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

:root {
    --primary-color: hsl(240, 100%, 60%);
    --primary-dark: hsl(240, 100%, 50%);
    --secondary-color: hsl(200, 100%, 50%);
    --accent-color: hsl(45, 100%, 55%);
    --text-color: hsl(220, 15%, 25%);
    --text-light: hsl(220, 10%, 45%);
    --border-color: hsl(220, 15%, 85%);
    --bg-light: hsl(220, 30%, 98%);
    --bg-white: hsl(0, 0%, 100%);
    --shadow: 0 2px 10px hsla(220, 15%, 25%, 0.1);
    --shadow-hover: 0 4px 20px hsla(220, 15%, 25%, 0.15);
    --border-radius: 8px;
    --transition: all 0.3s ease;
}

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

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

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

.nav-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 0;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-color);
    font-weight: 700;
    font-size: 1.25rem;
}

.nav {
    display: flex;
    gap: 2rem;
    align-items: center;
}

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

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--primary-color);
    border-radius: 1px;
}

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

.mobile-menu-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-color);
    margin: 3px 0;
    transition: var(--transition);
    border-radius: 2px;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    border: 2px solid transparent;
    cursor: pointer;
    font-size: 1rem;
    text-align: center;
    justify-content: center;
}

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

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

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

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

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

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

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

.hero-content p {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 2rem;
    line-height: 1.6;
}

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

.hero-image img {
    width: 100%;
    height: auto;
    border-radius: var(--border-radius);
}

/* Features Section */
.features {
    padding: 4rem 0;
    background: var(--bg-white);
}

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

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

.feature-card {
    text-align: center;
    padding: 2rem;
    border-radius: var(--border-radius);
    background: var(--bg-white);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

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

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

.feature-card h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-color);
}

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

/* Featured Courses */
.featured-courses {
    padding: 4rem 0;
    background: var(--bg-light);
}

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

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

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

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

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

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

.course-label {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--accent-color);
    color: var(--text-color);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.course-content {
    padding: 1.5rem;
}

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

.course-category,
.course-difficulty {
    font-size: 0.875rem;
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-weight: 500;
}

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

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

.course-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-color);
}

.course-card p {
    color: var(--text-light);
    margin-bottom: 1.5rem;
    line-height: 1.5;
}

.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-light);
    font-size: 0.875rem;
}

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

.section-footer {
    text-align: center;
}

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

.search-filter .container {
    display: flex;
    gap: 1rem;
    align-items: center;
    flex-wrap: wrap;
}

.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);
    background: var(--bg-white);
}

.search-input {
    flex: 1;
    min-width: 250px;
}

.search-input:focus,
.filter-select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px hsla(240, 100%, 60%, 0.1);
}

.filter-select {
    min-width: 150px;
}

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

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

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

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

.course-info p {
    font-size: 1.125rem;
    color: var(--text-light);
    line-height: 1.6;
    margin-bottom: 2rem;
}

.course-sidebar {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: var(--border-radius);
    height: fit-content;
}

.course-sidebar img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: var(--border-radius);
    margin-bottom: 1.5rem;
}

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

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

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

.course-details-list li {
    display: flex;
    justify-content: space-between;
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--border-color);
}

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

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

.course-content-section h2 {
    font-size: 2rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    color: var(--text-color);
}

.learning-objectives,
.requirements-list,
.curriculum-list {
    list-style: none;
}

.learning-objectives li,
.requirements-list li {
    padding: 0.5rem 0;
    position: relative;
    padding-left: 2rem;
}

.learning-objectives li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

.requirements-list li::before {
    content: '•';
    position: absolute;
    left: 0;
    color: var(--text-light);
}

.curriculum-item {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 0.5rem;
    overflow: hidden;
}

.curriculum-header {
    padding: 1rem 1.5rem;
    background: var(--bg-light);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.curriculum-header:hover {
    background: var(--border-color);
}

.instructor-section {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: var(--border-radius);
    margin-bottom: 3rem;
}

.instructor-info {
    display: flex;
    gap: 1.5rem;
    align-items: flex-start;
}

.instructor-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: var(--primary-color);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 2rem;
    font-weight: bold;
    flex-shrink: 0;
}

.instructor-details h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-color);
}

.faq-section .faq-item {
    background: var(--bg-white);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius);
    margin-bottom: 0.5rem;
    overflow: hidden;
}

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

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

.faq-answer {
    padding: 1rem 1.5rem;
    display: none;
}

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

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

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

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

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px hsla(240, 100%, 60%, 0.1);
}

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

/* Footer */
.footer {
    background: var(--text-color);
    color: white;
    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-logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 1rem;
    font-weight: 700;
    font-size: 1.25rem;
}

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

.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: var(--transition);
}

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
    color: rgba(255, 255, 255, 0.8);
}

/* Content Pages */
.page-header {
    background: var(--bg-light);
    padding: 3rem 0;
    text-align: center;
}

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

.page-content {
    padding: 3rem 0;
    max-width: 800px;
    margin: 0 auto;
}

.page-content h2 {
    font-size: 2rem;
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-color);
}

.page-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 1.5rem 0 1rem;
    color: var(--text-color);
}

.page-content p {
    margin-bottom: 1rem;
    line-height: 1.7;
    color: var(--text-light);
}

.page-content ul,
.page-content ol {
    margin: 1rem 0 1rem 2rem;
    color: var(--text-light);
}

.page-content li {
    margin-bottom: 0.5rem;
    line-height: 1.6;
}

/* Contact Form */
.contact-info {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

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

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

.contact-form {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav {
        display: none;
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
    }
    
    .hero-content h1 {
        font-size: 2rem;
    }
    
    .hero-actions {
        justify-content: center;
    }
    
    .features h2,
    .featured-courses h2 {
        font-size: 2rem;
    }
    
    .course-header {
        grid-template-columns: 1fr;
    }
    
    .course-info h1 {
        font-size: 2rem;
    }
    
    .instructor-info {
        flex-direction: column;
        text-align: center;
    }
    
    .search-filter .container {
        flex-direction: column;
        align-items: stretch;
    }
    
    .search-input {
        min-width: auto;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }
    
    .hero {
        padding: 2rem 0;
    }
    
    .hero-content h1 {
        font-size: 1.75rem;
    }
    
    .hero-actions {
        flex-direction: column;
    }
    
    .courses-grid {
        grid-template-columns: 1fr;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        grid-template-columns: 1fr;
    }
}

/* 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,
.nav-link:focus,
input:focus,
textarea:focus,
select:focus {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}