 255, 0.95);
    border-bottom-color: var(--color-gray-200);
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 72px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.125rem;
    color: var(--color-gray-900);
}

.logo-icon {
    display: flex;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: 8px;
}

.nav-link {
    padding: 8px 16px;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-gray-600);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.nav-link:hover {
    color: var(--color-primary);
    background: var(--color-primary-50);
}

.nav-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.mobile-menu-btn {
    display: none;
    flex-direction: column;
    gap: 5px;
    padding: 8px;
}

.mobile-menu-btn span {
    display: block;
    width: 22px;
    height: 2px;
    background: var(--color-gray-700);
    border-radius: 2px;
    transition: all var(--transition-base);
}

.mobile-menu-btn.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}


/* ========================================
   Hero Section
   ======================================== */
#hero-section {
    position: relative;
    padding: 160px 0 80px;
    overflow: hidden;
    background: linear-gradient(180deg, var(--color-primary-50) 0%, var(--color-white) 60%);
}

.hero-bg-effects {
    position: absolute;
    inset: 0;
    pointer-events: none;
    overflow: hidden;
}

.hero-grid {
    position: absolute;
    inset: 0;
    background-image:
        linear-gradient(rgba(99, 102, 241, 0.04) 1px, transparent 1px),
        linear-gradient(90deg, rgba(99, 102, 241, 0.04) 1px, transparent 1px);
    background-size: 60px 60px;
    mask-image: radial-gradient(ellipse at 50% 30%, black 20%, transparent 70%);
    -webkit-mask-image: radial-gradient(ellipse at 50% 30%, black 20%, transparent 70%);
}

.hero-glow {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.4;
}

.hero-glow-1 {
    width: 600px;
    height: 600px;
    background: var(--color-primary-200);
    top: -200px;
    left: -100px;
}

.hero-glow-2 {
    width: 500px;
    height: 500px;
    background: rgba(139, 92, 246, 0.2);
    top: -100px;
    right: -150px;
}

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

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 8px 20px;
    background: rgba(99, 102, 241, 0.1);
    color: var(--color-primary);
    font-size: 0.875rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    margin-bottom: 32px;
    border: 1px solid rgba(99, 102, 241, 0.15);
}

.hero-title {
    font-size: clamp(2.25rem, 5.5vw, 3.75rem);
    font-weight: 900;
    line-height: 1.15;
    letter-spacing: -0.03em;
    margin-bottom: 24px;
    color: var(--color-gray-950);
}

.text-gradient {
    background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.1875rem);
    color: var(--color-gray-500);
    max-width: 640px;
    margin: 0 auto 40px;
    line-height: 1.8;
}

.hero-actions {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 56px;
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 32px;
    margin-bottom: 72px;
    flex-wrap: wrap;
}

.hero-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.stat-number {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-primary);
    font-variant-numeric: tabular-nums;
}

.stat-suffix {
    font-size: 2rem;
    font-weight: 800;
    color: var(--color-primary);
}

.stat-label {
    font-size: 0.8125rem;
    color: var(--color-gray-500);
    font-weight: 500;
}

.hero-stat-divider {
    width: 1px;
    height: 40px;
    background: var(--color-gray-200);
}

/* --- Hero Visual / Window Mock --- */
.hero-visual {
    max-width: 1000px;
    margin: 0 auto;
}

.hero-window {
    background: var(--color-white);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-xl), var(--shadow-glow);
    border: 1px solid var(--color-gray-200);
    overflow: hidden;
}

.window-header {
    display: flex;
    align-items: center;
    padding: 14px 20px;
    background: var(--color-gray-50);
    border-bottom: 1px solid var(--color-gray-200);
    gap: 16px;
}

.window-dots {
    display: flex;
    gap: 8px;
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
}

.dot-red { background: #FF5F57; }
.dot-yellow { background: #FEBC2E; }
.dot-green { background: #28C840; }

.window-title {
    font-size: 0.8125rem;
    color: var(--color-gray-500);
    font-weight: 500;
}

.window-body {
    display: flex;
    min-height: 420px;
}

/* Demo Sidebar */
.demo-sidebar {
    width: 280px;
    min-width: 280px;
    border-right: 1px solid var(--color-gray-200);
    padding: 20px 16px;
    background: var(--color-gray-50);
    display: flex;
    flex-direction: column;
}

.demo-topic-name {
    font-weight: 700;
    font-size: 0.9375rem;
    color: var(--color-gray-900);
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.demo-topic-name i {
    color: var(--color-primary);
}

.demo-nodes {
    display: flex;
    flex-direction: column;
    gap: 4px;
    flex: 1;
}

.demo-node {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 10px 12px;
    border-radius: var(--radius-md);
    font-size: 0.8125rem;
    transition: all var(--transition-fast);
}

.demo-node .node-status-icon {
    font-size: 0.875rem;
    flex-shrink: 0;
    width: 18px;
    text-align: center;
}

.demo-node.verified {
    color: var(--color-gray-700);
}

.demo-node.verified .node-status-icon {
    color: var(--color-success);
}

.demo-node.active {
    background: var(--color-primary-50);
    color: var(--color-primary-dark);
    font-weight: 600;
}

.demo-node.active .node-status-icon {
    color: var(--color-primary);
}

.demo-node.locked {
    color: var(--color-gray-400);
}

.demo-node.locked .node-status-icon {
    color: var(--color-gray-300);
}

.demo-progress {
    height: 4px;
    background: var(--color-gray-200);
    border-radius: 2px;
    margin-top: 20px;
    overflow: hidden;
}

.demo-progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-purple));
    border-radius: 2px;
    transition: width 1s ease;
}

