/* CSS Variables for Professional Theme */
:root {
    --primary: #2c3e50;
    --secondary: #3498db;
    --accent: #9b59b6;
    --success: #27ae60;
    --warning: #f39c12;
    --danger: #e74c3c;
    --light: #ecf0f1;
    --dark: #2c3e50;
    --text: #2c3e50;
    --text-light: #7f8c8d;
    --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 20px 40px rgba(0, 0, 0, 0.15);
    --transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    --border-radius: 12px;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.7;
    color: var(--text);
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

.container {
    width: 90%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Professional Header Styles */
.top-bar {
    background: var(--primary);
    color: white;
    padding: 12px 0;
    font-size: 0.9rem;
    border-bottom: 3px solid var(--accent);
}

.top-bar-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.social-icons {
    display: flex;
    gap: 15px;
}

.social-icons a {
    color: white;
    font-size: 1.1rem;
    transition: var(--transition);
    width: 35px;
    height: 35px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.1);
}

.social-icons a:hover {
    background: var(--secondary);
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(52, 152, 219, 0.4);
}

.contact-info {
    display: flex;
    gap: 25px;
    flex-wrap: wrap;
}

.contact-info span {
    display: flex;
    align-items: center;
    gap: 8px;
    font-weight: 500;
}

.contact-info i {
    color: var(--accent);
}

/* Enhanced Navigation */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    gap: 12px;
}

.logo-icon {
    font-size: 2.2rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
}

.logo h1 {
    font-size: 2rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-links li {
    position: relative;
}

.nav-links a {
    text-decoration: none;
    color: var(--text);
    font-weight: 600;
    font-size: 0.95rem;
    transition: var(--transition);
    padding: 8px 16px;
    border-radius: 25px;
    position: relative;
}

.nav-links a:hover {
    color: var(--secondary);
    background: rgba(52, 152, 219, 0.1);
}

.nav-links a.active {
    color: var(--secondary);
    background: rgba(52, 152, 219, 0.1);
}

.search-bar {
    display: flex;
    align-items: center;
    background: white;
    border-radius: 25px;
    padding: 8px 20px;
    width: 300px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
    border: 2px solid transparent;
}

.search-bar:focus-within {
    border-color: var(--secondary);
    box-shadow: 0 5px 20px rgba(52, 152, 219, 0.2);
    transform: translateY(-2px);
}

.search-bar input {
    border: none;
    background: transparent;
    outline: none;
    width: 100%;
    padding: 0 12px;
    font-size: 0.9rem;
}

.search-bar button {
    background: none;
    border: none;
    color: var(--text-light);
    cursor: pointer;
    transition: var(--transition);
}

.search-bar button:hover {
    color: var(--secondary);
    transform: scale(1.1);
}

/* Enhanced Hero Slider */
.hero-slider {
    position: relative;
    height: 700px;
    overflow: hidden;
    border-radius: var(--border-radius);
    margin: 40px 0;
    box-shadow: var(--shadow);
}

.slide {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    transition: opacity 1s ease, transform 1s ease;
    display: flex;
    align-items: center;
    padding: 0 80px;
    background-size: cover;
    background-position: center;
    transform: scale(1.1);
}

.slide.active {
    opacity: 1;
    transform: scale(1);
}

.slide::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(44, 62, 80, 0.8) 0%, rgba(52, 152, 219, 0.6) 100%);
}

.slide-content {
    position: relative;
    max-width: 600px;
    color: white;
    z-index: 2;
}

.slide-content h2 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 25px;
    line-height: 1.2;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 1s ease;
}

.slide-content p {
    font-size: 1.3rem;
    margin-bottom: 35px;
    text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
    animation: fadeInUp 1s ease 0.2s both;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 15px 35px;
    background: var(--gradient-secondary);
    color: white;
    border: none;
    border-radius: 50px;
    font-weight: 700;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    box-shadow: var(--shadow);
    font-size: 1rem;
    position: relative;
    overflow: hidden;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    transition: left 0.5s;
}

.btn:hover::before {
    left: 100%;
}

.btn:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-hover);
}

.btn-outline {
    background: transparent;
    border: 2px solid white;
    color: white;
}

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

.slider-controls {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    gap: 10px;
    z-index: 3;
}

.slider-dot {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.5);
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid transparent;
}

.slider-dot.active {
    background: white;
    transform: scale(1.3);
    border-color: var(--accent);
}

.slider-arrow {
    position: absolute;
    top: 50%;
    transform: translateY(-50%);
    background: rgba(255, 255, 255, 0.2);
    color: white;
    width: 60px;
    height: 60px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    backdrop-filter: blur(10px);
    border: 2px solid rgba(255, 255, 255, 0.3);
    z-index: 3;
}

.slider-arrow:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-50%) scale(1.1);
}

.slider-arrow.prev {
    left: 30px;
}

.slider-arrow.next {
    right: 30px;
}

/* Enhanced Features Section */
.section-title {
    text-align: center;
    margin: 80px 0 50px;
}

.section-title h2 {
    font-size: 3rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 20px;
    position: relative;
    display: inline-block;
}

