:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --light-color: #ecf0f1;
    --dark-color: #2c3e50;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    --text-color: #333;
    --text-light: #7f8c8d;
    --shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    --border-radius: 4px;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: #f9f9f9;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.main-content {
    flex: 1;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

a {
    text-decoration: none;
    color: var(--secondary-color);
}

img {
    max-width: 100%;
    height: auto;
}

.header {
    background-color: var(--primary-color);
    color: white;
    padding: 4px 0;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

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

.logo a {
    display: flex;
    align-items: center;
}

.logo-link {
    display: inline-flex;
    align-items: center;
    padding: 15px 0;
    margin: 0;
}

.logo-image {
    width: 100%;
    height: auto;
    max-width: 200px;
    min-width: 80px;
    max-height: 40px;
}

.nav {
    display: flex;
    gap: 20px;
}

.nav-link {
    color: white;
    font-weight: 500;
    transition: color 0.3s;
}

.nav-link:hover {
    color: var(--light-color);
}

.search-container {
    flex-grow: 1;
    max-width: 400px;
    margin-left: 20px;
}

.search-form {
    display: flex;
    gap: 0;
}

.search-input {
    flex-grow: 1;
    padding: 4px 10px;
    border: none;
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    font-size: 0.9rem;
}

.search-button {
    padding: 4px 10px;
    background-color: var(--secondary-color);
    color: white;
    border: none;
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    cursor: pointer;
    transition: background-color 0.3s;
    font-size: 0.9rem;
}

.search-button:hover {
    background-color: #2980b9;
}

.hero {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 80px 0;
    text-align: center;
}

.hero-content {
    max-width: 800px;
    margin: 0 auto;
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 20px;
}

.hero-subtitle {
    font-size: 1.3rem;
    margin-bottom: 30px;
    opacity: 0.9;
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.btn {
    display: inline-block;
    padding: 10px 20px;
    border-radius: var(--border-radius);
    font-weight: 500;
    text-align: center;
    transition: all 0.3s;
    cursor: pointer;
    border: none;
    font-size: 1rem;
}

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

.btn-primary:hover {
    background-color: #2980b9;
    transform: translateY(-2px);
}

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

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

.btn-sm {
    padding: 8px 15px;
    font-size: 0.9rem;
}

.courses-section {
    padding: 60px 0;
    background-color: white;
}

.courses-section h2 {
    text-align: center;
    margin-bottom: 20px;
    font-size: 2rem;
    color: var(--primary-color);
}

.section-description {
    text-align: center;
    margin-bottom: 40px;
    color: var(--text-light);
    max-width: 700px;
    margin-left: auto;
    margin-right: auto;
}

.course-categories {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
}

.category-block {
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

.category-block:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.category-header {
    background-color: var(--primary-color);
    color: white;
    padding: 20px;
    display: flex;
    align-items: center;
    gap: 15px;
}

.category-icon {
    color: var(--light-color);
}

.category-header h3 {
    flex-grow: 1;
    margin: 0;
}

.course-count {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 5px 10px;
    border-radius: 20px;
    font-size: 0.8rem;
}

.category-courses {
    padding: 20px;
}

.course-preview {
    margin-bottom: 15px;
    padding-bottom: 15px;
    border-bottom: 1px solid #eee;
}

.course-preview:last-child {
    margin-bottom: 0;
    padding-bottom: 0;
    border-bottom: none;
}

.course-preview h4 {
    margin-bottom: 8px;
    color: var(--primary-color);
}

.course-preview h4 a {
    color: var(--primary-color);
}

.course-preview h4 a:hover {
    color: var(--secondary-color);
}

.category-footer {
    padding: 15px 20px;
    background-color: #f8f9fa;
    text-align: right;
}

.category-header {
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 30px;
    padding-bottom: 20px;
    border-bottom: 2px solid #eee;
}

.category-icon {
    color: var(--secondary-color);
}

.category-header h1 {
    margin: 0;
    color: var(--primary-color);
}

.category-description {
    color: var(--text-light);
    margin-left: auto;
}

.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
}

.course-card {
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
}

.course-card-header {
    padding: 20px;
    background-color: var(--primary-color);
    color: white;
}

.course-card-header h3 {
    margin: 0;
    font-size: 1.2rem;
}

.course-card-header h3 a {
    color: white;
}

.course-card-header h3 a:hover {
    color: var(--light-color);
}

.course-card-body {
    padding: 20px;
}

.course-card-footer {
    padding: 15px 20px;
    background-color: #f8f9fa;
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

.course-container {
    background-color: white;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    overflow: hidden;
}

.course-header {
    padding: 30px;
    background-color: var(--primary-color);
    color: white;
}

.course-breadcrumb {
    margin-bottom: 15px;
    opacity: 0.8;
    font-size: 0.9rem;
}

