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

:root {
    --primary-color: #f7931a;
    --primary-dark: #e87b0f;
    --primary-light: #ffb347;
    --secondary-color: #2c3e50;
    --background-color: #ffffff;
    --background-alt: #f8f9fa;
    --text-color: #2d3748;
    --text-light: #718096;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.2);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    position: relative;
    overflow-x: hidden;
}

.background-pattern {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    opacity: 0.03;
    background-image:
        linear-gradient(30deg, #f7931a 12%, transparent 12.5%, transparent 87%, #f7931a 87.5%, #f7931a),
        linear-gradient(150deg, #f7931a 12%, transparent 12.5%, transparent 87%, #f7931a 87.5%, #f7931a),
        linear-gradient(30deg, #f7931a 12%, transparent 12.5%, transparent 87%, #f7931a 87.5%, #f7931a),
        linear-gradient(150deg, #f7931a 12%, transparent 12.5%, transparent 87%, #f7931a 87.5%, #f7931a);
    background-size: 80px 140px;
    background-position: 0 0, 0 0, 40px 70px, 40px 70px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Navbar */
.navbar {
    position: sticky;
    top: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
    padding: 16px 0;
    transition: all 0.3s ease;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 600;
    font-size: 1.1rem;
    color: var(--text-color);
}

.logo svg {
    transition: transform 0.3s ease;
}

.logo:hover svg {
    transform: rotate(360deg);
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    font-size: 0.95rem;
    transition: color 0.3s ease;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}

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

.nav-link:hover::after {
    width: 100%;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f7931a 100%);
    color: white;
    padding: 120px 24px 100px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><defs><pattern id="grid" width="100" height="100" patternUnits="userSpaceOnUse"><path d="M 100 0 L 0 0 0 100" fill="none" stroke="white" stroke-width="0.5" opacity="0.1"/></pattern></defs><rect width="100" height="100" fill="url(%23grid)"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-block;
    padding: 8px 20px;
    background: rgba(255, 255, 255, 0.2);
    backdrop-filter: blur(10px);
    border-radius: 50px;
    font-size: 0.85rem;
    font-weight: 500;
    letter-spacing: 0.5px;
    margin-bottom: 24px;
    border: 1px solid rgba(255, 255, 255, 0.3);
    animation: fadeInDown 0.8s ease;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 24px;
    line-height: 1.2;
    text-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-author {
    font-size: 1.3rem;
    margin-bottom: 8px;
    opacity: 0.95;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.highlight {
    background: linear-gradient(120deg, rgba(255, 255, 255, 0.3) 0%, rgba(255, 255, 255, 0.1) 100%);
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: 600;
}

.hero-date {
    font-size: 1.1rem;
    opacity: 0.9;
    margin-bottom: 40px;
    animation: fadeInUp 0.8s ease 0.6s both;
}

.hero-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    animation: fadeInUp 0.8s ease 0.8s both;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 32px;
    text-decoration: none;
    border-radius: 8px;
    font-weight: 600;
    font-size: 1rem;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
}

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

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

.btn-secondary {
    background-color: rgba(255, 255, 255, 0.2);
    color: white;
    border: 2px solid rgba(255, 255, 255, 0.5);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background-color: rgba(255, 255, 255, 0.3);
    border-color: white;
    transform: translateY(-2px);
}

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

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

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

.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-label {
    display: inline-block;
    font-size: 0.85rem;
    font-weight: 600;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    color: var(--primary-color);
    margin-bottom: 12px;
}

.section-header h2 {
    font-size: 2.8rem;
    font-weight: 700;
    color: var(--secondary-color);
    border: none;
    padding: 0;
    margin: 0;
}

/* Intro Section */
.intro-section {
    background-color: var(--background-color);
}

.intro-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 60px;
    align-items: center;
}

.intro-text .lead {
    font-size: 1.25rem;
    line-height: 1.8;
    color: var(--text-color);
    font-weight: 500;
    margin-bottom: 20px;
}

.intro-text p {
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-light);
}

.intro-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.stat-card {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
    padding: 30px 20px;
    border-radius: 12px;
    text-align: center;
    color: white;
    box-shadow: var(--shadow-md);
    transition: transform 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-5px);
}

.stat-number {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.stat-label {
    font-size: 0.9rem;
    opacity: 0.95;
    font-weight: 500;
}

/* History Section */
.history-section {
    background: linear-gradient(to bottom, var(--background-color) 0%, var(--background-alt) 100%);
    padding: 100px 0;
}