.demo-progress-label {
    font-size: 0.75rem;
    color: var(--color-gray-400);
    margin-top: 8px;
    display: block;
}

/* Demo Main */
.demo-main {
    flex: 1;
    padding: 28px 32px;
    overflow: hidden;
}

.demo-card-header {
    margin-bottom: 24px;
}

.demo-card-badge {
    display: inline-block;
    padding: 4px 12px;
    background: rgba(99, 102, 241, 0.1);
    color: var(--color-primary);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-full);
    font-family: var(--font-mono);
    margin-bottom: 12px;
}

.demo-card-header h3 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.demo-card-objective {
    font-size: 0.875rem;
    color: var(--color-gray-500);
}

.demo-card-section {
    margin-bottom: 20px;
}

.demo-card-section h4 {
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--color-gray-800);
    margin-bottom: 8px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.demo-card-section h4 i {
    color: var(--color-primary);
    font-size: 0.75rem;
}

.demo-card-section p {
    font-size: 0.875rem;
    color: var(--color-gray-600);
    line-height: 1.7;
}

.demo-card-actions {
    margin-top: 24px;
}

.demo-card-actions .btn {
    padding: 16px 32px;
    border-radius: var(--radius-full);
    min-height: 50px;
}


/* ========================================
   Core Value / Pain Points
   ======================================== */
.pain-points-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}

.pain-card {
    padding: 32px 28px;
    border-radius: var(--radius-lg);
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    transition: all var(--transition-base);
}

.pain-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.pain-card-highlight {
    background: linear-gradient(135deg, var(--color-primary-50), rgba(139, 92, 246, 0.05));
    border-color: var(--color-primary-200);
}

.pain-card-highlight:hover {
    box-shadow: var(--shadow-glow), var(--shadow-lg);
}

.pain-icon {
    width: 52px;
    height: 52px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    margin-bottom: 20px;
}

.pain-icon-search { background: #DBEAFE; color: #2563EB; }
.pain-icon-chat { background: #FCE7F3; color: #DB2777; }
.pain-icon-note { background: #FEF3C7; color: #D97706; }
.pain-icon-los { background: var(--color-primary-100); color: var(--color-primary); }

.pain-card h3 {
    font-size: 1.0625rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.pain-solves, .pain-fails {
    font-size: 0.875rem;
    line-height: 1.8;
}

.pain-solves { color: var(--color-success); }
.pain-fails { color: var(--color-error); opacity: 0.8; }

.pain-card-highlight .pain-solves {
    color: var(--color-primary-dark);
    font-weight: 500;
}


/* ========================================
   How It Works / Steps
   ======================================== */
.steps-timeline {
    max-width: 800px;
    margin: 0 auto;
    position: relative;
}

.steps-timeline::before {
    content: '';
    position: absolute;
    left: 42px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: linear-gradient(180deg, var(--color-primary), var(--color-purple), rgba(139, 92, 246, 0.2));
}

.step-item {
    display: flex;
    gap: 32px;
    padding: 0 0 56px 0;
    position: relative;
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.6s ease;
}

.step-item.visible {
    opacity: 1;
    transform: translateY(0);
}

.step-number {
    width: 84px;
    min-width: 84px;
    font-size: 1.5rem;
    font-weight: 800;
    color: rgba(255, 255, 255, 0.15);
    font-family: var(--font-mono);
    text-align: center;
    padding-top: 4px;
    position: relative;
    z-index: 1;
}

.step-content {
    flex: 1;
    background: var(--color-dark-card);
    border: 1px solid var(--color-dark-border);
    border-radius: var(--radius-lg);
    padding: 32px;
    transition: all var(--transition-base);
}

.step-content:hover {
    border-color: rgba(99, 102, 241, 0.3);
    background: rgba(255, 255, 255, 0.06);
}

.step-icon {
    width: 44px;
    height: 44px;
    background: rgba(99, 102, 241, 0.15);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-primary-light);
    font-size: 1.125rem;
    margin-bottom: 16px;
}

.step-content h3 {
    font-size: 1.1875rem;
    font-weight: 700;
    margin-bottom: 10px;
}

.step-content p {
    font-size: 0.9375rem;
    color: var(--color-gray-400);
    line-height: 1.75;
    margin-bottom: 16px;
}

.step-detail {
    margin-top: 12px;
}

.step-detail code {
    display: inline-block;
    padding: 8px 16px;
    background: rgba(99, 102, 241, 0.08);
    color: var(--color-primary-light);
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    border-radius: var(--radius-sm);
    border: 1px solid rgba(99, 102, 241, 0.15);
}

.step-tags {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.step-tag {
    padding: 5px 12px;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 600;
}

.tag-problem { background: rgba(239, 68, 68, 0.15); color: #FCA5A5; }
.tag-concept { background: rgba(59, 130, 246, 0.15); color: #93C5FD; }
.tag-mechanism { background: rgba(99, 102, 241, 0.15); color: #A5B4FC; }
.tag-module { background: rgba(16, 185, 129, 0.15); color: #6EE7B7; }
.tag-optimization { background: rgba(245, 158, 11, 0.15); color: #FCD34D; }

/* Rubric bars in step */
.step-rubric {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 16px;
}

.rubric-item {
    display: flex;
    align-items: center;
    gap: 12px;
}

.rubric-label {
    font-size: 0.8125rem;
    color: var(--color-gray-400);
    width: 64px;
    min-width: 64px;
}

.rubric-bar {
    flex: 1;
    height: 6px;
    background: rgba(255, 255, 255, 0.08);
    border-radius: 3px;
    overflow: hidden;
}

