:root {
    --primary-color: #2563eb;
    --secondary-color: #1e40af;
    --accent-color: #ef4444;
    --text-dark: #1f2937;
    --text-light: #6b7280;
    --bg-light: #f9fafb;
    --bg-white: #ffffff;
    --border-color: #e5e7eb;
    --oreilly-red: #C1272D;
    --pearson-blue: #003057;
}

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

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

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

/* Navigation */
.main-nav {
    background: var(--bg-white);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-dark);
    text-decoration: none;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-menu a {
    color: var(--text-dark);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-menu a:hover,
.nav-menu a.active {
    color: var(--primary-color);
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-white) 100%);
    padding: 6rem 20px 4rem;
    text-align: center;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.tagline {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 2rem;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: 6px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s;
    display: inline-block;
}

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

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

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

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

/* Books Section */
.books-section {
    padding: 4rem 0;
    background: var(--bg-white);
}

.books-section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.book-card {
    background: var(--bg-white);
    border-radius: 12px;
    padding: 2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s, box-shadow 0.3s;
}

.book-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.15);
}

.book-publisher {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: white;
}

.book-card:nth-child(1) .book-publisher {
    background: var(--oreilly-red);
}

.book-card:nth-child(2) .book-publisher {
    background: var(--pearson-blue);
}

.book-cover {
    width: 200px;
    height: auto;
    margin: 1rem auto;
    display: block;
    border-radius: 4px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
}

.book-card h3 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-dark);
}

.book-subtitle {
    color: var(--text-light);
    font-style: italic;
    margin-bottom: 1rem;
}

.book-description {
    color: var(--text-dark);
    margin-bottom: 1.5rem;
    line-height: 1.7;
}

.book-testimonial {
    background: var(--bg-light);
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 1.5rem;
    border-left: 4px solid var(--primary-color);
}

.book-testimonial p {
    font-style: italic;
    color: var(--text-dark);
}

.book-links {
    display: flex;
    gap: 1rem;
}

.btn-small {
    padding: 0.5rem 1rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 4px;
    font-size: 0.875rem;
    transition: background 0.3s;
}

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

/* Expertise Section */
.expertise-section {
    padding: 4rem 0;
    background: var(--bg-light);
}

.expertise-section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.expertise-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.expertise-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 8px;
    text-align: center;
    transition: transform 0.3s;
}

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

.expertise-card h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.expertise-card p {
    color: var(--text-dark);
    line-height: 1.6;
}

/* Featured Project Section */
.featured-project-section {
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-white) 100%);
}

.featured-project-section h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--text-dark);
}

.project-card-featured {
    background: var(--bg-white);
    border-radius: 12px;
    padding: 3rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    max-width: 900px;
    margin: 0 auto;
    border: 1px solid var(--border-color);
    transition: box-shadow 0.3s;
}

.project-card-featured:hover {
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.15);
}

.project-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.project-header h3 {
    font-size: 2rem;
    color: var(--text-dark);
    margin: 0;
    flex: 1;
    min-width: 250px;
}

.project-badge {
    display: inline-block;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.project-badge.live {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
    color: white;
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
}

.project-description {
    font-size: 1.125rem;
    color: var(--text-dark);
    line-height: 1.8;
    margin-bottom: 2rem;
}

.project-highlights {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 8px;
    margin-bottom: 2rem;
    border-left: 4px solid var(--primary-color);
}

.project-highlights h4 {
    font-size: 1.125rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.project-highlights ul {
    list-style: none;
    padding-left: 0;
}

.project-highlights li {
    padding: 0.5rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-dark);
    line-height: 1.6;
}

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

.project-tech {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.project-tech strong {
    color: var(--text-dark);
    font-size: 1rem;
}

.tech-tag {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.4rem 0.9rem;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    transition: transform 0.2s, background 0.2s;
}

.tech-tag:hover {
    transform: translateY(-2px);
    background: var(--secondary-color);
}

.project-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.project-links .btn {
    flex: 1;
    min-width: 200px;
    text-align: center;
}

/* Footer */
footer {
    background: var(--text-dark);
    color: white;
    padding: 2rem 0;
    margin-top: 4rem;
}

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

.social-links {
    display: flex;
    gap: 1.5rem;
}

.social-links a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.social-links a:hover {
    opacity: 0.8;
}

/* Responsive Design */
@media (max-width: 768px) {
    .hero-content h1 {
        font-size: 2rem;
    }

    .tagline {
        font-size: 1rem;
    }

    .cta-buttons {
        flex-direction: column;
        align-items: center;
    }

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

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

    .nav-menu {
        gap: 1rem;
        font-size: 0.9rem;
    }

    footer .container {
        flex-direction: column;
        text-align: center;
        gap: 1rem;
    }

    .book-cover {
        width: 150px;
    }

    .project-card-featured {
        padding: 2rem 1.5rem;
    }

    .project-header {
        flex-direction: column;
        align-items: flex-start;
    }

    .project-header h3 {
        font-size: 1.5rem;
    }

    .project-highlights {
        padding: 1.5rem;
    }

    .project-links {
        flex-direction: column;
    }

    .project-links .btn {
        min-width: 100%;
    }
}