* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background-color: #f5f7fa;
            color: #333;
            line-height: 1.6;
        }
        
        .container {
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
        }
        
        /* Course Card Styles */
        .course-card {
            background: #fff;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
            overflow: hidden;
            margin: 20px auto;
            max-width: 800px;
            display: flex;
            transition: transform 0.3s ease;
        }
        
        .course-card:hover {
            transform: translateY(-5px);
        }
        
        .course-image {
            flex: 1;
        }
        
        .course-image img {
            width: 100%;
            height: 100%;
            object-fit: cover;
        }
        
        .course-content {
            flex: 2;
            padding: 25px;
        }
        
        .course-category {
            display: inline-block;
            background: #4e54c8;
            color: white;
            padding: 5px 10px;
            border-radius: 20px;
            font-size: 12px;
            margin-bottom: 10px;
        }
        
        .course-content h3 {
            font-size: 22px;
            margin-bottom: 15px;
            color: #2c3e50;
        }
        
        .course-content p {
            color: #7f8c8d;
            margin-bottom: 20px;
        }
        
        .progress-indicator {
            background: #ecf0f1;
            border-radius: 5px;
            height: 8px;
            margin-bottom: 20px;
        }
        
        .progress-bar {
            background: #4e54c8;
            height: 100%;
            border-radius: 5px;
        }
        
        .course-meta {
            display: flex;
            margin-bottom: 20px;
        }
        
        .course-meta span {
            margin-right: 20px;
            color: #7f8c8d;
            font-size: 14px;
        }
        
        .course-meta i {
            margin-right: 5px;
        }
        
        .btn {
            display: inline-block;
            padding: 10px 20px;
            border-radius: 5px;
            text-decoration: none;
            font-weight: 500;
            transition: all 0.3s ease;
        }
        
        .btn-enroll {
            background: #4e54c8;
            color: white;
            margin-right: 10px;
        }
        
        .btn-enroll:hover {
            background: #3a41b5;
        }
        
        .btn-view {
            background: transparent;
            color: #4e54c8;
            border: 1px solid #4e54c8;
        }
        
        .btn-view:hover {
            background: #4e54c8;
            color: white;
        }
        
        /* Course Details Page Styles (hidden by default) */
        .course-details {
            display: none;
            max-width: 1000px;
            margin: 30px auto;
            background: white;
            border-radius: 10px;
            box-shadow: 0 5px 25px rgba(0, 0, 0, 0.1);
            overflow: hidden;
        }
        
        .course-details.active {
            display: block;
        }
        
        .course-header {
            position: relative;
            height: 300px;
            overflow: hidden;
        }
        
        .course-header img {
            width: 100%;
            height: 100%;
            object-fit: cover;
        }
        
        .course-header-content {
            position: absolute;
            bottom: 0;
            left: 0;
            right: 0;
            padding: 30px;
            background: linear-gradient(transparent, rgba(0, 0, 0, 0.8));
            color: white;
        }
        
        .course-header-content h1 {
            font-size: 32px;
            margin-bottom: 10px;
        }
        
        .course-header-content p {
            opacity: 0.9;
            max-width: 600px;
        }
        
        .course-body {
            padding: 30px;
            display: flex;
        }
        
        .course-main {
            flex: 2;
            padding-right: 30px;
        }
        
        .course-sidebar {
            flex: 1;
        }
        
        .course-section {
            margin-bottom: 30px;
        }
        
        .course-section h2 {
            font-size: 24px;
            margin-bottom: 15px;
            color: #2c3e50;
            border-bottom: 2px solid #f1f1f1;
            padding-bottom: 10px;
        }
        
        .course-section h3 {
            font-size: 18px;
            margin: 15px 0 10px;
            color: #4e54c8;
        }
        
        .course-section ul {
            margin-left: 20px;
            margin-bottom: 15px;
        }
        
        .course-section p {
            margin-bottom: 15px;
        }
        
        .price-box {
            background: #f9f9f9;
            padding: 20px;
            border-radius: 8px;
            text-align: center;
            margin-bottom: 20px;
        }
        
        .price {
            font-size: 36px;
            font-weight: bold;
            color: #4e54c8;
            margin: 10px 0;
        }
        
        .price span {
            font-size: 16px;
            color: #7f8c8d;
            font-weight: normal;
            text-decoration: line-through;
            display: block;
        }
        
        .btn-buy {
            background: #4e54c8;
            color: white;
            width: 100%;
            padding: 15px;
            font-size: 16px;
            border: none;
            border-radius: 5px;
            cursor: pointer;
            transition: background 0.3s;
        }
        
        .btn-buy:hover {
            background: #3a41b5;
        }
        
        .instructor {
            display: flex;
            align-items: center;
            margin-top: 20px;
        }
        
        .instructor img {
            width: 60px;
            height: 60px;
            border-radius: 50%;
            margin-right: 15px;
            object-fit: cover;
        }
        
        .instructor-info h4 {
            margin-bottom: 5px;
        }
        
        .instructor-info p {
            color: #7f8c8d;
            font-size: 14px;
        }
        
        .course-features {
            list-style: none;
            margin-left: 0;
        }
        
        .course-features li {
            padding: 10px 0;
            border-bottom: 1px solid #eee;
            display: flex;
            justify-content: space-between;
        }
        
        .course-features li:last-child {
            border-bottom: none;
        }
        
        .feature-label {
            color: #7f8c8d;
        }
        
        .feature-value {
            font-weight: 500;
        }
        
        .back-btn {
            display: inline-block;
            margin-bottom: 20px;
            color: #4e54c8;
            text-decoration: none;
            font-weight: 500;
        }
        
        .back-btn i {
            margin-right: 5px;
        }