.rubric-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-purple));
    border-radius: 3px;
    transition: width 1s ease;
}


/* ========================================
   Features Section
   ======================================== */
.feature-block {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 72px;
    align-items: center;
    margin-bottom: 120px;
}

.feature-block:last-child {
    margin-bottom: 0;
}

.feature-block-reverse {
    direction: rtl;
}

.feature-block-reverse > * {
    direction: ltr;
}

.feature-tag {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.8125rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 16px;
}

.feature-tag-pro {
    color: var(--color-purple);
}

.pro-badge {
    padding: 2px 8px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
    color: white;
    font-size: 0.6875rem;
    border-radius: var(--radius-full);
    font-weight: 700;
    letter-spacing: 0.05em;
}

.feature-info h3 {
    font-size: 1.75rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.feature-info p {
    font-size: 1rem;
    color: var(--color-gray-500);
    line-height: 1.8;
    margin-bottom: 24px;
}

.feature-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.feature-list li {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    font-size: 0.9375rem;
    color: var(--color-gray-700);
    line-height: 1.5;
}

.feature-list li i {
    color: var(--color-success);
    margin-top: 3px;
    font-size: 0.8125rem;
}

/* --- Chain Demo --- */
.chain-demo {
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-xl);
    padding: 28px;
}

.chain-node-demo {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 18px;
    border-radius: var(--radius-md);
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    transition: all var(--transition-base);
}

.chain-num {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    flex-shrink: 0;
    background: var(--color-gray-100);
    color: var(--color-gray-500);
}

.chain-verified .chain-num {
    background: var(--color-success-light);
    color: var(--color-success);
}

.chain-active .chain-num {
    background: var(--color-primary-100);
    color: var(--color-primary);
}

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

.chain-type {
    font-size: 0.6875rem;
    font-weight: 600;
    color: var(--color-gray-400);
    font-family: var(--font-mono);
    text-transform: uppercase;
}

.chain-title {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-gray-800);
    display: block;
    margin-top: 2px;
}

.chain-locked .chain-title {
    color: var(--color-gray-400);
}

.chain-time {
    font-size: 0.75rem;
    color: var(--color-gray-400);
    font-family: var(--font-mono);
    flex-shrink: 0;
}

.chain-status-icon {
    font-size: 0.875rem;
    flex-shrink: 0;
}

.chain-verified .chain-status-icon { color: var(--color-success); }
.chain-active .chain-status-icon { color: var(--color-primary); }
.chain-locked .chain-status-icon { color: var(--color-gray-300); }

.chain-active {
    border-color: var(--color-primary-200);
    background: var(--color-primary-50);
}

.chain-locked {
    opacity: 0.6;
}

.chain-connector {
    width: 2px;
    height: 16px;
    background: var(--color-success);
    margin: 0 auto;
    border-radius: 1px;
}

.chain-connector-locked {
    background: var(--color-gray-200);
}

/* --- Teach Demo --- */
.teach-demo {
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-xl);
    padding: 28px;
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.teach-task {
    padding: 18px;
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
}

.teach-task-header, .teach-response-header {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-gray-500);
    margin-bottom: 10px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.teach-task-header i { color: var(--color-primary); }
.teach-response-header i { color: var(--color-gray-400); }

.teach-task p {
    font-size: 0.9375rem;
    color: var(--color-gray-700);
    line-height: 1.7;
}

.teach-response {
    padding: 18px;
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
}

.teach-answer-preview {
    font-size: 0.875rem;
    color: var(--color-gray-500);
    line-height: 1.7;
    font-style: italic;
}

.teach-feedback {
    padding: 18px;
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
}

.teach-verdict {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 14px;
    padding-bottom: 14px;
    border-bottom: 1px solid var(--color-gray-100);
}

.verdict-retry {
    color: var(--color-warning);
}

.teach-score {
    margin-left: auto;
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    padding: 3px 10px;
    background: var(--color-warning-light);
    border-radius: var(--radius-sm);
    color: var(--color-warning);
}

.teach-feedback-items {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 14px;
}

.feedback-item {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.8125rem;
    line-height: 1.5;
}

.feedback-item i {
    margin-top: 2px;
    font-size: 0.75rem;
}

.feedback-strength i { color: var(--color-success); }
.feedback-gap i { color: var(--color-warning); }
.feedback-error i { color: var(--color-error); }

.feedback-strength span { color: var(--color-gray-700); }
.feedback-gap span { color: var(--color-gray-600); }
.feedback-error span { color: var(--color-error); }

.teach-followup {
    padding: 12px 16px;
    background: var(--color-primary-50);
    border-radius: var(--radius-sm);
    font-size: 0.8125rem;
    color: var(--color-primary-dark);
    display: flex;
    align-items: flex-start;
    gap: 10px;
    line-height: 1.6;
}

.teach-followup i {
    margin-top: 3px;
    color: var(--color-primary);
}

/* --- Review Demo --- */
.review-demo {
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-xl);
    padding: 28px;
}

.review-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 20px;
}

.review-header h4 {
    font-size: 1rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 10px;
}

.review-header h4 i {
    color: var(--color-primary);
}

.review-time {
    font-size: 0.8125rem;
    color: var(--color-gray-400);
    font-family: var(--font-mono);
}

.review-items {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 20px;
}

.review-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 16px;
    background: var(--color-white);
    border-radius: var(--radius-md);
    border: 1px solid var(--color-gray-200);
}

.review-item-left {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.review-reason {
    font-size: 0.6875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--color-gray-400);
}

.review-urgent .review-reason {
    color: var(--color-error);
}

.review-node-name {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--color-gray-800);
}

