/* ===========================
   Global Styles & Variables
   =========================== */
:root {
    --primary-color: #8b5cf6;
    --primary-dark: #7c3aed;
    --secondary-color: #10b981;
    --dark-bg: #0f172a;
    --darker-bg: #020617;
    --card-bg: #1e293b;
    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --border-color: #334155;
    --success-color: #22c55e;
    --warning-color: #f59e0b;
    --danger-color: #ef4444;
    --transition: all 0.3s ease;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background-color: var(--dark-bg);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 20px;
}

/* ===========================
   Ad Sections
   =========================== */
.ad-section {
    padding: 2rem 0;
    background-color: var(--darker-bg);
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
}

.ad-container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 1rem;
    text-align: center;
    background-color: var(--card-bg);
    border-radius: 8px;
    border: 1px solid var(--border-color);
}

.ad-container ins {
    min-height: 90px;
    display: block;
}

/* Sidebar ads */
.sidebar-ad {
    position: sticky;
    top: 100px;
    margin: 2rem 0;
}

@media (max-width: 768px) {
    .ad-section {
        padding: 1rem 0;
    }
    
    .ad-container {
        margin: 1rem auto;
    }
}

/* ===========================
   Header & Navigation
   =========================== */
.header {
    background-color: var(--darker-bg);
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.navbar {
    padding: 1rem 0;
}

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

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.logo i {
    font-size: 2rem;
}

.logo small {
    font-size: 0.75rem;
    color: var(--text-secondary);
    font-weight: 400;
}

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

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
}

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

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-color);
    transition: var(--transition);
}

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

.hamburger {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
}

.hamburger span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    transition: var(--transition);
}

/* ===========================
   Hero Section
   =========================== */
.hero {
    background: linear-gradient(135deg, var(--darker-bg) 0%, var(--dark-bg) 100%);
    padding: 80px 0;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(circle at 20% 50%, rgba(139, 92, 246, 0.1) 0%, transparent 50%);
}

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

.hero-title {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 4rem;
    flex-wrap: wrap;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.stat-label {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-top: 0.5rem;
}

/* ===========================
   Search & Filter Section
   =========================== */
.search-section {
    padding: 3rem 0;
    background-color: var(--card-bg);
}

.search-wrapper {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.search-box {
    display: flex;
    align-items: center;
    background: var(--dark-bg);
    border-radius: 50px;
    padding: 1rem 1.5rem;
    border: 2px solid var(--border-color);
    transition: var(--transition);
}

.search-box:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.search-box i {
    color: var(--text-secondary);
    margin-right: 1rem;
    font-size: 1.2rem;
}

.search-box input {
    flex: 1;
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 1rem;
}

.search-box input::placeholder {
    color: var(--text-secondary);
}

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

.filter-btn {
    padding: 0.75rem 1.5rem;
    background: var(--dark-bg);
    border: 2px solid var(--border-color);
    color: var(--text-secondary);
    border-radius: 30px;
    cursor: pointer;
    font-weight: 500;
    transition: var(--transition);
}

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

/* ===========================
   Courses Section
   =========================== */
.courses-section {
    padding: 4rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 3rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.section-header p {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: var(--card-bg);
    border-radius: 12px;
    overflow: hidden;
    transition: var(--transition);
    border: 1px solid var(--border-color);
    cursor: pointer;
}

.course-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 12px 24px rgba(139, 92, 246, 0.2);
    border-color: var(--primary-color);
}

.course-image {
    width: 100%;
    height: 180px;
    object-fit: cover;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
}

.course-content {
    padding: 1.5rem;
}

.course-category {
    display: inline-block;
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    text-transform: uppercase;
}

.course-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.course-instructor {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.course-rating {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--warning-color);
}

.course-students {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.course-footer {
    padding: 1rem 1.5rem;
    background: var(--dark-bg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.course-price {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.original-price {
    text-decoration: line-through;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.free-price {
    color: var(--success-color);
    font-weight: 700;
    font-size: 1.2rem;
}

