* {
    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%, 60%);
    --text-primary: hsl(220, 20%, 20%);
    --text-secondary: hsl(220, 10%, 50%);
    --text-light: hsl(220, 10%, 70%);
    --bg-primary: hsl(0, 0%, 100%);
    --bg-secondary: hsl(220, 20%, 98%);
    --bg-accent: hsl(220, 30%, 96%);
    --border-color: hsl(220, 10%, 90%);
    --shadow-light: 0 2px 10px hsla(220, 20%, 20%, 0.1);
    --shadow-medium: 0 4px 20px hsla(220, 20%, 20%, 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-primary);
    background-color: var(--bg-primary);
}

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

/* Header */
.header {
    background-color: var(--bg-primary);
    box-shadow: var(--shadow-light);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.nav-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem 20px;
    max-width: 1200px;
    margin: 0 auto;
}

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

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    margin: 0;
}

.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);
}

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

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

/* 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: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

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

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

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.875rem 1.75rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    transition: var(--transition);
    border: none;
    cursor: pointer;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-medium);
}

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

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

/* Features Section */
.features {
    padding: 5rem 0;
}

.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(--border-radius);
    background-color: var(--bg-secondary);
    transition: var(--transition);
}

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

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

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

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

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

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

.courses-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

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

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

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

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

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

.course-content {
    padding: 1.5rem;
}

.course-content h3 {
    margin-bottom: 0.5rem;
}

.course-content h3 a {
    text-decoration: none;
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 600;
}

.course-content h3 a:hover {
    color: var(--primary-color);
}

.course-category {
    color: var(--primary-color);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

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

.course-meta {
    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-actions {
    display: flex;
    gap: 0.75rem;
}

/* CTA Section */
.cta {
    padding: 5rem 0;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
}

.cta-content {
    text-align: center;
}

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

.cta-content p {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

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

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

/* Footer */
.footer {
    background-color: 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;
    color: white;
}

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

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

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

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

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

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid hsl(220, 10%, 30%);
    color: var(--text-light);
}

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

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

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

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

.search-box {
    position: relative;
    flex: 1;
    min-width: 300px;
    max-width: 400px;
}

.search-input {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

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

.filter-select {
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    background-color: white;
    cursor: pointer;
    transition: var(--transition);
}

.filter-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* 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,
.form-textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-family: inherit;
    transition: var(--transition);
}

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

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

/* Course Detail Styles */
.course-header {
    background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-accent) 100%);
    padding: 3rem 0;
}

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

.course-title {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.course-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

.course-meta-info {
    display: flex;
    gap: 2rem;
    flex-wrap: wrap;
    margin-bottom: 2rem;
}

.meta-item {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.meta-label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.meta-value {
    font-weight: 600;
    color: var(--text-primary);
}

.course-sidebar {
    background-color: var(--bg-primary);
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-light);
    position: sticky;
    top: 100px;
}

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

.course-price-large {
    font-size: 3rem;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 0.5rem;
}

.course-detail-sections {
    padding: 3rem 0;
}

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

.section-title {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 1.5rem;
    color: var(--text-primary);
}

.learning-outcomes {
    list-style: none;
}

.learning-outcomes li {
    padding: 0.5rem 0;
    padding-left: 2rem;
    position: relative;
}

.learning-outcomes li::before {
    content: "✓";
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
    font-size: 1.2rem;
}

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

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

.curriculum-header {
    padding: 1rem 1.5rem;
    background-color: var(--bg-accent);
    font-weight: 600;
    color: var(--text-primary);
}

.curriculum-content {
    padding: 1rem 1.5rem;
    color: var(--text-secondary);
}

.instructor-card {
    background-color: var(--bg-secondary);
    padding: 2rem;
    border-radius: var(--border-radius);
    display: flex;
    gap: 2rem;
    align-items: center;
}

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

.instructor-info h3 {
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.instructor-bio {
    color: var(--text-secondary);
    line-height: 1.6;
}

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

.faq-item {
    border-bottom: 1px solid var(--border-color);
    padding: 1.5rem 0;
}

.faq-question {
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    font-size: 1.1rem;
}

.faq-answer {
    color: var(--text-secondary);
    line-height: 1.6;
}

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

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

    .nav-toggle {
        display: flex;
    }

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

    .hero-content h1 {
        font-size: 2.5rem;
    }

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

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

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

    .course-meta-info {
        justify-content: center;
        text-align: center;
    }

    .search-filter-container {
        flex-direction: column;
        align-items: stretch;
    }

    .search-box {
        min-width: auto;
        max-width: none;
    }

    .instructor-card {
        flex-direction: column;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 15px;
    }

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

    .hero-content p {
        font-size: 1.1rem;
    }

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

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

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

    .course-sidebar {
        position: static;
        margin-top: 2rem;
    }
}