.review-item-right {
    display: flex;
    align-items: center;
    gap: 12px;
}

.mastery-score {
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 700;
    font-family: var(--font-mono);
}

.mastery-low {
    background: var(--color-error-light);
    color: var(--color-error);
}

.mastery-mid {
    background: var(--color-warning-light);
    color: var(--color-warning);
}

.review-est {
    font-size: 0.75rem;
    color: var(--color-gray-400);
    font-family: var(--font-mono);
}

.review-actions {
    display: flex;
    gap: 12px;
}

/* --- Analytics Demo --- */
.analytics-demo {
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-xl);
    padding: 28px;
}

.analytics-overview {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
    margin-bottom: 24px;
}

.analytics-card {
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    padding: 18px 16px;
    text-align: center;
}

.analytics-value {
    display: block;
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--color-primary);
    font-variant-numeric: tabular-nums;
}

.analytics-label {
    display: block;
    font-size: 0.75rem;
    color: var(--color-gray-500);
    margin-top: 4px;
}

.analytics-chart {
    background: var(--color-white);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    padding: 20px;
}

.analytics-chart h4 {
    font-size: 0.875rem;
    font-weight: 700;
    margin-bottom: 20px;
    color: var(--color-gray-800);
}

.radar-placeholder {
    display: flex;
    flex-direction: column;
    gap: 14px;
    padding: 4px 0;
}

.radar-axis {
    display: flex;
    align-items: center;
    gap: 12px;
}

.radar-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--color-primary);
    flex-shrink: 0;
}

.radar-label-text {
    font-size: 0.8125rem;
    color: var(--color-gray-600);
    min-width: 100px;
}

.radar-bar-track {
    flex: 1;
    height: 8px;
    background: var(--color-gray-100);
    border-radius: 4px;
    overflow: hidden;
}

.radar-bar-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-purple));
    border-radius: 4px;
    transition: width 1s ease;
}


/* ========================================
   Use Cases
   ======================================== */
.use-cases-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.use-case-card {
    background: var(--color-dark-card);
    border: 1px solid var(--color-dark-border);
    border-radius: var(--radius-xl);
    padding: 36px;
    transition: all var(--transition-base);
}

.use-case-card:hover {
    border-color: rgba(99, 102, 241, 0.3);
    transform: translateY(-4px);
}

.use-case-icon {
    width: 52px;
    height: 52px;
    background: rgba(99, 102, 241, 0.15);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    color: var(--color-primary-light);
    margin-bottom: 20px;
}

.use-case-card h3 {
    font-size: 1.125rem;
    font-weight: 700;
    margin-bottom: 12px;
}

.use-case-scenario {
    font-size: 0.9375rem;
    color: var(--color-gray-400);
    line-height: 1.7;
    margin-bottom: 20px;
    font-style: italic;
}

.use-case-topic {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 18px;
}

.use-case-topic span {
    font-size: 0.75rem;
    color: var(--color-gray-500);
    font-weight: 500;
}

.use-case-topic code {
    padding: 6px 14px;
    background: rgba(99, 102, 241, 0.1);
    color: var(--color-primary-light);
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    border-radius: var(--radius-sm);
    border: 1px solid rgba(99, 102, 241, 0.15);
}

.use-case-benefits {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.use-case-benefits li {
    font-size: 0.875rem;
    color: var(--color-gray-300);
    padding-left: 20px;
    position: relative;
}

.use-case-benefits li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--color-primary-light);
}


/* ========================================
   Pricing Section
   ======================================== */
.pricing-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    margin-bottom: 56px;
}

.toggle-label {
    font-size: 0.9375rem;
    font-weight: 500;
    color: var(--color-gray-500);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    user-select: none;
}

.toggle-label.active {
    color: var(--color-gray-900);
    font-weight: 600;
}

.toggle-discount {
    padding: 3px 10px;
    background: var(--color-success-light);
    color: var(--color-success);
    font-size: 0.75rem;
    font-weight: 600;
    border-radius: var(--radius-full);
}

.toggle-switch {
    width: 52px;
    height: 28px;
    background: var(--color-gray-200);
    border-radius: var(--radius-full);
    position: relative;
    transition: background var(--transition-base);
    cursor: pointer;
}

.toggle-switch.active {
    background: var(--color-primary);
}

.toggle-slider {
    position: absolute;
    top: 3px;
    left: 3px;
    width: 22px;
    height: 22px;
    background: var(--color-white);
    border-radius: 50%;
    transition: transform var(--transition-base);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}

.toggle-switch.active .toggle-slider {
    transform: translateX(24px);
}

.pricing-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
    max-width: 900px;
    margin: 0 auto;
}

.pricing-card {
    background: var(--color-white);
    border: 1.5px solid var(--color-gray-200);
    border-radius: var(--radius-xl);
    padding: 40px 36px;
    position: relative;
    transition: all var(--transition-base);
}

.pricing-card:hover {
    box-shadow: var(--shadow-lg);
}

.pricing-card-featured {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-glow);
}

.pricing-card-featured:hover {
    box-shadow: var(--shadow-glow), var(--shadow-lg);
}

.pricing-popular {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    padding: 6px 20px;
    background: linear-gradient(135deg, var(--color-primary), var(--color-purple));
    color: var(--color-white);
    font-size: 0.75rem;
    font-weight: 700;
    border-radius: var(--radius-full);
    letter-spacing: 0.03em;
}

.pricing-header {
    text-align: center;
    margin-bottom: 32px;
    padding-bottom: 32px;
    border-bottom: 1px solid var(--color-gray-100);
}

.pricing-name {
    font-size: 1.5rem;
    font-weight: 800;
    margin-bottom: 4px;
}

