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

:root {
    --primary-color: #6366f1;
    --primary-dark: #4f46e5;
    --secondary-color: #f8fafc;
    --accent-color: #06b6d4;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --background-light: #f8fafc;
    --white: #ffffff;
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1);
    --border-radius: 8px;
    --border-radius-lg: 12px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--white);
}

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

/* Header & Navigation */
.header {
    background: var(--white);
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav {
    padding: 1rem 0;
}

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

.nav-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    text-decoration: none;
    color: var(--text-primary);
}

.logo, .footer-logo {
    width: 40px;
    height: 40px;
}

.brand-name, .footer-brand-name {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

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

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-primary);
    margin: 3px 0;
    transition: var(--transition);
}

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

.nav-link {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: var(--transition);
    padding: 0.5rem 0;
}

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

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.875rem;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
    min-height: 44px;
}

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

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

.btn-secondary {
    background: var(--secondary-color);
    color: var(--text-primary);
    border-color: var(--border-color);
}

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

.btn-outline {
    background: transparent;
    color: var(--primary-color);
    border-color: var(--primary-color);
}

.btn-outline:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-1px);
}

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

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

.hero-title {
    font-size: 3rem;
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
    line-height: 1.7;
}

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

.hero-image {
    display: flex;
    justify-content: center;
}

.hero-bg {
    width: 100%;
    max-width: 500px;
    height: auto;
}

/* Sections */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.section-actions {
    text-align: center;
    margin-top: 3rem;
}

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

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

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

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

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

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

/* Courses */
.featured-courses {
    padding: 5rem 0;
    background: var(--background-light);
}

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

.course-card {
    background: var(--white);
    border-radius: var(--border-radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.course-image {
    position: relative;
    height: 200px;
    overflow: hidden;
}

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

.course-label {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--primary-color);
    color: var(--white);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 600;
}

.course-content {
    padding: 1.5rem;
}

.course-meta {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.course-category,
.course-difficulty {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-weight: 500;
}

.course-category {
    background: var(--accent-color);
    color: var(--white);
}

.course-difficulty {
    background: var(--background-light);
    color: var(--text-secondary);
}

.course-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}

.course-description {
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
    line-height: 1.6;
}

.course-details {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.course-duration {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.course-price {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* Course Detail Page */
.course-header {
    padding: 3rem 0;
    background: var(--background-light);
}

.course-hero {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    align-items: start;
}

.course-info h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.course-info .course-meta {
    margin-bottom: 1.5rem;
}

.course-info .course-description {
    font-size: 1.125rem;
    margin-bottom: 2rem;
}

.course-sidebar {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-md);
    position: sticky;
    top: 100px;
}

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

.course-price-section .course-price {
    font-size: 2rem;
    display: block;
    margin-bottom: 1rem;
}

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

.course-features li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    border-bottom: 1px solid var(--border-color);
}

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

.course-body {
    padding: 3rem 0;
}

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

.course-section {
    margin-bottom: 3rem;
}

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

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

.course-section li {
    padding: 0.5rem 0;
    color: var(--text-secondary);
    position: relative;
    padding-left: 1.5rem;
}

.course-section li:before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--success);
    font-weight: bold;
}

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

.curriculum-list li {
    background: var(--background-light);
    padding: 1rem;
    margin-bottom: 0.5rem;
    border-radius: var(--border-radius);
    border-left: 4px solid var(--primary-color);
}

.curriculum-list li:before {
    display: none;
}

.instructor-card {
    background: var(--white);
    padding: 2rem;
    border-radius: var(--border-radius-lg);
    box-shadow: var(--shadow-sm);
}

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

/* Search & Filter */
.search-filter {
    padding: 2rem 0;
    background: var(--background-light);
}

.search-controls {
    display: grid;
    grid-template-columns: 1fr auto auto;
    gap: 1rem;
    align-items: center;
    margin-bottom: 2rem;
}

.search-input,
.filter-select {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.search-input:focus,
.filter-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgb(99 102 241 / 0.1);
}

.results-count {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

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

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

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

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgb(99 102 241 / 0.1);
}

.form-textarea {
    resize: vertical;
    min-height: 120px;
}

/* FAQ */
.faq-item {
    background: var(--white);
    border-radius: var(--border-radius);
    margin-bottom: 1rem;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
}

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

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

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
    display: none;
}

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

.faq-icon {
    transition: var(--transition);
}

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

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

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

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

.footer-content {
    display: grid;
    grid-template-columns: 2fr 1fr 1fr 1.5fr;
    gap: 2rem;
    margin-bottom: 2rem;
}

.footer-section h4 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--white);
}

.footer-description {
    color: var(--text-muted);
    line-height: 1.6;
    margin-top: 1rem;
}

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

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

.footer-links a {
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: var(--white);
}

.contact-info p {
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

.contact-info a {
    color: var(--text-muted);
    text-decoration: none;
    transition: var(--transition);
}

.contact-info a:hover {
    color: var(--white);
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid #374151;
    color: var(--text-muted);
}

.footer-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

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

    .nav-menu {
        position: fixed;
        top: 100%;
        left: 0;
        width: 100%;
        background: var(--white);
        flex-direction: column;
        padding: 2rem 1rem;
        box-shadow: var(--shadow-lg);
        transform: translateX(-100%);
        transition: var(--transition);
    }

    .nav-menu.active {
        transform: translateX(0);
    }

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

    .hero-title {
        font-size: 2rem;
    }

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

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

    .course-sidebar {
        position: static;
        order: -1;
    }

    .search-controls {
        grid-template-columns: 1fr;
    }

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

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

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

    .section-title {
        font-size: 2rem;
    }
}

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

    .hero {
        padding: 2rem 0;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .btn {
        padding: 0.625rem 1.25rem;
        font-size: 0.8rem;
    }

    .course-card {
        margin: 0 -0.5rem;
    }

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

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* Focus styles */
*:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

.btn:focus,
.form-input:focus,
.form-textarea:focus,
.search-input:focus,
.filter-select:focus {
    outline: none;
    box-shadow: 0 0 0 3px rgb(99 102 241 / 0.3);
}