/* Reset and Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #8b5cf6;
    --accent-color: #ec4899;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --gradient-primary: linear-gradient(135deg, #6366f1 0%, #8b5cf6 100%);
    --gradient-accent: linear-gradient(135deg, #ec4899 0%, #f43f5e 100%);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-white);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Sticky Navigation */
.sticky-nav {
    position: sticky;
    top: 0;
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    box-shadow: var(--shadow-sm);
    z-index: 1000;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 70px;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-logo img {
    border-radius: 8px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

.nav-links a:hover {
    color: var(--primary-color);
}

.nav-cta {
    padding: 10px 24px;
    background: var(--gradient-primary);
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    transition: transform 0.2s, box-shadow 0.2s;
}

.nav-cta:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* Hero Section */
.hero {
    padding: 80px 0 60px;
    background: linear-gradient(180deg, #f9fafb 0%, #ffffff 100%);
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    line-height: 1.2;
    text-align: center;
    margin-bottom: 24px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    text-align: center;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 40px;
}

.hero-cta {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 60px;
}

.btn {
    padding: 14px 32px;
    border-radius: 10px;
    text-decoration: none;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.2s;
    display: inline-block;
}

.btn-primary {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-xl);
}

.btn-secondary {
    background: white;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
    background: var(--primary-color);
    color: white;
}

.btn-large {
    padding: 18px 40px;
    font-size: 1.125rem;
}

/* Browser Mockup */
.hero-image {
    max-width: 900px;
    margin: 0 auto;
}

.browser-mockup {
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-xl);
    overflow: hidden;
}

.browser-header {
    background: #e5e7eb;
    padding: 12px 16px;
    display: flex;
    gap: 8px;
}

.dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: #9ca3af;
}

.browser-content {
    padding: 60px 40px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    text-align: center;
}

.demo-text {
    color: white;
    font-size: 1.5rem;
    font-weight: 600;
}

/* Section Styles */
.section {
    padding: 80px 0;
}

.bg-light {
    background-color: var(--bg-light);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.section-intro {
    text-align: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 700px;
    margin: 0 auto 48px;
}

/* Steps */
.steps {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 40px;
    margin-top: 60px;
}

.step {
    text-align: center;
    position: relative;
}

.step-number {
    position: absolute;
    top: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 40px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.25rem;
}

.step-icon {
    font-size: 4rem;
    margin: 30px 0 20px;
}

.step h3 {
    font-size: 1.5rem;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.step p {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Content Blocks */
.content-block {
    margin-bottom: 48px;
}

.content-block h3 {
    font-size: 1.75rem;
    margin-bottom: 20px;
    color: var(--text-primary);
}

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

.requirements-list li {
    padding: 12px 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 1rem;
}

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

code {
    background: #f3f4f6;
    padding: 2px 8px;
    border-radius: 4px;
    font-family: 'Courier New', monospace;
    font-size: 0.9em;
    color: var(--primary-color);
}

/* Setup Steps */
.setup-steps {
    display: flex;
    flex-direction: column;
    gap: 32px;
}

.setup-step {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.setup-step-header {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 20px;
}

.setup-step-number {
    background: var(--gradient-primary);
    color: white;
    padding: 8px 16px;
    border-radius: 8px;
    font-weight: 700;
    font-size: 0.875rem;
}

.setup-step h4 {
    font-size: 1.5rem;
    color: var(--text-primary);
}

.setup-step ol {
    margin-left: 20px;
    margin-top: 16px;
}

.setup-step li {
    margin-bottom: 12px;
    color: var(--text-secondary);
}

.setup-step p {
    margin-top: 20px;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--text-primary);
}

/* Tip Box */
.tip-box {
    background: linear-gradient(135deg, #fef3c7 0%, #fde68a 100%);
    border-left: 4px solid #f59e0b;
    padding: 20px;
    border-radius: 8px;
    margin-top: 24px;
}