.pricing-tagline {
    font-size: 0.875rem;
    color: var(--color-gray-500);
    margin-bottom: 20px;
}

.pricing-price {
    display: flex;
    align-items: baseline;
    justify-content: center;
    gap: 4px;
}

.price-amount {
    font-size: 3rem;
    font-weight: 900;
    color: var(--color-gray-900);
    line-height: 1;
    letter-spacing: -0.03em;
}

.price-period {
    font-size: 0.875rem;
    color: var(--color-gray-400);
}

.pricing-features {
    margin-bottom: 32px;
}

.pricing-feature-group {
    margin-bottom: 24px;
}

.pricing-feature-group:last-child {
    margin-bottom: 0;
}

.pricing-feature-group h4 {
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--color-gray-400);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 12px;
}

.pricing-feature-group ul {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.pricing-feature-group li {
    display: flex;
    align-items: flex-start;
    gap: 10px;
    font-size: 0.875rem;
    line-height: 1.5;
}

.pricing-feature-group li i {
    margin-top: 3px;
    font-size: 0.75rem;
}

.feature-included i { color: var(--color-success); }
.feature-limited i { color: var(--color-gray-400); }
.feature-limited { color: var(--color-gray-500); }
.feature-highlight { font-weight: 600; color: var(--color-primary-dark); }
.feature-highlight i.fa-star { color: var(--color-primary); }

.pricing-action {
    text-align: center;
}

.pricing-action .btn {
    padding: 18px 32px;
    font-size: 1rem;
    border-radius: var(--radius-full);
}

.pricing-note {
    font-size: 0.8125rem;
    color: var(--color-gray-400);
    margin-top: 12px;
}

/* BYOK Note */
.byok-note {
    display: flex;
    gap: 24px;
    align-items: flex-start;
    max-width: 900px;
    margin: 48px auto 0;
    padding: 28px 32px;
    background: var(--color-gray-50);
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-lg);
}

.byok-icon {
    width: 48px;
    height: 48px;
    background: var(--color-primary-100);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-primary);
    font-size: 1.125rem;
    flex-shrink: 0;
}

.byok-content h4 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.byok-content p {
    font-size: 0.9375rem;
    color: var(--color-gray-500);
    line-height: 1.7;
}

.byok-content strong {
    color: var(--color-gray-800);
}


/* ========================================
   Templates Section
   ======================================== */
.templates-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
}

.template-card {
    background: var(--color-dark-card);
    border: 1px solid var(--color-dark-border);
    border-radius: var(--radius-lg);
    padding: 24px;
    text-align: center;
    transition: all var(--transition-base);
    position: relative;
}

.template-card:hover {
    border-color: rgba(99, 102, 241, 0.3);
    transform: translateY(-4px);
    background: rgba(255, 255, 255, 0.06);
}

.template-icon {
    width: 44px;
    height: 44px;
    margin: 0 auto 14px;
    background: rgba(99, 102, 241, 0.12);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-primary-light);
    font-size: 1.125rem;
}

.template-card h4 {
    font-size: 0.9375rem;
    font-weight: 700;
    margin-bottom: 4px;
}

.template-card p {
    font-size: 0.75rem;
    color: var(--color-gray-500);
}

.template-badge {
    position: absolute;
    top: 12px;
    right: 12px;
    padding: 3px 8px;
    font-size: 0.625rem;
    font-weight: 700;
    border-radius: var(--radius-full);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.template-free {
    background: rgba(16, 185, 129, 0.15);
    color: var(--color-success);
}

.template-pro {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(139, 92, 246, 0.2));
    color: var(--color-primary-light);
}


/* ========================================
   Download / CTA Section
   ======================================== */
.download-block {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 64px;
    align-items: center;
}

.download-content h2 {
    font-size: clamp(1.75rem, 3vw, 2.25rem);
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 16px;
    letter-spacing: -0.02em;
}

.download-content p {
    font-size: 1rem;
    color: var(--color-gray-500);
    line-height: 1.8;
    margin-bottom: 32px;
}

.download-actions {
    display: flex;
    gap: 16px;
    margin-bottom: 24px;
    flex-wrap: wrap;
}

.download-requirements {
    display: flex;
    gap: 24px;
    flex-wrap: wrap;
}

.download-requirements span {
    font-size: 0.8125rem;
    color: var(--color-gray-500);
    display: flex;
    align-items: center;
    gap: 6px;
}

.download-requirements i {
    color: var(--color-success);
    font-size: 0.75rem;
}

/* Obsidian Mockup */
.obsidian-mockup {
    background: #1e1e2e;
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-xl);
    display: flex;
    min-height: 360px;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

.obsidian-sidebar {
    width: 220px;
    min-width: 220px;
    background: #181825;
    padding: 16px 12px;
    border-right: 1px solid rgba(255, 255, 255, 0.06);
}

.obsidian-vault-name {
    font-size: 0.8125rem;
    font-weight: 600;
    color: #cdd6f4;
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 16px;
    padding: 8px 12px;
}

.obsidian-vault-name i {
    color: #89b4fa;
}

.obsidian-folder {
    font-size: 0.8125rem;
    color: #bac2de;
    padding-left: 12px;
}

.obsidian-folder > i {
    color: #f9e2af;
    margin-right: 6px;
}

.obsidian-files {
    padding-top: 8px;
    padding-left: 20px;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.obsidian-file {
    font-size: 0.75rem;
    color: #a6adc8;
    padding: 6px 10px;
    border-radius: 4px;
    display: flex;
    align-items: center;
    gap: 8px;
}

