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

:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #2c3e50;
    --text-light: #7f8c8d;
    --background-color: #ffffff;
    --surface-color: #f8f9fa;
    --border-color: #e9ecef;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 4px 20px rgba(0, 0, 0, 0.15);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    font-size: 16px;
}

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

/* Header Styles */
.header {
    background: var(--background-color);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-banner {
    text-align: center;
    padding: 20px 0;
}

.banner-image {
    max-width: 100%;
    height: auto;
    max-height: 150px;
    object-fit: contain;
}

.nav {
    border-top: 2px solid var(--secondary-color);
    padding: 0;
}

.nav-list {
    display: flex;
    justify-content: center;
    list-style: none;
    margin: 0;
    padding: 0;
    flex-wrap: wrap;
}

.nav-list li {
    margin: 0;
}

.nav-link {
    display: block;
    padding: 15px 25px;
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    border-bottom: 3px solid transparent;
}

.nav-link:hover,
.nav-link.active {
    color: var(--secondary-color);
    border-bottom-color: var(--secondary-color);
    background-color: rgba(52, 152, 219, 0.05);
}

/* Main Content */
.main {
    padding: 40px 0;
}

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, var(--surface-color) 0%, var(--background-color) 100%);
    border-radius: var(--border-radius);
    padding: 40px;
    margin-bottom: 40px;
    box-shadow: var(--shadow);
}

.hero-content {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 40px;
    align-items: start;
}

.author-image {
    width: 100%;
    height: auto;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

.hero-text p {
    margin-bottom: 20px;
    font-size: 16px;
    line-height: 1.7;
}

.hero-text em {
    font-style: italic;
    color: var(--accent-color);
    font-weight: 500;
}

.signature {
    margin-top: 30px;
}

.signature-image {
    max-width: 150px;
    height: auto;
}

/* Book Info Section */
.book-info {
    margin-bottom: 40px;
}

.book-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 40px;
    background: var(--background-color);
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow);
}

/* Social Links */
.social-links {
    display: flex;
    gap: 15px;
    margin-bottom: 30px;
    flex-wrap: wrap;
}

.social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 20px;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.social-link.twitter {
    background: #1da1f2;
    color: white;
}

.social-link.facebook {
    background: #4267b2;
    color: white;
}

.social-link:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

/* Order Button */
.order-button {
    display: inline-block;
    background: linear-gradient(135deg, var(--secondary-color), #2980b9);
    color: white;
    padding: 15px 30px;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    font-size: 18px;
    transition: var(--transition);
    box-shadow: var(--shadow);
    margin: 20px 0;
}

.order-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    background: linear-gradient(135deg, #2980b9, var(--secondary-color));
}

/* Warning Boxes */
.warning {
    background: #fef9e7;
    border: 1px solid #f39c12;
    border-radius: var(--border-radius);
    padding: 20px;
    margin: 20px 0;
}

.warning strong {
    color: var(--accent-color);
}

.warning-extended {
    background: #fff5f5;
    border: 1px solid var(--accent-color);
    border-radius: var(--border-radius);
    padding: 20px;
    margin: 20px 0;
}

/* Book Details */
.book-details p {
    margin-bottom: 20px;
    line-height: 1.7;
}

.scholarship-info {
    background: var(--surface-color);
    padding: 30px;
    border-radius: var(--border-radius);
    margin: 30px 0;
}

.scholarship-categories {
    margin: 20px 0;
}

.scholarship-category {
    margin-bottom: 25px;
}

.scholarship-category h3 {
    color: var(--secondary-color);
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 8px;
}

.dedication {
    font-style: italic;
    font-weight: 500;
    color: var(--accent-color);
    text-align: center;
    margin-top: 20px;
}

.portrait {
    text-align: center;
    margin-top: 30px;
}

.portrait-image {
    max-width: 300px;
    width: 100%;
    height: auto;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

/* Version Info Section */
.version-info {
    background: var(--surface-color);
    border-radius: var(--border-radius);
    padding: 40px;
    box-shadow: var(--shadow);
}

.version-content h2 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: 28px;
    font-weight: 600;
}

.version-content p {
    margin-bottom: 20px;
    line-height: 1.7;
}

/* Footer */
.footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 30px 0;
    margin-top: 60px;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
    
    .hero-content {
        grid-template-columns: 1fr;
        gap: 30px;
        text-align: center;
    }
    
    .hero-section {
        padding: 30px 20px;
    }
    
    .book-content {
        grid-template-columns: 1fr;
        gap: 30px;
        padding: 30px 20px;
    }
    
    .nav-list {
        flex-direction: column;
    }
    
    .nav-link {
        text-align: center;
        border-bottom: none;
        border-left: 3px solid transparent;
    }
    
    .nav-link:hover,
    .nav-link.active {
        border-left-color: var(--secondary-color);
        border-bottom-color: transparent;
    }
    
    .social-links {
        justify-content: center;
    }
    
    .book-subtitle {
        text-align: center;
    }
    
    .order-button {
        display: block;
        text-align: center;
        margin: 20px auto;
    }
}

@media (max-width: 480px) {
    .hero-section,
    .book-content,
    .version-info {
        padding: 20px 15px;
    }
    
    .banner-image {
        max-height: 100px;
    }
    
    .nav-link {
        padding: 12px 15px;
        font-size: 14px;
    }
    
    .order-button {
        font-size: 16px;
        padding: 12px 25px;
    }
    
    .version-content h2 {
        font-size: 24px;
    }
}

/* Animations */
.animate-on-scroll {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* Keyboard navigation styles */
.keyboard-navigation *:focus {
    outline: 2px solid var(--secondary-color);
    outline-offset: 2px;
}

/* Loading states */
.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin: -10px 0 0 -10px;
    border: 2px solid transparent;
    border-top: 2px solid var(--secondary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

/* Skip link for accessibility */
.skip-link {
    position: absolute;
    top: -40px;
    left: 6px;
    background: var(--primary-color);
    color: white;
    padding: 8px;
    z-index: 1000;
    text-decoration: none;
    border-radius: 0 0 4px 4px;
}

.skip-link:focus {
    top: 0;
}

/* External link indicators */
.external-icon {
    font-size: 0.8em;
    opacity: 0.7;
}

/* Print Styles */
@media print {
    .header,
    .footer,
    .social-links,
    .order-button {
        display: none;
    }
    
    .main {
        padding: 0;
    }
    
    .hero-section,
    .book-content,
    .version-info {
        box-shadow: none;
        border: 1px solid #ccc;
    }
    
    a[href^="http"]:after {
        content: " (" attr(href) ")";
        font-size: 0.8em;
        color: #666;
    }
}