.enroll-btn {
    background: var(--primary-color);
    color: white;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-decoration: none;
    display: inline-block;
}

.enroll-btn:hover {
    background: var(--primary-dark);
    transform: scale(1.05);
}

.load-more-wrapper {
    text-align: center;
}

.load-more-btn {
    background: var(--card-bg);
    color: var(--text-primary);
    padding: 1rem 3rem;
    border: 2px solid var(--primary-color);
    border-radius: 30px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    font-size: 1rem;
}

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

/* ===========================
   Categories Section
   =========================== */
.categories-section {
    padding: 4rem 0;
    background: var(--card-bg);
}

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

.category-card {
    background: var(--dark-bg);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    cursor: pointer;
    transition: var(--transition);
    border: 2px solid var(--border-color);
}

.category-card:hover {
    border-color: var(--primary-color);
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(139, 92, 246, 0.2);
}

.category-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.category-card h3 {
    font-size: 1.3rem;
    margin-bottom: 0.5rem;
}

.category-card p {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

/* ===========================
   About Section
   =========================== */
.about-section {
    padding: 4rem 0;
}

.about-content {
    max-width: 800px;
    margin: 0 auto;
    text-align: center;
}

.about-content h2 {
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
}

.about-content p {
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 2rem;
    line-height: 1.8;
}

.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.feature-item {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    background: var(--card-bg);
    padding: 1rem 1.5rem;
    border-radius: 8px;
}

.feature-item i {
    color: var(--success-color);
    font-size: 1.5rem;
}

/* ===========================
   Footer
   =========================== */
.footer {
    background: var(--darker-bg);
    padding: 3rem 0 1rem;
    margin-top: 4rem;
}

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

.footer-section h4 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.footer-section p {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.6;
}

.footer-section ul {
    list-style: none;
}

.footer-section ul li {
    margin-bottom: 0.5rem;
}

.footer-section ul li a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: var(--transition);
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.social-links {
    display: flex;
    gap: 1rem;
    margin-top: 1rem;
}

.social-links a {
    width: 40px;
    height: 40px;
    background: var(--card-bg);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-primary);
    transition: var(--transition);
}

.social-links a:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
}

.footer-bottom {
    border-top: 1px solid var(--border-color);
    padding-top: 1.5rem;
    text-align: center;
    color: var(--text-secondary);
}

.footer-bottom p {
    margin-bottom: 0.5rem;
}

.disclaimer {
    font-size: 0.85rem;
    opacity: 0.7;
}

/* ===========================
   Back to Top Button
   =========================== */
.back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-color);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    box-shadow: 0 4px 12px rgba(139, 92, 246, 0.3);
    z-index: 999;
}

.back-to-top.show {
    opacity: 1;
    visibility: visible;
}

.back-to-top:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 16px rgba(139, 92, 246, 0.5);
}

/* ===========================
   Responsive Design
   =========================== */
@media (max-width: 768px) {
    .hamburger {
        display: flex;
    }

    .nav-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--darker-bg);
        flex-direction: column;
        padding: 2rem;
        gap: 1rem;
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: var(--transition);
    }

    .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .hero-title {
        font-size: 2.5rem;
    }

    .hero-subtitle {
        font-size: 1rem;
    }

    .hero-stats {
        gap: 2rem;
    }

    .stat-number {
        font-size: 2rem;
    }

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

    .filter-buttons {
        justify-content: flex-start;
        overflow-x: auto;
        flex-wrap: nowrap;
        padding-bottom: 0.5rem;
    }

    .filter-btn {
        flex-shrink: 0;
    }

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

    .footer-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }

    .logo span {
        font-size: 1.2rem;
    }

    .logo small {
        display: none;
    }
}

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

.course-card {
    animation: fadeIn 0.5s ease-out;
}

/* Loading Spinner */
.loading {
    display: inline-block;
    width: 40px;
    height: 40px;
    border: 4px solid var(--border-color);
    border-top-color: var(--primary-color);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}