.tip-box strong {
    color: #92400e;
}

/* Features Grid */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 32px;
    margin-top: 48px;
    margin-bottom: 60px;
}

.feature-card {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: transform 0.2s, box-shadow 0.2s;
    border: 2px solid transparent;
}

.feature-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.feature-card-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 16px;
}

.feature-icon {
    font-size: 2rem;
}

.feature-card-header h3 {
    font-size: 1.25rem;
    color: var(--text-primary);
    margin: 0;
}

.feature-card p {
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 16px;
}

.feature-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.feature-list li {
    padding: 8px 0;
    padding-left: 24px;
    position: relative;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.feature-list li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* Mini Modes Display */
.mini-modes {
    display: flex;
    gap: 12px;
    margin-top: 16px;
    flex-wrap: wrap;
}

.mini-mode {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    padding: 12px;
    background: var(--bg-light);
    border-radius: 8px;
    flex: 1;
    min-width: 80px;
}

.mini-mode kbd {
    font-size: 1rem;
}

.mini-mode span {
    font-size: 0.85rem;
    color: var(--text-secondary);
}

/* Mini Navigation Demo */
.mini-nav-demo {
    display: flex;
    align-items: center;
    gap: 12px;
    margin: 16px 0;
    padding: 16px;
    background: var(--bg-light);
    border-radius: 8px;
    justify-content: center;
}

.mini-nav-btn {
    padding: 8px 16px;
    background: white;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.9rem;
}

.mini-part {
    padding: 8px 16px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 6px;
    font-weight: 600;
    font-size: 0.85rem;
}

/* Subsection Title */
.subsection-title {
    font-size: 2rem;
    font-weight: 700;
    text-align: center;
    margin: 60px 0 32px;
    color: var(--text-primary);
}

/* Additional Features Grid */
.additional-features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin-top: 32px;
}

.additional-feature-card {
    background: white;
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.additional-feature-header {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 12px;
}

.additional-feature-icon {
    font-size: 1.5rem;
}

.additional-feature-header h4 {
    font-size: 1.1rem;
    color: var(--text-primary);
    margin: 0;
}

.compact-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.compact-list li {
    padding: 6px 0;
    padding-left: 20px;
    position: relative;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.compact-list li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* Highlight Modes */
.highlight-modes {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
    margin: 32px 0;
}

.mode-card {
    background: white;
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.mode-header {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
    margin-bottom: 12px;
}

.mode-icon {
    font-size: 2.5rem;
}

.mode-card h4 {
    font-size: 1.25rem;
    color: var(--text-primary);
}

.mode-card p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.keyboard-hint {
    display: flex;
    gap: 8px;
    justify-content: center;
}

kbd {
    background: #f3f4f6;
    border: 1px solid #d1d5db;
    border-radius: 6px;
    padding: 6px 12px;
    font-family: 'Courier New', monospace;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
    box-shadow: 0 2px 0 #d1d5db;
}

/* Flashcard Types */
.flashcard-types {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin: 32px 0;
}

.flashcard-demo {
    background: white;
    padding: 24px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.flashcard-demo h4 {
    font-size: 1.25rem;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.flashcard-demo ul {
    margin-left: 0;
    list-style-position: inside;
}

/* Navigation Demo */
.navigation-demo {
    margin: 32px 0;
    padding: 40px;
    background: var(--bg-light);
    border-radius: 12px;
    display: flex;
    justify-content: center;
}

.nav-buttons {
    display: flex;
    align-items: center;
    gap: 16px;
}

.nav-btn {
    padding: 12px 24px;
    background: white;
    border: 2px solid var(--primary-color);
    color: var(--primary-color);
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.nav-btn:hover {
    background: var(--primary-color);
    color: white;
}

.part-indicator {
    padding: 12px 24px;
    background: var(--gradient-primary);
    color: white;
    border-radius: 8px;
    font-weight: 600;
}

