:root {
            --primary-color: #4A90E2;
            --secondary-color: #50E3C2;
            --dark-color: #333;
            --light-color: #f4f4f4;
            --text-color: #555;
            --white-color: #fff;
            --nav-height: 80px;
        }

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

        body {
            font-family: 'Helvetica Neue', Arial, sans-serif;
            line-height: 1.6;
            color: var(--text-color);
            background-color: var(--white-color);
        }

        html {
            scroll-behavior: smooth;
            scroll-padding-top: var(--nav-height); /* Offset for fixed nav */
        }

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

        ul {
            list-style: none;
        }

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

        img {
            max-width: 100%;
            display: block;
        }

        section {
            padding: 80px 0;
        }

        .section-title {
            text-align: center;
            margin-bottom: 60px;
        }

        .section-title h2 {
            font-size: 2.5rem;
            color: var(--dark-color);
            margin-bottom: 10px;
        }

        .section-title p {
            font-size: 1.1rem;
            max-width: 600px;
            margin: 0 auto;
        }

        /* --- Buttons --- */
        .btn {
            display: inline-block;
            padding: 10px 20px;
            border-radius: 5px;
            text-align: center;
            transition: all 0.3s ease;
            font-weight: bold;
        }

        .btn-login {
            background: transparent;
            border: 1px solid var(--primary-color);
            color: var(--primary-color);
        }

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

        .btn-register {
            background: var(--primary-color);
            border: 1px solid var(--primary-color);
            color: var(--white-color);
        }

        .btn-register:hover {
            background: #3a7bc8;
            border-color: #3a7bc8;
        }

        .btn-primary {
            background: var(--primary-color);
            color: var(--white-color);
            padding: 15px 30px;
            font-size: 1.1rem;
            border-radius: 5px;
        }

        .btn-primary:hover {
            background: #3a7bc8;
            transform: translateY(-2px);
        }

        /* --- Navigation --- */
        nav {
            background: var(--white-color);
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            z-index: 1000;
            height: var(--nav-height);
        }

        nav .container {
            height: 100%;
        }
        
        .navbar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            height: 100%;
        }

        .logo {
            font-size: 1.8rem;
            font-weight: bold;
            color: var(--dark-color);
        }

        .logo i {
            color: var(--primary-color);
            margin-right: 8px;
        }

        .nav-links {
            display: flex;
            align-items: center;
        }

        .nav-links li {
            margin: 0 15px;
        }

        .nav-links a {
            color: var(--text-color);
            font-weight: 500;
            transition: color 0.3s ease;
        }

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

        .auth-buttons {
            display: flex;
            gap: 10px;
        }
        
        .mobile-nav-toggle {
            display: none; /* Hidden on desktop */
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--dark-color);
        }

        /* --- Hero Section --- */
        .hero {
            background-color: #f9faff;
            padding-top: calc(var(--nav-height) + 60px); /* Adjust padding for fixed nav */
            padding-bottom: 60px;
        }

        .hero-content {
            display: grid;
            grid-template-columns: 1fr 1fr;
            align-items: center;
            gap: 40px;
        }

        .hero-text h1 {
            font-size: 3.2rem;
            line-height: 1.2;
            color: var(--dark-color);
            margin-bottom: 20px;
        }

        .hero-text p {
            font-size: 1.2rem;
            margin-bottom: 30px;
        }

        .hero-image img {
            border-radius: 10px;
            box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        }
        
        /* --- Features Section --- */
        .features {
            background-color: var(--white-color);
        }

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

        .feature-card {
            background: #fdfdfd;
            padding: 40px;
            text-align: center;
            border: 1px solid #eee;
            border-radius: 10px;
            transition: all 0.5s ease;
            opacity: 0;
            transform: translateY(20px);
        }
        
        .feature-card.visible {
            opacity: 1;
            transform: translateY(0);
        }

        .feature-icon {
            font-size: 3rem;
            color: var(--primary-color);
            margin-bottom: 20px;
        }

        .feature-card h3 {
            font-size: 1.5rem;
            color: var(--dark-color);
            margin-bottom: 10px;
        }

        /* --- Courses Section --- */
        .courses {
            background-color: var(--light-color);
        }

        .courses-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 30px;
        }

        .course-card {
            background: var(--white-color);
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        
        .course-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        }

        .course-image img {
            width: 100%;
            height: 200px;
            object-fit: cover;
        }
        
        .course-content {
            padding: 20px;
        }

        .course-category {
            display: inline-block;
            background-color: var(--secondary-color);
            color: var(--dark-color);
            padding: 5px 10px;
            border-radius: 5px;
            font-size: 0.8rem;
            font-weight: bold;
            margin-bottom: 15px;
        }

