:root {
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-dark);
    background: #f8f9fa;
    margin: 0;
    padding-bottom: 70px;
}

/* Navbar */
.navbar {
    background: rgba(255,255,255,0.97);
    box-shadow: 0 2px 20px rgba(0,0,0,0.08);
}

.navbar-brand {
    font-weight: 700;
    color: var(--primary-color) !important;
    font-size: 1.5rem;
}

.nav-link {
    color: var(--text-dark) !important;
    font-weight: 500;
    margin: 0 0.5rem;
}

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

/* Hero Section */
.hero-section {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 8rem 0 5rem;
    position: relative;
    overflow: hidden;
    margin-top: 76px;
}

.hero-section::before {
    content: '';
    position: absolute;
    left: 0; right: 0; top: 0; bottom: 0;
    background: url('data:image/svg+xml,<svg width="100%" height="100%" viewBox="0 0 1440 320" fill="none" xmlns="http://www.w3.org/2000/svg"><path fill="%23f093fb" fill-opacity="0.2" d="M0,160L80,170.7C160,181,320,203,480,197.3C640,192,800,160,960,133.3C1120,107,1280,85,1360,74.7L1440,64L1440,320L1360,320C1280,320,1120,320,960,320C800,320,640,320,480,320C320,320,160,320,80,320L0,320Z"></path></svg>');
    background-size: cover;
    opacity: 0.7;
    z-index: 0;
}

.hero-content {
    position: relative;
    z-index: 1;
}

.hero-title {
    font-size: 2.8rem;
    font-weight: 800;
    margin-bottom: 1rem;
    letter-spacing: -1px;
}

.hero-tagline {
    font-size: 1.3rem;
    font-weight: 400;
    margin-bottom: 2rem;
    opacity: 0.95;
}

.hero-description {
    font-size: 1.1rem;
    margin-bottom: 2.5rem;
    opacity: 0.9;
    max-width: 600px;
}

.btn-hero {
    background: linear-gradient(45deg, #ff6b6b, #ee5a24);
    border: none;
    border-radius: 50px;
    padding: 1rem 2.5rem;
    font-weight: 600;
    font-size: 1.1rem;
    color: white;
    text-decoration: none;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
    transition: all 0.3s;
}

.btn-hero:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 25px rgba(255, 107, 107, 0.4);
    color: white;
}

.hero-illustration {
    text-align: center;
}

.hero-illustration i {
    font-size: 7rem;
    opacity: 0.18;
}

/* Stats Section */
.stats-section {
    background: white;
    padding: 3rem 0 2rem;
    margin-top: -2rem;
    z-index: 2;
    border-radius: 20px 20px 0 0;
    box-shadow: 0 2px 20px rgba(102,126,234,0.04);
}

.stat-card {
    text-align: center;
    padding: 2rem 1rem;
}

.stat-number {
    font-size: 2.2rem;
    font-weight: 700;
    color: #667eea;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1.1rem;
    color: #666;
    font-weight: 500;
}

/* Classes Section */
.classes-section {
    background: #fff;
    padding: 4rem 0 2rem;
}

.section-header {
    text-align: center;
    margin-bottom: 2rem;
}

.section-header h2 {
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.section-header p {
    color: #666;
    font-size: 1rem;
}

.classes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
}

.class-card {
    background: white;
    border-radius: 20px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    padding: 2rem 1.5rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
    overflow: hidden;
    height: 100%;
    animation: fadeInUp 0.5s;
    position: relative;
}

.class-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.15);
    background: linear-gradient(135deg, #f8f9ff 0%, #eaf3fc 100%);
}

.class-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.class-card:hover::before {
    transform: scaleX(1);
}

.class-icon {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
    transition: transform 0.3s ease;
}

.class-card:hover .class-icon {
    transform: scale(1.1);
}

.class-title {
    font-weight: 600;
    color: var(--text-dark);
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    line-height: 1.3;
}

.class-book-count {
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
}

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

/* Books Section */
.books-section {
    background: #fff;
    padding: 4rem 0 2rem;
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
}

.book-card {
    background: white;
    border-radius: 16px;
    box-shadow: 0 2px 12px rgba(42,123,228,0.07);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    transition: all 0.3s ease;
    animation: fadeInUp 0.5s;
    border: 1px solid rgba(102, 126, 234, 0.1);
}

.book-card:hover {
    box-shadow: 0 8px 24px rgba(42,123,228,0.13);
    background: #f8f9ff;
    transform: translateY(-3px);
}

.book-title {
    font-weight: 600;
    color: var(--primary-color);
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.book-author {
    color: #666;
    font-size: 0.95rem;
    margin-bottom: 1rem;
    font-style: italic;
}

.book-link {
    display: inline-flex;
    align-items: center;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    color: #fff;
    padding: 0.6rem 1.2rem;
    border-radius: 25px;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    font-size: 0.9rem;
}

.book-link:hover {
    background: linear-gradient(45deg, var(--secondary-color), var(--primary-color));
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.3);
}

.back-btn {
    background: none;
    border: none;
    color: var(--primary-color);
    font-weight: 500;
    font-size: 1rem;
    margin-bottom: 1rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: color 0.18s;
    padding: 0.5rem 1rem;
    border-radius: 25px;
}