.section-title h2::after {
    content: '';
    position: absolute;
    bottom: -15px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 4px;
    background: var(--gradient-accent);
    border-radius: 2px;
}

.section-title p {
    color: var(--text-light);
    max-width: 700px;
    margin: 0 auto;
    font-size: 1.2rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 40px;
    margin-bottom: 80px;
}

.feature-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 40px 30px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    text-align: center;
    position: relative;
    overflow: hidden;
}

.feature-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-primary);
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-hover);
}

.feature-icon {
    font-size: 3.5rem;
    margin-bottom: 25px;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    display: inline-block;
}

.feature-card h3 {
    font-size: 1.6rem;
    margin-bottom: 15px;
    color: var(--primary);
}

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

/* Enhanced Science Facts */
.science-fact {
    background: white;
    border-radius: var(--border-radius);
    padding: 50px;
    box-shadow: var(--shadow);
    margin-bottom: 80px;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.science-fact::before {
    content: '🔬';
    position: absolute;
    top: -30px;
    right: -30px;
    font-size: 8rem;
    opacity: 0.1;
    transform: rotate(15deg);
}

.fact-content {
    font-size: 1.4rem;
    font-style: italic;
    margin-bottom: 30px;
    color: var(--primary);
    line-height: 1.6;
    position: relative;
    z-index: 2;
}

.new-fact-btn {
    background: var(--gradient-accent);
    border: none;
}

/* Enhanced Footer */
footer {
    background: var(--primary);
    color: white;
    padding: 80px 0 30px;
    margin-top: 100px;
    position: relative;
}

footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--gradient-accent);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 50px;
    margin-bottom: 50px;
}

.footer-column h3 {
    font-size: 1.4rem;
    margin-bottom: 25px;
    position: relative;
    padding-bottom: 15px;
}

.footer-column h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--accent);
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 12px;
}

.footer-links a {
    color: #bdc3c7;
    text-decoration: none;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 10px;
}

.footer-links a:hover {
    color: white;
    padding-left: 10px;
}

.footer-links a i {
    width: 20px;
    text-align: center;
}

.copyright {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: #bdc3c7;
    font-size: 0.9rem;
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
    100% {
        transform: scale(1);
    }
}

/* Enhanced Responsive Design */
@media (max-width: 1200px) {
    .slide-content h2 {
        font-size: 3rem;
    }
    
    .hero-slider {
        height: 600px;
    }
}

@media (max-width: 992px) {
    .nav-links {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .slide {
        padding: 0 40px;
    }
    
    .slide-content h2 {
        font-size: 2.5rem;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
        gap: 30px;
    }
}

@media (max-width: 768px) {
    .top-bar-content {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
    
    .contact-info {
        justify-content: center;
    }
    
    .search-bar {
        width: 100%;
        max-width: 400px;
        margin: 0 auto;
    }
    
    .slide {
        padding: 0 30px;
    }
    
    .slide-content h2 {
        font-size: 2rem;
    }
    
    .slide-content p {
        font-size: 1.1rem;
    }
    
    .hero-slider {
        height: 500px;
        margin: 20px 0;
    }
    
    .slider-arrow {
        width: 50px;
        height: 50px;
        font-size: 1.2rem;
    }
    
    .section-title h2 {
        font-size: 2.2rem;
    }
    
    .science-fact {
        padding: 30px 20px;
    }
    
    .fact-content {
        font-size: 1.2rem;
    }
}

@media (max-width: 576px) {
    .container {
        width: 95%;
        padding: 0 15px;
    }
    
    .slide-content h2 {
        font-size: 1.8rem;
    }
    
    .btn {
        padding: 12px 25px;
        font-size: 0.9rem;
    }
    
    .hero-slider {
        height: 450px;
    }
    
    .section-title h2 {
        font-size: 2rem;
    }
    
    .feature-card {
        padding: 30px 20px;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }
}

/* Mobile Menu */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--primary);
    cursor: pointer;
    padding: 5px;
}

.mobile-menu {
    position: fixed;
    top: 0;
    left: -100%;
    width: 300px;
    height: 100vh;
    background: white;
    box-shadow: var(--shadow-hover);
    transition: var(--transition);
    z-index: 2000;
    padding: 80px 30px 30px;
}

.mobile-menu.active {
    left: 0;
}

.mobile-menu .nav-links {
    flex-direction: column;
    gap: 0;
}

.mobile-menu .nav-links a {
    display: block;
    padding: 15px 20px;
    border-bottom: 1px solid var(--light);
    border-radius: 0;
}

.mobile-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    z-index: 1999;
    display: none;
}

.mobile-overlay.active {
    display: block;
}

/* Utility Classes */
.text-gradient {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.bg-gradient {
    background: var(--gradient-primary);
}

.shadow-card {
    box-shadow: var(--shadow);
}

.shadow-card-hover {
    box-shadow: var(--shadow-hover);
}

/* Loading States */
.loading {
    opacity: 0.7;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 30px;
    height: 30px;
    border: 3px solid var(--light);
    border-top: 3px solid var(--secondary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
}
/* ===== TOP BAR ===== */
.top-bar {
    background: #1a237e;
    color: white;
    padding: 10px 0;
    font-size: 0.9rem;
}

