/* ==================== GLOBAL STYLES ==================== */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: Arial, sans-serif;
            line-height: 1.6;
            color: #333;
            background-color: #f4f4f4;
        }
        
        /* ==================== MOBILE-FIRST BASE STYLES ==================== */
        
        /* ==================== HEADER SECTION (MOBILE) ==================== */
        header {
            background-color: #2563eb;
            color: white;
            padding: 1rem 0;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            position: relative;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        nav {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
        }
        
        .logo {
            font-size: 1.5rem;
            font-weight: bold;
        }
        
        /* Hamburger Menu Button */
        .hamburger {
            display: block;
            background: none;
            border: none;
            cursor: pointer;
            padding: 5px;
        }
        
        .hamburger span {
            display: block;
            width: 25px;
            height: 3px;
            background-color: white;
            margin: 5px 0;
            transition: 0.3s;
        }
        
        /* Navigation menu - hidden by default on mobile */
        nav ul {
            list-style: none;
            display: none;
            flex-direction: column;
            width: 100%;
            text-align: center;
            padding: 1rem 0;
        }
        
        nav ul.active {
            display: flex;
        }
        
        nav ul li {
            width: 100%;
            padding: 0.5rem 0;
        }
        
        nav a {
            color: white;
            text-decoration: none;
            font-weight: 500;
            display: block;
            padding: 0.5rem;
            transition: background-color 0.3s;
        }
        
        nav a:hover {
            background-color: rgba(255, 255, 255, 0.1);
        }
        
        nav a.active {
            border-bottom: 2px solid white;
            padding-bottom: 5px;
        }
        
        /* ==================== PAGE HEADER ==================== */
        /* Banner for internal pages */
        .page-header {
            background: linear-gradient(135deg, #2563eb 0%, #1e40af 100%);
            color: white;
            padding: 3rem 0;
            text-align: center;
        }
        
        .page-header h1 {
            font-size: 2.5rem;
            margin-bottom: 0.5rem;
        }
        
        .page-header p {
            font-size: 1.1rem;
        }
        
        /* ==================== MAIN CONTENT AREA ==================== */
        main {
            padding: 3rem 0;
        }
        
        /* ==================== COURSE CATEGORIES SECTION ==================== */
        .categories {
            margin-bottom: 3rem;
        }
        
        .section-title {
            font-size: 2rem;
            color: #2563eb;
            margin-bottom: 1.5rem;
        }
        
        /* Grid for category cards - 2 columns */
        .categories-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 1.5rem;
            margin-bottom: 3rem;
        }
        
        /* Individual category card */
        .category-card {
            background-color: white;
            padding: 2rem;
            border-radius: 8px;
            text-align: center;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            transition: transform 0.3s, box-shadow 0.3s;
            cursor: pointer;
        }
        
        .category-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 5px 15px rgba(0,0,0,0.15);
        }
        
        .category-icon {
            font-size: 3rem;
            margin-bottom: 1rem;
        }
        
        .category-card h3 {
            color: #1e40af;
            margin-bottom: 0.5rem;
        }
        
        .category-card p {
            color: #666;
            font-size: 0.9rem;
        }
        
        /* ==================== ALL COURSES SECTION ==================== */
        .all-courses {
            background-color: white;
            padding: 2rem;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }
        
        /* List of courses - each course is a row */
        .course-list {
            display: flex;
            flex-direction: column;
            gap: 1.5rem;
            margin-top: 1.5rem;
        }
        
        /* Individual course item - horizontal layout */
        .course-item {
            display: flex;
            background-color: #f9fafb;
            border-radius: 8px;
            overflow: hidden;
            transition: transform 0.3s, box-shadow 0.3s;
        }
        
        .course-item:hover {
            transform: translateX(5px);
            box-shadow: 0 3px 10px rgba(0,0,0,0.1);
        }
        
        /* Course thumbnail - smaller on mobile */
        .course-thumbnail {
            background-color: #dbeafe;
            width: 80px;
            min-height: 80px;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 2rem;
            flex-shrink: 0;
        }
        