.back-btn:hover {
    color: var(--secondary-color);
    background: rgba(102, 126, 234, 0.1);
}

/* How It Works */
.how-section {
    background: #f8f9fa;
    padding: 4rem 0 2rem;
}

.how-step {
    text-align: center;
    padding: 2rem 1rem;
}

.how-icon {
    font-size: 2.5rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

.how-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.how-desc {
    color: #666;
    font-size: 1rem;
}

/* Testimonial */
.testimonial-section {
    background: #fff;
    padding: 3rem 0 2rem;
}

.testimonial {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
    font-style: italic;
    color: #555;
    font-size: 1.1rem;
}

.testimonial-author {
    margin-top: 1rem;
    font-weight: 600;
    color: var(--primary-color);
}

/* Loading Popup */
.loading-popup {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 9999;
}

.loading-content {
    background: white;
    border-radius: 20px;
    padding: 2.5rem;
    text-align: center;
    max-width: 350px;
    margin: 1rem;
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
}

.loading-spinner {
    width: 50px;
    height: 50px;
    border: 4px solid #f3f3f3;
    border-top: 4px solid var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto 1rem;
}

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

.loading-text {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

.loading-subtext {
    color: var(--text-light);
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

/* Progress Bar Styles */
.progress-container {
    margin-top: 1.5rem;
}

.progress {
    height: 8px;
    background-color: #e9ecef;
    border-radius: 10px;
    overflow: hidden;
    margin-bottom: 0.5rem;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    border-radius: 10px;
    transition: width 0.5s ease;
    position: relative;
}

.progress-bar::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
    animation: shimmer 2s infinite;
}

@keyframes shimmer {
    0% { transform: translateX(-100%); }
    100% { transform: translateX(100%); }
}

.progress-text {
    font-size: 0.85rem;
    color: var(--text-light);
    font-weight: 500;
}

/* Bottom Navigation for Mobile */
.bottom-nav {
    display: none;
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: 0 -4px 20px rgba(0,0,0,0.15);
    z-index: 1000;
    padding: 0.8rem 0 1rem;
    border-top: 1px solid rgba(0,0,0,0.05);
    justify-content: space-around;
}

.bottom-nav-item {
    text-align: center;
    padding: 0.5rem;
    color: #8e9aaf;
    text-decoration: none;
    font-size: 0.75rem;
    font-weight: 500;
    transition: all 0.3s ease;
    border-radius: 12px;
    margin: 0 0.2rem;
}

.bottom-nav-item:hover {
    color: var(--primary-color);
    background: rgba(102, 126, 234, 0.1);
}

.bottom-nav-item.active {
    color: var(--primary-color);
    background: rgba(102, 126, 234, 0.15);
}

.bottom-nav-item i {
    display: block;
    font-size: 1.3rem;
    margin-bottom: 0.3rem;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .hero-title { font-size: 2rem; }
    .hero-section { padding: 5rem 0 3rem; }
    .stats-section { padding: 2rem 0 1rem; }
    .classes-section { padding: 2rem 0 1rem; }
    .how-section { padding: 2rem 0 1rem; }
    .testimonial-section { padding: 2rem 0 1rem; }
    .navbar-nav { display: none; }
    .bottom-nav { display: flex; }
    .classes-grid, .books-grid {
        grid-template-columns: 1fr;
    }
    .class-card {
        padding: 1.5rem 1rem;
    }
    .loading-content {
        padding: 2rem;
        max-width: 300px;
    }
}

@media (max-width: 576px) {
    .hero-title { font-size: 1.3rem; }
    .hero-section { padding: 3rem 0 2rem; }
    .stats-section, .classes-section, .how-section, .testimonial-section { 
        padding: 1.2rem 0 0.5rem; 
    }
    .class-card {
        padding: 1.2rem 0.8rem;
    }
    .book-card {
        padding: 1.2rem;
    }
    .loading-content {
        padding: 1.5rem;
        max-width: 280px;
    }
    .loading-text {
        font-size: 1.1rem;
    }
    
    /* Internet status bar mobile styles */
    .internet-status-bar {
        padding: 10px 15px;
    }
    
    .status-content {
        gap: 8px;
        font-size: 0.9rem;
    }
    
    .status-text {
        font-size: 0.85rem;
    }
    
    .status-retry-btn {
        padding: 4px 8px;
        font-size: 0.75rem;
    }
}

/* Internet Status Bar */
.internet-status-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 9999;
    transform: translateY(-100%);
    transition: transform 0.3s ease;
    background: linear-gradient(45deg, #ff6b6b, #ee5a24);
    color: white;
    padding: 12px 20px;
    box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
}

.internet-status-bar.offline {
    background: linear-gradient(45deg, #ff6b6b, #ee5a24);
    transform: translateY(0);
}

.internet-status-bar.online {
    background: linear-gradient(45deg, #00b894, #00a085);
}

.status-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    font-weight: 500;
}

.status-icon {
    font-size: 1.2rem;
    animation: pulse 2s infinite;
}

.status-text {
    font-size: 0.95rem;
}

.status-retry-btn {
    background: rgba(255, 255, 255, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.3);
    color: white;
    padding: 6px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 5px;
}

.status-retry-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.7; }
}

html { scroll-behavior: smooth; }