.top-bar-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

.social-icons {
    display: flex;
    gap: 15px;
}

.social-icons a {
    color: white;
    font-size: 1rem;
    transition: color 0.3s;
}

.social-icons a:hover {
    color: #bbdefb;
}

.contact-info {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.contact-info span {
    display: flex;
    align-items: center;
    gap: 5px;
}

/* ===== NAVIGATION BAR (NEW STYLE - SAME AS PDF LIBRARY) ===== */
.navbar {
    background: white;
    box-shadow: 0 2px 20px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    padding: 0;
    margin: 0;
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
    max-width: 1200px;
    margin: 0 auto;
    padding-left: 20px;
    padding-right: 20px;
}

/* Logo Styles */
.logo {
    display: flex;
    align-items: center;
    gap: 10px;
    text-decoration: none;
    color: #1a237e;
    transition: transform 0.3s ease;
}

.logo:hover {
    transform: translateY(-2px);
}

.logo-icon {
    font-size: 2rem;
    font-weight: normal;
}

.logo h1 {
    font-size: 1.8rem;
    font-weight: 800;
    background: linear-gradient(135deg, #1a237e, #3949ab);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin: 0;
    padding: 0;
}

/* Navigation Links */
.nav-links {
    display: flex;
    gap: 30px;
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-links a {
    text-decoration: none;
    color: #475569;
    font-weight: 500;
    padding: 8px 0;
    position: relative;
    transition: all 0.3s ease;
    font-size: 1rem;
}

.nav-links a:hover,
.nav-links a.active {
    color: #1a237e;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 3px;
    background: linear-gradient(90deg, #1a237e, #3949ab);
    border-radius: 2px;
    transition: width 0.3s ease;
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

/* Search Bar */
.search-bar {
    display: flex;
    align-items: center;
    background: #f1f5f9;
    border-radius: 8px;
    overflow: hidden;
    border: 2px solid transparent;
    transition: all 0.3s ease;
    min-width: 250px;
}

.search-bar:focus-within {
    border-color: #1a237e;
    box-shadow: 0 0 0 3px rgba(26, 35, 126, 0.1);
}

.search-bar input {
    padding: 10px 15px;
    border: none;
    background: transparent;
    flex: 1;
    outline: none;
    font-size: 0.95rem;
    min-width: 0;
}

.search-bar input::placeholder {
    color: #64748b;
}

.search-bar button {
    padding: 10px 15px;
    background: #1a237e;
    color: white;
    border: none;
    cursor: pointer;
    transition: background 0.3s ease;
    display: flex;
    align-items: center;
    justify-content: center;
}

.search-bar button:hover {
    background: #283593;
}

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: #1a237e;
    cursor: pointer;
    padding: 8px;
    border-radius: 5px;
    transition: all 0.3s ease;
}

.mobile-menu-btn:hover {
    background: #f1f5f9;
    transform: rotate(90deg);
}

/* Mobile Menu */
.mobile-menu {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: white;
    z-index: 2000;
    padding: 100px 20px 40px;
    overflow-y: auto;
    transform: translateX(-100%);
    transition: transform 0.3s ease;
}

.mobile-menu.active {
    display: block;
    transform: translateX(0);
}

.mobile-menu .nav-links {
    flex-direction: column;
    gap: 25px;
    align-items: center;
}

.mobile-menu .nav-links a {
    font-size: 1.2rem;
    padding: 10px 20px;
    border-radius: 8px;
    width: 100%;
    text-align: center;
    transition: all 0.3s ease;
}

.mobile-menu .nav-links a:hover,
.mobile-menu .nav-links a.active {
    background: #eef2ff;
    color: #1a237e;
}

.mobile-menu .nav-links a::after {
    display: none;
}

.mobile-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.5);
    z-index: 1999;
    backdrop-filter: blur(3px);
}

.mobile-overlay.active {
    display: block;
}

/* Responsive Design for Navigation Only */
@media (max-width: 992px) {
    .search-bar {
        min-width: 200px;
    }
    
    .nav-links {
        gap: 20px;
    }
}

@media (max-width: 768px) {
    .nav-links,
    .search-bar {
        display: none;
    }
    
    .mobile-menu-btn {
        display: block;
    }
    
    .nav-container {
        padding: 12px 20px;
    }
    
    .logo h1 {
        font-size: 1.6rem;
    }
    
    .logo-icon {
        font-size: 1.8rem;
    }
}

@media (max-width: 480px) {
    .nav-container {
        padding: 10px 15px;
    }
    
    .logo h1 {
        font-size: 1.4rem;
    }
    
    .logo-icon {
        font-size: 1.6rem;
    }
    
    .mobile-menu {
        padding: 80px 20px 40px;
    }
    
    .mobile-menu .nav-links a {
        font-size: 1.1rem;
        padding: 12px 15px;
    }
    
    .top-bar-content {
        justify-content: center;
    }
    
    .contact-info {
        display: none;
    }
}