        /* Course details on the right */
        .course-details {
            padding: 1.5rem;
            flex-grow: 1;
        }
        
        .course-details h3 {
            color: #1e40af;
            margin-bottom: 0.5rem;
            font-size: 1.1rem;
        }
        
        .course-details p {
            color: #666;
            margin-bottom: 0.8rem;
            font-size: 0.9rem;
        }
        
        /* Course metadata - stack on mobile */
        .course-meta {
            display: flex;
            flex-direction: column;
            gap: 0.5rem;
            font-size: 0.85rem;
            color: #666;
        }
        
        .course-meta span {
            display: flex;
            align-items: center;
            gap: 0.3rem;
        }
        
        /* Enroll button */
        .enroll-button {
            display: inline-block;
            background-color: #2563eb;
            color: white;
            padding: 8px 20px;
            border-radius: 5px;
            text-decoration: none;
            margin-top: 1rem;
            transition: background-color 0.3s;
        }
        
        .enroll-button:hover {
            background-color: #1e40af;
        }
        
        /* ==================== FOOTER SECTION ==================== */
        footer {
            background-color: #1e293b;
            color: white;
            padding: 2rem 0;
            text-align: center;
            margin-top: 3rem;
        }
        
        footer p {
            margin-bottom: 0.5rem;
        }
        
        .footer-links {
            margin-top: 1rem;
        }
        
        .footer-links a {
            color: #93c5fd;
            text-decoration: none;
            margin: 0 1rem;
        }
        
        .footer-links a:hover {
            color: white;
        }
        
        /* ==================== MEDIA QUERIES FOR LARGER SCREENS ==================== */
        
        /* Tablets and above (768px and up) */
        @media (min-width: 768px) {
            .logo {
                font-size: 1.8rem;
            }
            
            .hamburger {
                display: none;
            }
            
            nav ul {
                display: flex !important;
                flex-direction: row;
                width: auto;
                gap: 2rem;
                padding: 0;
            }
            
            nav ul li {
                width: auto;
                padding: 0;
            }
            
            nav a:hover {
                color: #dbeafe;
                background-color: transparent;
            }
            
            .page-header {
                padding: 2.5rem 0;
            }
            
            .page-header h1 {
                font-size: 2.2rem;
            }
            
            .section-title {
                font-size: 1.8rem;
            }
            
            /* Categories grid - 2 columns on tablets */
            .categories-grid {
                grid-template-columns: repeat(4, 1fr);
                gap: 1.2rem;
            }
            
            /* Course thumbnail larger on tablets */
            .course-thumbnail {
                width: 150px;
                min-height: 120px;
                font-size: 2.5rem;
            }
            
            .course-details h3 {
                font-size: 1.2rem;
            }
            
            /* Course metadata - horizontal on tablets */
            .course-meta {
                flex-direction: row;
                gap: 1.5rem;
                font-size: 0.9rem;
            }
        }
        
        /* Desktop and above (1024px and up) */
        @media (min-width: 1024px) {
            .page-header {
                padding: 3rem 0;
            }
            
            .page-header h1 {
                font-size: 2.5rem;
            }
            
            .page-header p {
                font-size: 1.1rem;
            }
            
            main {
                padding: 3rem 0;
            }
            
            .categories {
                margin-bottom: 3rem;
            }
            
            .section-title {
                font-size: 2rem;
                margin-bottom: 1.5rem;
            }
            
            /* Categories grid - 4 columns on desktop */
            .categories-grid {
                grid-template-columns: repeat(4, 1fr);
                gap: 1.5rem;
                margin-bottom: 3rem;
            }
            
            /* Course thumbnail full size on desktop */
            .course-thumbnail {
                width: 200px;
                font-size: 3rem;
            }
            
            .course-details h3 {
                font-size: 1.3rem;
            }
            
            .course-details p {
                margin-bottom: 1rem;
            }
            
            .course-meta {
                gap: 2rem;
            }
        }