/* Learning Modes */
.learning-modes {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
    margin: 32px 0;
}

.learning-mode {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.mode-badge {
    font-size: 3rem;
    margin-bottom: 16px;
}

.learning-mode h4 {
    font-size: 1.5rem;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.learning-mode p {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

/* Keyboard Shortcuts */
.shortcuts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 48px;
}

.shortcut-category {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.shortcut-category h3 {
    font-size: 1.5rem;
    margin-bottom: 24px;
    color: var(--text-primary);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 12px;
}

.shortcut-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px 0;
    border-bottom: 1px solid var(--border-color);
}

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

.shortcut-keys {
    display: flex;
    gap: 8px;
}

.shortcut-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Tips Grid */
.tips-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 32px;
    margin-top: 48px;
}

.tip-card {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.tip-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.tip-card h3 {
    font-size: 1.25rem;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.tip-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* FAQ */
.faq-list {
    max-width: 900px;
    margin: 48px auto 0;
}

.faq-item {
    background: white;
    border-radius: 12px;
    margin-bottom: 16px;
    box-shadow: var(--shadow-md);
    overflow: hidden;
}

.faq-question {
    padding: 24px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background 0.2s;
}

.faq-question:hover {
    background: var(--bg-light);
}

.faq-question h3 {
    font-size: 1.125rem;
    color: var(--text-primary);
    margin: 0;
}

.faq-toggle {
    font-size: 1.5rem;
    color: var(--primary-color);
    font-weight: 700;
    transition: transform 0.2s;
}

.faq-item.active .faq-toggle {
    transform: rotate(45deg);
}

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

.faq-item.active .faq-answer {
    max-height: 500px;
}

.faq-answer p {
    padding: 0 24px 24px;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Privacy Grid */
.privacy-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 32px;
    margin-top: 48px;
}

.privacy-card {
    background: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
}

.privacy-icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.privacy-card h3 {
    font-size: 1.25rem;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.privacy-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* CTA Section */
.cta-section {
    background: var(--gradient-primary);
    color: white;
    text-align: center;
}

.cta-section h2 {
    font-size: 2.5rem;
    margin-bottom: 16px;
}

.cta-section p {
    font-size: 1.25rem;
    margin-bottom: 40px;
    opacity: 0.9;
}

.cta-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.cta-section .btn-primary {
    background: white;
    color: var(--primary-color);
}

.cta-section .btn-primary:hover {
    background: var(--bg-light);
}

.cta-section .btn-secondary {
    background: transparent;
    color: white;
    border-color: white;
}

.cta-section .btn-secondary:hover {
    background: white;
    color: var(--primary-color);
}

.cta-note {
    margin-top: 24px;
    font-size: 0.95rem;
    opacity: 0.8;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 48px 0;
    text-align: center;
}

.footer-content {
    max-width: 800px;
    margin: 0 auto;
}

.footer-logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    font-size: 1.5rem;
    font-weight: 700;
    margin-bottom: 16px;
}

.footer-logo img {
    border-radius: 8px;
}

.footer p {
    margin-bottom: 24px;
    opacity: 0.8;
}

.footer-links {
    display: flex;
    gap: 32px;
    justify-content: center;
}

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.2s;
}

.footer-links a:hover {
    opacity: 1;
}

/* Back to Top Button */
.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 50px;
    height: 50px;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: 50%;
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: var(--shadow-lg);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
    z-index: 999;
}

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

.back-to-top:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .section-title {
        font-size: 2rem;
    }

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

    .shortcuts-grid,
    .tips-grid,
    .privacy-grid {
        grid-template-columns: 1fr;
    }

    .cta-buttons {
        flex-direction: column;
    }

    .footer-links {
        flex-direction: column;
        gap: 16px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

    .hero-cta {
        flex-direction: column;
    }

    .btn {
        width: 100%;
        text-align: center;
    }
}