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

:root {
    --rust-orange: #f74c00;
    --rust-orange-dark: #c43e00;
    --rust-orange-light: #ff6b1a;
    --bg-dark: #0d1117;
    --bg-darker: #010409;
    --bg-card: #161b22;
    --bg-card-hover: #1f2937;
    --text-primary: #f0f6fc;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    --border-color: #30363d;
    --accent-gradient: linear-gradient(135deg, #f74c00 0%, #ff8c42 100%);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.5);
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
}

html {
    scroll-behavior: smooth;
}

.hero-layout {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    gap: 60px;
    padding: 120px 40px 80px 80px;
    position: relative;
    z-index: 1;
}

.book {
    border: none;
    flex-shrink: 0;
    pointer-events: none;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg-dark);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navigation */
.nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 40px;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.nav-links {
    display: flex;
    gap: 32px;
    align-items: center;
}

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

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px 20px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.95rem;
    text-decoration: none;
    transition: all 0.2s ease;
    cursor: pointer;
    border: none;
}

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

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

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

.btn-secondary:hover {
    border-color: var(--rust-orange);
    color: var(--rust-orange);
}

.btn-large {
    padding: 16px 32px;
    font-size: 1.1rem;
}

/* Hero Section */
.hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    background: var(--bg-darker);
    background-image:
        radial-gradient(ellipse at 20% 80%, rgba(247, 76, 0, 0.15) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 20%, rgba(247, 76, 0, 0.1) 0%, transparent 50%);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background:
        linear-gradient(90deg, transparent 0%, transparent 50%, rgba(247, 76, 0, 0.02) 50%, rgba(247, 76, 0, 0.02) 100%);
    background-size: 4px 4px;
    pointer-events: none;
}

.hero-content {
    text-align: center;
    max-width: 600px;
}

.hero-badge {
    display: inline-block;
    padding: 8px 16px;
    background: rgba(247, 76, 0, 0.15);
    border: 1px solid rgba(247, 76, 0, 0.3);
    border-radius: 50px;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--rust-orange-light);
    margin-bottom: 24px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.hero h1 {
    font-size: clamp(3rem, 8vw, 5rem);
    font-weight: 700;
    margin-bottom: 24px;
    background: linear-gradient(135deg, var(--text-primary) 0%, var(--rust-orange-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 40px;
    line-height: 1.7;
}

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

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 60px;
    flex-wrap: wrap;
}

.stat {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--rust-orange);
    font-family: 'JetBrains Mono', monospace;
}

.stat-label {
    font-size: 0.875rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* Sections */
.section {
    padding: 100px 0;
}

.section-alt {
    background: var(--bg-darker);
}

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

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.125rem;
    max-width: 600px;
    margin: 0 auto 60px;
}

/* Chapters Grid */
.chapters-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.chapter-category {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 28px;
    transition: all 0.3s ease;
}

.chapter-category:hover {
    border-color: rgba(247, 76, 0, 0.4);
    box-shadow: 0 0 30px rgba(247, 76, 0, 0.1);
}

.category-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--rust-orange);
    margin-bottom: 20px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border-color);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

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

.chapter-list li {
    padding: 10px 0;
    color: var(--text-secondary);
    font-size: 0.95rem;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    border-bottom: 1px solid rgba(48, 54, 61, 0.5);
    transition: color 0.2s ease;
}

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

.chapter-list li:hover {
    color: var(--text-primary);
}

.chapter-list a:any-link,
.chapter-list a:-webkit-any-link,
.chapter-list a,
.chapter-list a:link,
.chapter-list a:visited,
.chapter-list a:hover,
.chapter-list a:active,
.chapter-list li a:any-link,
.chapter-list li a:-webkit-any-link,
.chapter-list li a,
.chapter-list li a:link,
.chapter-list li a:visited,
.chapter-list li a:hover,
.chapter-list li a:active {
    color: #8b949e !important;
    -webkit-text-fill-color: #8b949e !important;
    text-decoration: none !important;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    width: 100%;
}

.chapter-list a {
    all: unset;
    color: #8b949e !important;
    -webkit-text-fill-color: #8b949e !important;
    cursor: pointer;
    display: flex;
    align-items: flex-start;
    gap: 12px;
    width: 100%;
}

.chapter-num {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--rust-orange);
    background: rgba(247, 76, 0, 0.15);
    padding: 2px 8px;
    border-radius: 4px;
    min-width: 28px;
    text-align: center;
}

/* Workbook Filter */
.workbook-filter {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 40px;
}

.filter-btn {
    padding: 10px 20px;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 50px;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--rust-orange);
    color: var(--rust-orange);
}

.filter-btn.active {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
}

/* Workbook Grid */
.workbook-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 20px;
}

.project-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 24px;
    position: relative;
    transition: all 0.3s ease;
}

.project-card:hover {
    transform: translateY(-4px);
    border-color: rgba(247, 76, 0, 0.4);
    box-shadow: var(--shadow-lg), 0 0 30px rgba(247, 76, 0, 0.1);
}

.project-num {
    position: absolute;
    top: 16px;
    right: 16px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    background: rgba(110, 118, 129, 0.15);
    padding: 4px 10px;
    border-radius: 20px;
}

