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

:root {
    --primary-color: #6366F1;
    --primary-dark: #4F46E5;
    --secondary-color: #10B981;
    --accent-color: #F59E0B;
    --text-primary: #1F2937;
    --text-secondary: #6B7280;
    --text-light: #9CA3AF;
    --bg-primary: #FFFFFF;
    --bg-secondary: #F9FAFB;
    --bg-accent: #F3F4F6;
    --border-color: #E5E7EB;
    --border-light: #F3F4F6;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Header Styles */
.header {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    padding: 1rem 0;
}

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

.nav-brand {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--text-primary);
    font-weight: 700;
    font-size: 1.25rem;
}

.logo {
    width: 32px;
    height: 32px;
    margin-right: 0.5rem;
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.2s;
}

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

.nav-toggle {
    display: none;
    background: none;
    border: none;
    flex-direction: column;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 20px;
    height: 2px;
    background: var(--text-primary);
    margin: 2px 0;
    transition: 0.3s;
}

/* Button Styles */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    cursor: pointer;
    border: none;
    transition: all 0.2s;
    font-size: 0.875rem;
}

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

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

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

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1rem;
}

/* Hero Section */
.hero {
    padding: 4rem 0;
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-accent) 100%);
}

.hero .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.hero-content h1 {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.hero-content p {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.hero-image img {
    width: 100%;
    height: auto;
}

/* Features Section */
.features {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.features h2 {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

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

.feature {
    text-align: center;
    padding: 2rem;
    border-radius: var(--radius-lg);
    background: var(--bg-secondary);
}

.feature-icon {
    margin-bottom: 1rem;
}

.feature h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature p {
    color: var(--text-secondary);
}

/* Course Styles */
.featured-courses {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.featured-courses h2 {
    text-align: center;
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.course-card {
    background: var(--bg-primary);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s;
    text-decoration: none;
    color: inherit;
}

.course-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.course-image {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.course-content {
    padding: 1.5rem;
}

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

.course-category {
    background: var(--primary-color);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 600;
}

.course-difficulty {
    background: var(--bg-accent);
    color: var(--text-secondary);
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 500;
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.course-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-size: 0.875rem;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    font-size: 0.875rem;
    color: var(--text-light);
}

.course-price {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* CTA Section */
.cta {
    padding: 5rem 0;
    background: var(--primary-color);
    color: white;
}

.cta .container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

.cta-content h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
}

.cta-content p {
    font-size: 1.125rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

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

.cta .btn-primary:hover {
    background: var(--bg-accent);
}

.cta-image img {
    width: 100%;
    height: auto;
}

/* Footer */
.footer {
    background: var(--text-primary);
    color: white;
    padding: 3rem 0 1rem;
}

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

.footer-section h3,
.footer-section h4 {
    margin-bottom: 1rem;
    font-weight: 600;
}

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

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

.footer-section a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: color 0.2s;
}

.footer-section a:hover {
    color: white;
}

.footer-contact p {
    margin-bottom: 0.5rem;
    font-size: 0.875rem;
}

.footer-bottom {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    padding-top: 1rem;
    text-align: center;
    color: rgba(255, 255, 255, 0.7);
}

/* Utility Classes */
.text-center {
    text-align: center;
}

.text-left {
    text-align: left;
}

.text-right {
    text-align: right;
}

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

/* Form Styles */
.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--text-primary);
}

.form-input {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-input.error {
    border-color: #EF4444;
}

.form-error {
    color: #EF4444;
    font-size: 0.875rem;
    margin-top: 0.25rem;
}

.form-checkbox {
    display: flex;
    align-items: flex-start;
    gap: 0.5rem;
}

.form-checkbox input {
    margin-top: 0.25rem;
}

/* Course Detail Styles */
.course-detail {
    padding: 2rem 0;
}

.course-detail-header {
    background: var(--bg-secondary);
    padding: 3rem 0;
    margin-bottom: 3rem;
}

.course-detail-content {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
}

.course-detail-main h2 {
    font-size: 1.75rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.course-detail-sidebar {
    background: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    height: fit-content;
    position: sticky;
    top: 100px;
}

.course-info-list {
    list-style: none;
    margin-bottom: 2rem;
}

.course-info-list li {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-light);
}

.course-info-list li:last-child {
    border-bottom: none;
}

.curriculum-list {
    list-style: none;
}

.curriculum-list li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-light);
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.curriculum-list li:last-child {
    border-bottom: none;
}

.lesson-number {
    background: var(--primary-color);
    color: white;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 600;
}

/* FAQ Styles */
.faq-item {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 1rem;
}

.faq-question {
    background: none;
    border: none;
    width: 100%;
    padding: 1.5rem;
    text-align: left;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.faq-question:hover {
    background: var(--bg-secondary);
}

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    display: none;
}

.faq-answer.active {
    display: block;
}

.faq-icon {
    transition: transform 0.3s;
}

.faq-question.active .faq-icon {
    transform: rotate(180deg);
}

/* Checkout Styles */
.checkout {
    padding: 2rem 0;
    background: var(--bg-secondary);
    min-height: 80vh;
}

.checkout-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 0 1rem;
}

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

.checkout-steps {
    display: flex;
    justify-content: center;
    margin-bottom: 3rem;
}

.step {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    border-radius: var(--radius-md);
    background: var(--bg-accent);
    color: var(--text-secondary);
    margin: 0 0.5rem;
}

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

.checkout-form {
    background: var(--bg-primary);
    padding: 2rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.order-summary {
    background: var(--bg-secondary);
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    margin-bottom: 2rem;
}

.order-summary h3 {
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.order-item {
    display: flex;
    justify-content: space-between;
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-light);
}

.order-total {
    display: flex;
    justify-content: space-between;
    padding: 1rem 0;
    font-weight: 700;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.payment-icons {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    margin-top: 1rem;
}

.payment-icon {
    width: 40px;
    height: 24px;
    background: var(--bg-accent);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-secondary);
}

/* Search and Filter Styles */
.search-filters {
    background: var(--bg-primary);
    padding: 2rem 0;
    border-bottom: 1px solid var(--border-color);
}

.search-form {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.search-input {
    flex: 1;
    min-width: 200px;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
}

.filter-select {
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-size: 1rem;
    background: white;
    min-width: 150px;
}

.results-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--text-secondary);
    flex-wrap: wrap;
    gap: 1rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--bg-primary);
        flex-direction: column;
        padding: 1rem;
        box-shadow: var(--shadow-md);
        gap: 1rem;
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-toggle {
        display: flex;
    }

    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .hero-content h1 {
        font-size: 2rem;
    }

    .cta .container {
        grid-template-columns: 1fr;
        text-align: center;
    }

    .cta-content h2 {
        font-size: 2rem;
    }

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

    .course-detail-sidebar {
        position: static;
    }

    .form-row {
        grid-template-columns: 1fr;
    }

    .search-form {
        flex-direction: column;
    }

    .results-info {
        flex-direction: column;
        align-items: flex-start;
    }

    .hero-actions {
        justify-content: center;
    }

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

@media (max-width: 480px) {
    .container {
        padding: 0 0.75rem;
    }

    .hero {
        padding: 2rem 0;
    }

    .features,
    .featured-courses {
        padding: 3rem 0;
    }

    .features h2,
    .featured-courses h2 {
        font-size: 2rem;
    }

    .checkout-form {
        padding: 1rem;
    }

    .checkout-steps {
        flex-direction: column;
        align-items: center;
    }

    .step {
        margin: 0.25rem 0;
    }
}