.history-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: start;
    margin-top: 40px;
}

.history-text h3 {
    font-size: 2rem;
    color: var(--secondary-color);
    margin-bottom: 24px;
    font-weight: 600;
}

.history-lead {
    font-size: 1.3rem;
    line-height: 1.7;
    color: var(--primary-color);
    font-weight: 600;
    margin-bottom: 24px;
    padding-left: 20px;
    border-left: 4px solid var(--primary-color);
}

.history-text p {
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-color);
    margin-bottom: 20px;
}

.ford-quote {
    background: linear-gradient(135deg, rgba(247, 147, 26, 0.05) 0%, rgba(247, 147, 26, 0.1) 100%);
    padding: 30px;
    border-left: 4px solid var(--primary-color);
    margin: 32px 0;
    font-style: italic;
    border-radius: 8px;
}

.ford-quote::before {
    content: '"';
    font-size: 4rem;
    color: var(--primary-color);
    opacity: 0.3;
    font-family: Georgia, serif;
    line-height: 0;
    display: block;
    margin-bottom: 20px;
}

.ford-quote cite {
    display: block;
    font-style: normal;
    font-weight: 600;
    color: var(--secondary-color);
    margin-top: 16px;
    font-size: 0.95rem;
}

.history-connection {
    background-color: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    margin-top: 32px;
    border: 1px solid var(--border-color);
}

.history-connection h4 {
    font-size: 1.3rem;
    color: var(--secondary-color);
    margin-bottom: 16px;
    font-weight: 600;
}

.history-connection p {
    margin-bottom: 0;
}

.history-image {
    position: sticky;
    top: 100px;
}

.image-wrapper {
    background-color: white;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
    margin-bottom: 30px;
}

.image-wrapper img {
    width: 100%;
    height: auto;
    display: block;
    transition: transform 0.3s ease;
}

.image-wrapper:hover img {
    transform: scale(1.02);
}

.image-caption {
    padding: 20px;
    background-color: var(--background-alt);
    border-top: 1px solid var(--border-color);
}

.image-caption p {
    font-size: 0.95rem;
    color: var(--text-color);
    margin: 0;
    line-height: 1.6;
}

.image-caption p:first-child {
    color: var(--secondary-color);
    margin-bottom: 4px;
}

.source-link {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 1px solid var(--border-color);
}

.source-link a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: color 0.3s ease;
}

.source-link a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.image-wrapper a {
    display: block;
    cursor: pointer;
}

.image-wrapper a img {
    cursor: zoom-in;
}

.timeline {
    background-color: white;
    border-radius: 12px;
    padding: 24px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
}

.timeline-item {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 16px 0;
    border-bottom: 1px solid var(--border-color);
}

.timeline-item:last-child {
    border-bottom: none;
    padding-bottom: 0;
}

.timeline-item:first-child {
    padding-top: 0;
}

.timeline-year {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    font-family: 'Fira Code', monospace;
    min-width: 80px;
}

.timeline-desc {
    font-size: 1rem;
    color: var(--text-color);
    font-weight: 500;
}

/* PDF Section */
.pdf-section {
    background-color: var(--background-alt);
}

.pdf-wrapper {
    background-color: white;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

.pdf-toolbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 24px;
    background-color: var(--background-alt);
    border-bottom: 1px solid var(--border-color);
}

.pdf-info {
    display: flex;
    align-items: center;
    gap: 12px;
}

.pdf-info svg {
    color: var(--text-color);
    stroke-width: 2;
}

.pdf-filename {
    font-weight: 600;
    color: var(--text-color);
    font-family: 'Fira Code', monospace;
}

.pdf-size {
    font-size: 0.85rem;
    color: var(--text-light);
    padding: 4px 10px;
    background-color: white;
    border-radius: 4px;
}

.pdf-actions {
    display: flex;
    gap: 8px;
}

.tool-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: 8px;
    background-color: white;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    transition: all 0.3s ease;
    text-decoration: none;
}

.tool-btn:hover {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
}

.pdf-viewer-container {
    position: relative;
    background-color: #525659;
}

.pdf-iframe {
    display: block;
    border: none;
}

.pdf-fallback {
    text-align: center;
    padding: 20px;
    background-color: var(--background-alt);
    border-top: 1px solid var(--border-color);
}

.pdf-fallback a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 600;
}

.pdf-fallback a:hover {
    text-decoration: underline;
}

/* Concepts Section */
.concepts-section {
    background-color: var(--background-color);
}