.course-breadcrumb a {
    color: var(--light-color);
}

.course-breadcrumb a:hover {
    color: white;
}

.course-header h1 {
    margin: 0 0 15px 0;
    font-size: 2rem;
}

.course-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.course-category {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1rem;
}

.course-content {
    padding: 30px;
}

.course-content h1,
.course-content h2,
.course-content h3,
.course-content h4,
.course-content h5,
.course-content h6 {
    margin: 25px 0 15px 0;
    color: var(--primary-color);
}

.course-content h1 { font-size: 2rem; }
.course-content h2 { font-size: 1.8rem; }
.course-content h3 { font-size: 1.6rem; }
.course-content h4 { font-size: 1.4rem; }
.course-content h5 { font-size: 1.2rem; }
.course-content h6 { font-size: 1rem; }

.course-content p {
    margin-bottom: 15px;
}

.course-content ul,
.course-content ol {
    margin-bottom: 20px;
    padding-left: 20px;
}

.course-content li {
    margin-bottom: 8px;
}

.course-content pre {
    background-color: #f5f5f5;
    padding: 15px;
    border-radius: var(--border-radius);
    overflow-x: auto;
    margin-bottom: 20px;
    font-family: 'Courier New', Courier, monospace;
}

.course-content code {
    background-color: #f5f5f5;
    padding: 2px 5px;
    border-radius: var(--border-radius);
    font-family: 'Courier New', Courier, monospace;
}

.course-content blockquote {
    border-left: 4px solid var(--secondary-color);
    padding-left: 15px;
    margin-left: 0;
    color: var(--text-light);
    font-style: italic;
}

.course-footer {
    padding: 20px 30px;
    background-color: #f8f9fa;
    border-top: 1px solid #eee;
}

.course-actions {
    display: flex;
    justify-content: space-between;
    gap: 15px;
    flex-wrap: wrap;
}

.search-container {
    margin-bottom: 40px;
}

.search-container h1 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.search-input-group {
    display: flex;
    gap: 0;
    margin-bottom: 20px;
}

.search-input {
    flex-grow: 1;
    padding: 12px 15px;
    border: 1px solid #ddd;
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    font-size: 1rem;
}

.search-filters {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.filter-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.filter-select {
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: var(--border-radius);
    font-size: 1rem;
    min-width: 150px;
}

.results-header {
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.results-header h2 {
    margin: 0;
    color: var(--primary-color);
}

.course-category-badge {
    display: inline-flex;
    align-items: center;
    gap: 5px;
    background-color: #f0f8ff;
    color: var(--secondary-color);
    padding: 3px 8px;
    border-radius: 20px;
    font-size: 0.8rem;
    margin-left: 10px;
}

.no-courses,
.no-results {
    text-align: center;
    padding: 60px 0;
    color: var(--text-light);
}

.no-results i {
    margin-bottom: 20px;
    color: var(--secondary-color);
}

.error-container {
    text-align: center;
    padding: 80px 0;
}

.error-content {
    max-width: 600px;
    margin: 0 auto;
}

.error-icon {
    color: var(--danger-color);
    margin-bottom: 20px;
}

.error-content h1 {
    margin-bottom: 20px;
    color: var(--primary-color);
}

.error-content p {
    margin-bottom: 30px;
    font-size: 1.1rem;
}

.error-actions {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.footer {
    background-color: var(--dark-color);
    color: white;
    padding: 20px 0;
    margin-top: auto;
}

.footer-bottom {
    text-align: center;
    padding: 20px 0;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--light-color);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    .header .container {
        flex-direction: column;
        gap: 15px;
    }

    .search-container {
        max-width: 100%;
        margin-left: 0;
    }

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

    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .category-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }

    .course-meta {
        flex-direction: column;
        align-items: flex-start;
        gap: 10px;
    }

    .course-actions {
        flex-direction: column;
    }

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

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

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

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

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

.mt-1 { margin-top: 5px; }
.mt-2 { margin-top: 10px; }
.mt-3 { margin-top: 15px; }
.mt-4 { margin-top: 20px; }
.mt-5 { margin-top: 30px; }

.mb-1 { margin-bottom: 5px; }
.mb-2 { margin-bottom: 10px; }
.mb-3 { margin-bottom: 15px; }
.mb-4 { margin-bottom: 20px; }
.mb-5 { margin-bottom: 30px; }

.pt-1 { padding-top: 5px; }
.pt-2 { padding-top: 10px; }
.pt-3 { padding-top: 15px; }
.pt-4 { padding-top: 20px; }
.pt-5 { padding-top: 30px; }

.pb-1 { padding-bottom: 5px; }
.pb-2 { padding-bottom: 10px; }
.pb-3 { padding-bottom: 15px; }
.pb-4 { padding-bottom: 20px; }
.pb-5 { padding-bottom: 30px; }