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

:root {
    --primary-color: hsl(220, 90%, 56%);
    --primary-dark: hsl(220, 90%, 45%);
    --secondary-color: hsl(280, 70%, 60%);
    --accent-color: hsl(45, 100%, 60%);
    --text-dark: hsl(220, 20%, 20%);
    --text-medium: hsl(220, 10%, 50%);
    --text-light: hsl(220, 10%, 70%);
    --bg-white: hsl(0, 0%, 100%);
    --bg-light: hsl(220, 20%, 98%);
    --bg-section: hsl(220, 30%, 96%);
    --border-light: hsl(220, 20%, 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;
    --border-radius-lg: 12px;
    --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-dark);
    background-color: var(--bg-white);
}

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

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

.nav {
    padding: 1rem 0;
}

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

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

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

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

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

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -0.5rem;
    left: 0;
    right: 0;
    height: 2px;
    background-color: var(--primary-color);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.25rem;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background-color: var(--text-dark);
    margin: 2px 0;
    transition: var(--transition);
}

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

.hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: center;
}

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

.hero-description {
    font-size: 1.25rem;
    color: var(--text-medium);
    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-lg);
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.875rem 2rem;
    border-radius: var(--border-radius);
    text-decoration: none;
    font-weight: 600;
    text-align: center;
    transition: var(--transition);
    border: 2px solid transparent;
    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);
}

.btn-secondary {
    background-color: transparent;
    color: var(--text-dark);
    border-color: var(--border-light);
}

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

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

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

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

.features {
    padding: 5rem 0;
    background-color: var(--bg-white);
}

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

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

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

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

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

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

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

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

.course-card {
    background-color: var(--bg-white);
    border-radius: var(--border-radius-lg);
    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-dark);
    padding: 0.25rem 0.75rem;
    border-radius: 20px;
    font-size: 0.875rem;
    font-weight: 600;
}

.course-content {
    padding: 1.5rem;
}

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

.course-category {
    background-color: var(--bg-section);
    color: var(--primary-color);
    padding: 0.25rem 0.75rem;
    border-radius: 15px;
    font-size: 0.875rem;
    font-weight: 500;
}

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

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

.course-description {
    color: var(--text-medium);
    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-light);
}

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

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

/* Trust Section */
.trust-section {
    padding: 5rem 0;
    background-color: var(--bg-white);
}

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

.trust-item {
    text-align: center;
    padding: 2rem;
}

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

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

.trust-item p {
    color: var(--text-medium);
    line-height: 1.6;
}

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

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

.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;
    font-weight: 700;
    font-size: 1.25rem;
    margin-bottom: 1rem;
}

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

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

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

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

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

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

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

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

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

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

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

/* Course Catalog Styles */
.page-header {
    background: linear-gradient(135deg, var(--bg-light) 0%, var(--bg-section) 100%);
    padding: 3rem 0;
    text-align: center;
}

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

.page-description {
    font-size: 1.125rem;
    color: var(--text-medium);
    max-width: 600px;
    margin: 0 auto;
}

.filters {
    padding: 2rem 0;
    background-color: var(--bg-white);
    border-bottom: 1px solid var(--border-light);
}

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

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

.search-input {
    flex: 1;
    min-width: 300px;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-light);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

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

.category-filters {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.category-btn {
    padding: 0.5rem 1rem;
    background-color: var(--bg-light);
    color: var(--text-medium);
    border: 1px solid var(--border-light);
    border-radius: 20px;
    cursor: pointer;
    transition: var(--transition);
    font-size: 0.875rem;
}

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

.courses-section {
    padding: 3rem 0;
    background-color: var(--bg-section);
}

.courses-results {
    margin-bottom: 2rem;
    color: var(--text-medium);
}

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

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

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

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

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

/* Course Detail Page */
.course-hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: 4rem 0;
}

.course-hero-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    align-items: center;
}

.course-hero-content h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    line-height: 1.2;
}

.course-hero-meta {
    display: flex;
    gap: 2rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

.course-hero-meta span {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 0.5rem 1rem;
    border-radius: 20px;
    font-size: 0.875rem;
}

.course-hero-description {
    font-size: 1.125rem;
    line-height: 1.6;
    margin-bottom: 2rem;
}

.course-hero-actions .btn {
    margin-right: 1rem;
    margin-bottom: 1rem;
}

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

.course-content {
    padding: 4rem 0;
}

.course-content-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
}

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

.course-main h3 {
    font-size: 1.5rem;
    font-weight: 600;
    margin: 2rem 0 1rem;
    color: var(--text-dark);
}

.course-main ul {
    margin-left: 1.5rem;
    margin-bottom: 2rem;
}

.course-main li {
    margin-bottom: 0.5rem;
    color: var(--text-medium);
}

.curriculum-list {
    list-style: none;
    margin-left: 0;
}

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

.curriculum-item strong {
    color: var(--text-dark);
}

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

.instructor-card {
    text-align: center;
    margin-bottom: 2rem;
}

.instructor-card h4 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.instructor-bio {
    color: var(--text-medium);
    line-height: 1.6;
    font-size: 0.875rem;
}

.faq-section {
    margin-top: 2rem;
}

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

.faq-question {
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
}

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

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

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

    .nav-toggle {
        display: flex;
    }

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

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

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

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

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

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

    .course-sidebar {
        position: static;
    }

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

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

    .search-input {
        min-width: auto;
    }

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

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

@media (max-width: 480px) {
    .container,
    .nav-container,
    .hero-container,
    .footer-container,
    .filters-container,
    .course-hero-container,
    .course-content-container {
        padding: 0 15px;
    }

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

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

    .btn {
        padding: 0.75rem 1.5rem;
        font-size: 0.875rem;
    }

    .course-card {
        margin-bottom: 1rem;
    }

    .feature-card,
    .trust-item {
        padding: 1.5rem;
    }
}