.concepts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}

.concept-card {
    background-color: white;
    padding: 32px;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
}

.concept-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary-color);
}

.concept-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    opacity: 0.3;
    margin-bottom: 16px;
    font-family: 'Fira Code', monospace;
}

.concept-card h3 {
    font-size: 1.4rem;
    color: var(--secondary-color);
    margin-bottom: 12px;
    font-weight: 600;
}

.concept-card p {
    color: var(--text-light);
    line-height: 1.7;
    flex-grow: 1;
    margin-bottom: 16px;
}

.concept-footer {
    margin-top: auto;
}

.concept-tag {
    display: inline-block;
    padding: 6px 12px;
    background-color: rgba(247, 147, 26, 0.1);
    color: var(--primary-color);
    border-radius: 6px;
    font-size: 0.8rem;
    font-weight: 600;
}

/* Quote Section */
.quote-section {
    background: linear-gradient(135deg, var(--secondary-color) 0%, #34495e 100%);
    padding: 80px 24px;
}

.bitcoin-quote {
    max-width: 900px;
    margin: 0 auto;
    text-align: center;
}

.bitcoin-quote p {
    font-size: 1.6rem;
    line-height: 1.8;
    color: white;
    font-weight: 400;
    font-style: italic;
    margin-bottom: 24px;
    position: relative;
}

.bitcoin-quote p::before {
    content: '"';
    font-size: 4rem;
    color: var(--primary-color);
    position: absolute;
    top: -20px;
    left: -40px;
    font-family: Georgia, serif;
}

.bitcoin-quote cite {
    display: block;
    font-size: 1.1rem;
    color: rgba(255, 255, 255, 0.8);
    font-style: normal;
    font-weight: 500;
}

/* Footer */
footer {
    background-color: var(--secondary-color);
    color: white;
    padding: 60px 24px 30px;
}

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

.footer-info h3 {
    font-size: 1.5rem;
    margin-bottom: 12px;
}

.footer-info p {
    color: rgba(255, 255, 255, 0.8);
    line-height: 1.6;
}

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

.footer-links a {
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-bottom p {
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .intro-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .intro-stats {
        max-width: 500px;
        margin: 0 auto;
    }

    .concepts-grid {
        grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    }

    .history-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .history-image {
        position: static;
    }
}

@media (max-width: 768px) {
    .nav-links {
        gap: 20px;
    }

    .nav-link {
        font-size: 0.9rem;
    }

    .hero {
        padding: 80px 24px 60px;
    }

    .hero-title {
        font-size: 2.2rem;
    }

    .section-header h2 {
        font-size: 2rem;
    }

    .pdf-toolbar {
        flex-direction: column;
        gap: 16px;
        align-items: flex-start;
    }

    .pdf-iframe {
        height: 600px;
    }

    .footer-content {
        flex-direction: column;
    }

    .bitcoin-quote p {
        font-size: 1.3rem;
    }

    .bitcoin-quote p::before {
        font-size: 3rem;
        left: -20px;
    }

    .history-section {
        padding: 60px 0;
    }

    .history-text h3 {
        font-size: 1.6rem;
    }

    .history-lead {
        font-size: 1.15rem;
    }

    .ford-quote {
        padding: 20px;
    }

    .ford-quote::before {
        font-size: 3rem;
    }

    .timeline-year {
        font-size: 1.2rem;
        min-width: 60px;
    }
}

@media (max-width: 640px) {
    .hero-actions {
        flex-direction: column;
        width: 100%;
    }

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

    .intro-stats {
        grid-template-columns: 1fr;
    }

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

    .nav-links {
        display: none;
    }
}

/* Language Toggle */
.lang-toggle {
    display: flex;
    gap: 6px;
    margin-left: 24px;
    padding-left: 24px;
    border-left: 1px solid var(--border-color);
}

.lang-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 6px 14px;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.85rem;
    transition: all 0.3s ease;
    font-family: 'Fira Code', monospace;
}

.lang-btn:hover {
    background-color: var(--background-alt);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.lang-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

@media (max-width: 768px) {
    .lang-toggle {
        margin-left: 16px;
        padding-left: 16px;
    }

    .lang-btn {
        padding: 4px 10px;
        font-size: 0.8rem;
    }
}

@media (max-width: 640px) {
    .nav-container {
        flex-wrap: wrap;
    }

    .lang-toggle {
        margin-left: 0;
        padding-left: 0;
        border-left: none;
        margin-top: 12px;
        width: 100%;
        justify-content: center;
    }
}