        .course-content h3 {
            font-size: 1.3rem;
            margin-bottom: 15px;
            color: var(--dark-color);
        }
        
        .course-meta {
            display: flex;
            justify-content: space-between;
            align-items: center;
            font-size: 0.9rem;
            color: #777;
            border-top: 1px solid #eee;
            padding-top: 15px;
        }

        .course-meta span i {
            margin-right: 5px;
            color: var(--primary-color);
        }

        /* --- Dashboard Specific Styles --- */
        .dashboard-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 30px;
        }
        
        .search-filter {
            display: flex;
            gap: 15px;
        }
        
        .search-filter input {
            padding: 10px 15px;
            border: 1px solid #ddd;
            border-radius: 5px;
            width: 250px;
        }
        
        .search-filter select {
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: 5px;
        }
        
        .progress-indicator {
            height: 5px;
            background-color: #eee;
            margin-bottom: 20px;
            border-radius: 5px;
            overflow: hidden;
        }
        
        .progress-bar {
            height: 100%;
            background-color: var(--primary-color);
            width: 65%; /* Example progress */
        }
        
        .course-actions {
            display: flex;
            justify-content: space-between;
            margin-top: 20px;
        }
        
        .btn-enroll {
            background: var(--secondary-color);
            color: var(--dark-color);
            border: none;
        }
        
        .btn-enroll:hover {
            background: #3dc7ad;
        }
        
        .btn-view {
            background: transparent;
            border: 1px solid var(--primary-color);
            color: var(--primary-color);
        }
        
        .btn-view:hover {
            background: var(--primary-color);
            color: white;
        }

        /* --- Footer --- */
        footer {
            background-color: var(--dark-color);
            color: #ccc;
            padding: 60px 0 20px;
        }
        
        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }
        
        .footer-column h3 {
            color: var(--white-color);
            margin-bottom: 20px;
            font-size: 1.2rem;
        }

        .footer-column p {
            margin-bottom: 10px;
            line-height: 1.8;
        }

        .footer-column i {
            margin-right: 10px;
            color: var(--primary-color);
        }

        .social-links a {
            color: #ccc;
            font-size: 1.5rem;
            margin-right: 15px;
            transition: color 0.3s ease;
        }
        
        .social-links a:hover {
            color: var(--secondary-color);
        }

        .footer-links li {
            margin-bottom: 10px;
        }

        .footer-links a {
            color: #ccc;
            transition: color 0.3s ease;
        }

        .footer-links a:hover {
            color: var(--white-color);
            padding-left: 5px;
        }
        
        .footer-bottom {
            text-align: center;
            border-top: 1px solid #444;
            padding-top: 20px;
            font-size: 0.9rem;
        }

        /* --- Responsive Design (Media Queries) --- */

        /* Tablets */
        @media (max-width: 992px) {
            .hero-content {
                grid-template-columns: 1fr;
                text-align: center;
            }

            .hero-image {
                grid-row: 1; /* Move image to the top on smaller screens */
                margin-bottom: 40px;
            }
            
            .hero-text h1 {
                font-size: 2.8rem;
            }
            
            .dashboard-header {
                flex-direction: column;
                align-items: flex-start;
                gap: 20px;
            }
            
            .search-filter {
                width: 100%;
            }
            
            .search-filter input {
                width: 100%;
            }
        }
        
        /* Mobile */
        @media (max-width: 768px) {
            .section-title h2 {
                font-size: 2rem;
            }

            .auth-buttons {
                display: none; /* Hide buttons in nav, could move them inside menu */
            }

            .nav-links {
                position: absolute;
                top: var(--nav-height);
                left: 0;
                width: 100%;
                background: var(--white-color);
                flex-direction: column;
                align-items: center;
                box-shadow: 0 5px 10px rgba(0,0,0,0.1);
                max-height: 0;
                overflow: hidden;
                transition: max-height 0.5s ease-out;
            }

            .nav-links.active {
                max-height: 500px; /* An arbitrary large height */
            }

            .nav-links li {
                width: 100%;
                text-align: center;
            }
            
            .nav-links a {
                display: block;
                padding: 15px 0;
                border-bottom: 1px solid var(--light-color);
                width: 100%;
            }

            .mobile-nav-toggle {
                display: block; /* Show hamburger icon */
            }
            
            .mobile-nav-toggle.active .fa-bars {
                display: none;
            }

            .mobile-nav-toggle:not(.active) .fa-times {
                display: none;
            }
            
            .footer-content {
                grid-template-columns: 1fr;
                text-align: center;
            }
            .social-links {
                justify-content: center;
                display: flex;
            }
            
            .course-actions {
                flex-direction: column;
                gap: 10px;
            }
            
            .course-actions .btn {
                width: 100%;
                text-align: center;
            }
        }