.obsidian-file i { color: #74c7ec; font-size: 0.6875rem; }

.obsidian-file.active {
    background: rgba(137, 180, 250, 0.15);
    color: #89b4fa;
}

.obsidian-content {
    flex: 1;
    padding: 24px;
    color: #cdd6f4;
}

.obsidian-breadcrumb {
    font-size: 0.6875rem;
    color: #6c7086;
    margin-bottom: 16px;
}

.obsidian-content h3 {
    font-size: 1.125rem;
    color: #cdd6f4;
    margin-bottom: 16px;
    font-weight: 700;
}

.obsidian-stats {
    display: flex;
    gap: 24px;
    margin-bottom: 16px;
    font-size: 0.8125rem;
}

.obsidian-stats span {
    color: #a6adc8;
}

.obsidian-summary {
    font-size: 0.8125rem;
    color: #bac2de;
    line-height: 1.8;
}


/* ========================================
   FAQ Section
   ======================================== */
.faq-grid {
    max-width: 800px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.faq-question {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    font-size: 0.9375rem;
    font-weight: 600;
    color: var(--color-gray-900);
    text-align: left;
    gap: 16px;
    cursor: pointer;
    transition: background var(--transition-fast);
}

.faq-question:hover {
    background: rgba(0, 0, 0, 0.02);
}

.faq-question i {
    font-size: 0.75rem;
    color: var(--color-gray-400);
    transition: transform var(--transition-base);
    flex-shrink: 0;
}

.faq-item.active .faq-question i {
    transform: rotate(180deg);
    color: var(--color-primary-light);
}

.faq-answer {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease, opacity 0.3s ease;
    opacity: 0;
}

.faq-item.active .faq-answer {
    max-height: 800px;
    opacity: 1;
}

.faq-answer p {
    padding: 0 24px 20px;
    font-size: 0.9375rem;
    color: var(--color-gray-500);
    line-height: 1.8;
}

.faq-answer strong {
    color: var(--color-gray-800);
    font-weight: 600;
}

.faq-item {
    border: 1px solid var(--color-gray-200);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: border-color var(--transition-base);
}

.faq-item.active {
    border-color: var(--color-primary-200);
}


/* ========================================
   Final CTA
   ======================================== */
.final-cta-block {
    text-align: center;
    padding: 80px 40px;
    background: rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-xl);
    box-shadow: var(--shadow-lg);
}

.final-cta-block h2 {
    font-size: clamp(1.5rem, 3vw, 2.25rem);
    font-weight: 800;
    margin-bottom: 12px;
    letter-spacing: -0.02em;
    color: var(--color-gray-900);
}

.final-cta-block p {
    font-size: 1.0625rem;
    color: var(--color-gray-500);
    margin-bottom: 32px;
}

.final-cta-actions {
    margin-bottom: 24px;
}

.trust-signals {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 32px;
    flex-wrap: wrap;
}

.trust-signals span {
    font-size: 0.8125rem;
    color: var(--color-gray-400);
    display: flex;
    align-items: center;
    gap: 8px;
}

.trust-signals i {
    color: var(--color-primary);
}


/* ========================================
   Footer
   ======================================== */
#site-footer {
    padding: 64px 0 32px;
    background: var(--color-gray-950);
    color: var(--color-gray-400);
}

.footer-grid {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1fr;
    gap: 48px;
    margin-bottom: 48px;
}

.footer-brand {
    max-width: 280px;
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.0625rem;
    color: var(--color-white);
    margin-bottom: 16px;
}

.footer-brand p {
    font-size: 0.875rem;
    line-height: 1.7;
}

.footer-links-group h4 {
    font-size: 0.8125rem;
    font-weight: 700;
    color: var(--color-white);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 16px;
}

.footer-links-group li {
    margin-bottom: 10px;
}

.footer-links-group a {
    font-size: 0.875rem;
    color: var(--color-gray-400);
    transition: color var(--transition-fast);
    display: flex;
    align-items: center;
    gap: 8px;
}

.footer-links-group a:hover {
    color: var(--color-white);
}

.footer-bottom {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-top: 32px;
    border-top: 1px solid rgba(255, 255, 255, 0.06);
}


/* ========================================
   Mobile Responsive — @media (max-width: 768px)
   ======================================== */
@media (max-width: 768px) {

    /* --- Layout Overrides --- */
    :root {
        --section-padding: 64px;
        --container-padding: 16px;
    }

    .section {
        padding: var(--section-padding) 0;
    }

    .section-header {
        margin-bottom: 48px;
    }

    /* --- Navigation Mobile Panel --- */
    .nav-container {
        height: 60px;
        justify-content: flex-start;
    }

    .nav-logo {
        margin-right: auto;
    }

    .nav-links {
        position: fixed;
        top: 60px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        -webkit-backdrop-filter: blur(20px);
        backdrop-filter: blur(20px);
        border-bottom: 1px solid var(--color-gray-200);
        flex-direction: column;
        align-items: stretch;
        padding: 16px var(--container-padding);
        gap: 4px;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all var(--transition-base);
        z-index: calc(var(--z-nav) - 1);
    }

    .nav-links.open {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-link {
        padding: 14px 16px;
        font-size: 1rem;
        border-radius: var(--radius-md);
    }

    .nav-actions {
        gap: 8px;
        margin-left: auto;
        flex-shrink: 0;
    }


    .mobile-menu-btn {
        display: flex;
    }

    #main-nav {
        background: rgba(255, 255, 255, 0.95);
    }

    #main-nav.scrolled {
        background: rgba(255, 255, 255, 0.98);
    }

    /* --- Hero Section --- */
    #hero-section {
        padding: 100px 0 48px;
    }