.project-card h4 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--rust-orange-light);
    font-family: 'JetBrains Mono', monospace;
}

.project-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* CTA Section */
.cta-section {
    text-align: center;
    background: linear-gradient(135deg, rgba(247, 76, 0, 0.1) 0%, transparent 50%);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.cta-section h2 {
    font-size: 2rem;
    margin-bottom: 16px;
}

.cta-section p {
    color: var(--text-secondary);
    margin-bottom: 32px;
    font-size: 1.125rem;
}

/* Footer */
.footer {
    background: var(--bg-darker);
    padding: 60px 0 30px;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 40px;
    margin-bottom: 40px;
}

.footer-brand h3 {
    font-size: 1.25rem;
    margin-bottom: 8px;
}

.footer-brand p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

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

.footer-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: var(--rust-orange);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid var(--border-color);
}

.footer-bottom p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav {
        flex-direction: column;
        gap: 16px;
        padding: 16px 24px;
    }

    .nav-links {
        gap: 20px;
    }

    .hero-layout {
        flex-direction: column;
        padding: 100px 16px 60px;
        gap: 40px;
    }

    .hero-content {
        max-width: 100%;
    }

    .hero h1 {
        font-size: 2.5rem;
    }

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

    .hero-stats {
        gap: 30px;
    }

    .stat-number {
        font-size: 2rem;
    }

    .section {
        padding: 60px 0;
    }

    .section-title {
        font-size: 1.75rem;
    }

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

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

    .footer-content {
        flex-direction: column;
        text-align: center;
    }

    .footer-links {
        justify-content: center;
    }
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.chapter-category,
.project-card {
    animation: fadeInUp 0.5s ease forwards;
    opacity: 0;
}

.chapter-category:nth-child(1) { animation-delay: 0.1s; }
.chapter-category:nth-child(2) { animation-delay: 0.15s; }
.chapter-category:nth-child(3) { animation-delay: 0.2s; }
.chapter-category:nth-child(4) { animation-delay: 0.25s; }
.chapter-category:nth-child(5) { animation-delay: 0.3s; }
.chapter-category:nth-child(6) { animation-delay: 0.35s; }
.chapter-category:nth-child(7) { animation-delay: 0.4s; }
.chapter-category:nth-child(8) { animation-delay: 0.45s; }
.chapter-category:nth-child(9) { animation-delay: 0.5s; }

.project-card {
    animation-delay: 0.05s;
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 10px;
}

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

::-webkit-scrollbar-thumb {
    background: var(--border-color);
    border-radius: 5px;
}

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

/* Selection */
::selection {
    background: rgba(247, 76, 0, 0.3);
    color: var(--text-primary);
}

/* ============================================
   PRICING SECTION
   ============================================ */
.pricing-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 2rem;
    max-width: 1100px;
    margin: 0 auto;
}

.pricing-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    position: relative;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.pricing-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.3);
}

.pricing-card-featured {
    border-color: var(--accent);
    background: linear-gradient(135deg, var(--bg-card) 0%, rgba(247, 76, 0, 0.05) 100%);
}

.pricing-badge {
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--accent);
    color: white;
    padding: 0.35rem 1rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.pricing-tier {
    font-size: 1.35rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 1rem;
    text-align: center;
}

.pricing-price {
    text-align: center;
    margin-bottom: 1.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.price-amount {
    font-size: 3rem;
    font-weight: 700;
    color: var(--text-primary);
}

.pricing-features {
    list-style: none;
    padding: 0;
    margin: 0 0 1.5rem 0;
    flex: 1;
}

.pricing-features li {
    padding: 0.6rem 0;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.pricing-features li::before {
    content: "✓";
    color: var(--success);
    font-weight: bold;
}

/* ============================================
   PAYMENT BUTTONS
   ============================================ */
.payment-buttons {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
    margin-top: auto;
}

.paypal-button-container {
    min-height: 40px;
}

.pay-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    width: 100%;
    padding: 0.75rem 1rem;
    border: none;
    border-radius: 6px;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.pay-icon {
    width: 20px;
    height: 20px;
}

.pay-btn-card {
    background: linear-gradient(135deg, #1a1f36 0%, #2d3748 100%);
    color: white;
    border: 1px solid #4a5568;
}

.pay-btn-card:hover {
    background: linear-gradient(135deg, #2d3748 0%, #4a5568 100%);
    transform: translateY(-1px);
}

.pay-btn-ideal {
    background: linear-gradient(135deg, #cc0066 0%, #e91e8c 100%);
    color: white;
}

.pay-btn-ideal:hover {
    background: linear-gradient(135deg, #e91e8c 0%, #ff4da6 100%);
    transform: translateY(-1px);
}

/* ============================================
   RESPONSIVE PRICING
   ============================================ */
@media (max-width: 900px) {
    .pricing-grid {
        grid-template-columns: 1fr;
        max-width: 400px;
    }

    .pricing-card-featured {
        order: -1;
    }
}

@media (max-width: 480px) {
    .pricing-card {
        padding: 1.5rem;
    }

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