    .hero-badge {
        padding: 6px 14px;
        font-size: 0.8125rem;
        margin-bottom: 24px;
    }

    .hero-title {
        font-size: clamp(1.75rem, 7vw, 2.5rem);
        margin-bottom: 16px;
    }

    .hero-subtitle {
        font-size: 0.9375rem;
        margin-bottom: 28px;
        line-height: 1.7;
    }

    .hero-actions {
        gap: 12px;
        margin-bottom: 36px;
    }

    .hero-actions .btn-lg {
        padding: 14px 28px;
        font-size: 0.9375rem;
        min-height: 48px;
        width: 100%;
    }

    /* --- Pain Points Grid --- */
    .pain-points-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 16px;
    }

    .pain-card {
        padding: 24px 20px;
    }

    .pain-icon {
        width: 44px;
        height: 44px;
        font-size: 1rem;
        margin-bottom: 14px;
    }

    .pain-card h3 {
        font-size: 0.9375rem;
        margin-bottom: 10px;
    }

    .pain-fails, .pain-solution {
        font-size: 0.8125rem;
    }

    /* --- Feature Blocks --- */
    .feature-block {
        grid-template-columns: 1fr;
        gap: 32px;
        margin-bottom: 64px;
    }

    .feature-block-reverse {
        direction: ltr;
    }

    .feature-info h3 {
        font-size: 1.375rem;
    }

    .feature-info p {
        font-size: 0.9375rem;
    }

    /* --- Chain Demo --- */
    .chain-demo {
        padding: 20px;
    }

    .chain-node-demo {
        padding: 12px 14px;
        gap: 10px;
    }

    .chain-info {
        min-width: 0;
    }

    .chain-title {
        font-size: 0.8125rem;
    }

    .chain-time {
        display: none;
    }

    /* --- Teach Demo --- */
    .teach-demo {
        padding: 20px;
    }

    .teach-score {
        font-size: 0.75rem;
        padding: 2px 8px;
    }

    /* --- Review Demo --- */
    .review-demo {
        padding: 20px;
    }

    .review-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .review-item-right {
        width: 100%;
        justify-content: space-between;
    }

    /* --- Use Cases Grid --- */
    .use-cases-grid {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .use-case-card {
        padding: 24px;
    }

    /* --- Pricing Grid --- */
    .pricing-grid {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .pricing-card {
        padding: 32px 24px;
    }

    .pricing-popular {
        top: -10px;
    }

    .price-amount {
        font-size: 2.5rem;
    }

    .pricing-toggle {
        margin-bottom: 40px;
    }

    .byok-note {
        flex-direction: column;
        gap: 16px;
        padding: 20px;
    }

    /* --- Download Block --- */
    .download-block {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .download-content h2 {
        font-size: 1.5rem;
    }

    .download-content p {
        font-size: 0.9375rem;
        margin-bottom: 24px;
    }

    .download-actions {
        flex-direction: column;
        gap: 12px;
    }

    .download-actions .btn-lg {
        width: 100%;
        justify-content: center;
    }

    .download-requirements {
        flex-direction: column;
        gap: 8px;
    }

    /* --- Obsidian Mockup (critical fix) --- */
    .obsidian-mockup {
        flex-direction: column;
        min-height: auto;
    }

    .obsidian-sidebar {
        display: none;
    }

    .obsidian-content {
        padding: 16px;
    }

    .obsidian-stats {
        flex-wrap: wrap;
        gap: 12px;
    }

    /* --- Window Demo --- */
    .window-body {
        flex-direction: column;
        min-height: auto;
    }

    .demo-sidebar {
        width: 100%;
        min-width: 0;
        border-right: none;
        border-bottom: 1px solid var(--color-gray-200);
        padding: 16px;
        max-height: 200px;
        overflow-y: auto;
    }

    .demo-nodes {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 8px;
    }

    .demo-node {
        padding: 8px 12px;
    }

    .demo-main {
        padding: 20px;
    }

    /* --- FAQ --- */
    .faq-question {
        padding: 16px 18px;
        font-size: 0.875rem;
    }

    .faq-answer p {
        padding: 0 18px 16px;
        font-size: 0.875rem;
    }

    /* --- Footer --- */
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .footer-brand {
        max-width: 100%;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }

    /* --- Section Title --- */
    .section-title {
        font-size: clamp(1.5rem, 5vw, 2rem);
    }

    .section-desc {
        font-size: 0.9375rem;
    }

    /* --- Buttons mobile --- */
    .btn-lg {
        padding: 14px 28px;
        font-size: 0.9375rem;
        min-height: 48px;
    }

    .btn-block {
        padding-top: 14px;
        padding-bottom: 14px;
    }

    /* --- Analytics grid --- */
    .analytics-overview {
        grid-template-columns: repeat(3, 1fr);
        gap: 8px;
    }

    .analytics-value {
        font-size: 1.25rem;
    }

    /* --- Final CTA --- */
    .final-cta-block {
        padding: 48px 24px;
    }

    .trust-signals {
        flex-direction: column;
        gap: 12px;
    }
}

/* --- Extra small screens (≤480px) --- */
@media (max-width: 480px) {
    :root {
        --section-padding: 48px;
        --container-padding: 12px;
    }

    .pain-points-grid {
        grid-template-columns: 1fr;
    }

    .hero-title {
        font-size: 1.625rem;
    }

    .hero-subtitle {
        font-size: 0.875rem;
    }

    .method-card {
        padding: 20px;
    }

    .method-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .method-number {
        font-size: 28px;
    }

    .method-icon-large {
        width: 40px;
        height: 40px;
        font-size: 18px;
    }

    .method-name {
        font-size: 18px;
    }

    .pricing-card {
        padding: 24px 18px;
    }
}

.footer-bottom p {
    font-size: 0.8125rem;
}

.footer-legal {
    display: flex;
    gap: 24px;
}

.footer-legal a {
    font-size: 0.8125rem;
    color: var(--color-gray-500);
    transition: color var(--transition-fast);
}

.footer-legal a:hover {
    color: var(--color-white);
}


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

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: all 0.7s ease;
}

.animate-on-scroll.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Stagger children */
.animate-stagger > * {
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.5s ease;
}

.animate-stagger.visible > *:nth-child(1) { transition-delay: 0ms; }
.animate-stagger.visible > *:nth-child(2) { transition-delay: 80ms; }
.animate-stagger.visible > *:nth-child(3) { transition-delay: 160ms; }
.animate-stagger.visible > *:nth-child(4) { transition-delay: 240ms; }

.animate-stagger.visible > * {
    opacity: 1;
    transform: translateY(0);
}


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

/* Tablet / Early mobile: switch nav to hamburger before content squeezes */
@media (max-width: 1024px) {
    :root {
        --section-padding: 80px;
    }

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

    .feature-block {
        grid-template-columns: 1fr;
        gap: 48px;
    }

    .feature-block-reverse {
        direction: ltr;
    }

    .templates-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .download-block {
        grid-template-columns: 1fr;
        gap: 48px;
    }

    .footer-grid {
        grid-template-columns: 1fr 1fr;
        gap: 36px;
    }

    /* Nav: switch to mobile layout early to avoid squeeze */
    .nav-container {
        justify-content: flex-start;
    }

    .nav-logo {
        margin-right: auto;
    }

    .nav-links {
        display: none;
        position: fixed;
        top: 72px;
        left: 0;
        right: 0;
        background: rgba(255, 255, 255, 0.98);
        backdrop-filter: blur(20px);
        -webkit-backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 16px 20px;
        border-bottom: 1px solid var(--color-gray-200);
        box-shadow: var(--shadow-lg);
    }

    .nav-links.open {
        display: flex;
    }

    .nav-link {
        padding: 12px 16px;
        width: 100%;
    }


    .nav-actions {
        margin-left: auto;
        flex-shrink: 0;
    }

    .mobile-menu-btn {
        display: flex;
    }
}

/* Mobile */
@media (max-width: 768px) {
    :root {
        --section-padding: 64px;
        --container-padding: 20px;
    }

    /* Hero */
    #hero-section {
        padding: 120px 0 60px;
    }

    .hero-title {
        font-size: clamp(1.75rem, 7vw, 2.5rem);
    }

    .hero-actions {
        flex-direction: column;
        align-items: stretch;
    }

    .hero-actions .btn {
        width: 100%;
    }

    .hero-stats {
        gap: 20px;
    }

    .hero-stat-divider {
        display: none;
    }

    /* Hero Window */
    .window-body {
        flex-direction: column;
    }

    .demo-sidebar {
        width: 100%;
        min-width: 100%;
        border-right: none;
        border-bottom: 1px solid var(--color-gray-200);
        padding: 16px;
    }

    .demo-main {
        padding: 20px;
    }

    /* Pain Points */
    .pain-points-grid {
        grid-template-columns: 1fr;
    }

    /* Steps */
    .steps-timeline::before {
        left: 20px;
    }

    .step-item {
        flex-direction: column;
        gap: 0;
    }

    .step-number {
        width: auto;
        min-width: auto;
        text-align: left;
        padding-left: 48px;
        margin-bottom: 12px;
    }

    .step-content {
        margin-left: 0;
        padding: 24px;
    }

    /* Features */
    .feature-block {
        gap: 36px;
        margin-bottom: 80px;
    }

    .feature-info h3 {
        font-size: 1.375rem;
    }

    /* Use Cases */
    .use-cases-grid {
        grid-template-columns: 1fr;
    }

    /* Pricing */
    .pricing-grid {
        grid-template-columns: 1fr;
    }

    .byok-note {
        flex-direction: column;
        align-items: center;
        text-align: center;
    }

    /* Templates */
    .templates-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    /* Download */
    .download-actions {
        flex-direction: column;
    }

    .download-actions .btn {
        width: 100%;
    }

    .obsidian-mockup {
        flex-direction: column;
    }

    .obsidian-sidebar {
        width: 100%;
        min-width: 100%;
        border-right: none;
        border-bottom: 1px solid rgba(255, 255, 255, 0.06);
    }

    /* FAQ */
    .faq-question {
        padding: 16px 20px;
        font-size: 0.875rem;
    }

    .faq-answer p {
        padding: 0 20px 16px;
        font-size: 0.875rem;
    }

    /* Footer */
    .footer-grid {
        grid-template-columns: 1fr;
        gap: 32px;
    }

    .footer-brand {
        max-width: 100%;
    }

    .footer-bottom {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }

    /* Final CTA */
    .final-cta-block {
        padding: 48px 24px;
    }

    .trust-signals {
        gap: 16px;
    }
}

/* Small Mobile */
@media (max-width: 480px) {
    .hero-title {
        font-size: 1.75rem;
    }

    .templates-grid {
        grid-template-columns: 1fr;
    }

    .analytics-overview {
        grid-template-columns: 1fr;
    }

    .review-item {
        flex-direction: column;
        align-items: flex-start;
        gap: 12px;
    }

    .review-item-right {
        width: 100%;
        justify-content: flex-start;
    }

    .obsidian-stats {
        flex-direction: column;
        gap: 8px;
    }
}