:root {
            --primary-color: #3a86ff;
            --secondary-color: #ff006e;
            --dark-color: #1a1a2e;
            --light-color: #f8f9fa;
            --success-color: #38b000;
            --warning-color: #ffbe0b;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            margin: 0;
            padding: 0;
            background-color: #1a222e;
            color: #333;
        }
        
        .container {
            max-width: 100%;
            margin: 0 auto;
            padding: 20px;
        }
        
        header {
            background: linear-gradient(135deg, var(--primary-color), var(--dark-color));
            color: white;
            padding: 15px 0;
            box-shadow: 0 4px 12px rgba(0,0,0,0.1);
            position: relative;
        }
        
        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        .logo {
            font-size: 24px;
            font-weight: bold;
            text-decoration: none;
            color: white;
            display: flex;
            align-items: center;
        }
        
        .logo i {
            margin-right: 10px;
            font-size: 28px;
        }
        
        /* Navigation links */
        .nav-links {
            display: flex;
            background-color: #35445c;
            padding: 10px 0;
            box-shadow: 0 2px 8px rgba(0,0,0,0.1);
        }
        
        .nav-links .container {
            display: flex;
            justify-content: center;
            gap: 30px;
            padding: 0 20px;
        }
        
        .nav-links a {
            text-decoration: none;
            color: #ffffff;
            font-weight: 500;
            padding: 8px 15px;
            border-radius: 4px;
            transition: all 0.3s ease;
        }
        
        .nav-links a:hover {
            color: #000000;
            background-color: rgb(255 231 58);
        }
        
        .nav-links a.active {
            color: var(--primary-color);
            background-color: rgba(58, 134, 255, 0.1);
        }
        
        .lesson-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
            gap: 25px;
            margin-top: 30px;
        }
        
        .lesson-card {
            background-color: #424a71;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 3px 10px rgba(0,0,0,0.1);
            transition: all 0.3s ease;
            cursor: pointer;
            position: relative;
        }
        
        .lesson-card:hover {
            transform: translateY(-8px);
            box-shadow: 0 10px 20px rgba(0,0,0,0.15);
        }
        
        .lesson-card img {
            width: 100%;
            height: 160px;
            object-fit: cover;
            transition: transform 0.5s ease;
        }
        
        .lesson-card:hover img {
            transform: scale(1.05);
        }
        
        .lesson-info {
            padding: 15px;
            text-align: center;
        }
        
        .lesson-title {
            font-weight: bold;
            margin-bottom: 5px;
            color: #afafff;
            font-size: 16px;
        }
        
        .lesson-container {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: #262626;
            z-index: 1000;
            overflow-y: auto;
        }
        
        .lesson-layout {
            max-width: 1200px;
            margin: 0 auto;
            padding: 20px;
        }
        
        .lesson-main {
            width: 100%;
        }
        
        .xa-space {
            width: 970px;
            height: 250px;
            max-width: 100%;
            margin: 0 auto 20px;
            display: flex;
            justify-content: center;
            align-items: center;
            font-size: 18px;
            color: #888;
            border-radius: 8px;
        }
        
        .lesson-iframe-container {
            width: 100%;
            height: 80vh;
            position: relative;
            background-color: #262626;
            margin-bottom: 20px; /* Changed to 0 to position ad right below */
            border-radius: 12px;
            overflow: hidden;
        }
        
        .lesson-iframe {
            width: 100%;
            height: 100%;
            border: none;
            display: none;
        }
        
        .play-button-container {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            display: flex;
            justify-content: center;
            align-items: center;
            background-color: rgb(46 51 80);
            cursor: pointer;
        }
        
        .play-button {
            width: 120px;
            height: 120px;
            background-color: rgb(26 213 56 / 61%);
            border-radius: 50%;
            display: flex;
            justify-content: center;
            align-items: center;
            transition: all 0.4s ease;
            box-shadow: 0 0 30px rgb(0 0 0 / 0%);
        }
        
        .play-button:hover {
            transform: scale(1.1);
            background-color: rgb(59 197 31 / 94%);
            box-shadow: 0 0 40px rgb(38 255 6 / 80%);
        }
        
        .play-button::before {
            content: '';
            width: 0;
            height: 0;
            border-top: 30px solid transparent;
            border-left: 50px solid white;
            border-bottom: 30px solid transparent;
            margin-left: 12px;
        }
        
        .close-button {
            position: fixed;
            top: 20px;
            right: 30px;
            color: white;
            font-size: 50px;
            cursor: pointer;
            z-index: 1001;
            transition: all 0.3s ease;
            width: 50px;
            height: 50px;
            vertical-align: middle;
            border-radius: 50%;
            background-color: rgb(255 69 69);
            padding: 0;
            margin: 0;
            text-align: center;
            line-height: 40px;
        }
        
        .close-button:hover {
            background-color: rgb(0 0 0);
            transform: rotate(90deg);
        }
        
        .search-box {
            margin: 30px 0;
            text-align: center;
        }
        
        .search-box input {
            padding: 12px 20px;
            width: 400px;
            max-width: 100%;
            border-radius: 30px;
            border: 1px solid #ddd;
            font-size: 16px;
            outline: none;
            box-shadow: 0 2px 10px rgba(0,0,0,0.05);
            transition: all 0.3s ease;
            background-color: white;
            background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='%23888' viewBox='0 0 16 16'%3E%3Cpath d='M11.742 10.344a6.5 6.5 0 1 0-1.397 1.398h-.001c.03.04.062.078.098.115l3.85 3.85a1 1 0 0 0 1.415-1.414l-3.85-3.85a1.007 1.007 0 0 0-.115-.1zM12 6.5a5.5 5.5 0 1 1-11 0 5.5 5.5 0 0 1 11 0z'%3E%3C/path%3E%3C/svg%3E");
            background-repeat: no-repeat;
            background-position: 15px center;
            padding-left: 45px;
        }
        
        .search-box input:focus {
            border-color: var(--primary-color);
            box-shadow: 0 2px 15px rgba(58, 134, 255, 0.2);
        }
        
        #lessonTitle {
            color: white;
            margin: 0 0 20px 0;
            text-align: center;
            font-size: 32px;
            font-weight: 600;
            text-shadow: 0 2px 5px rgba(0,0,0,0.3);
        }
        
        .lesson-thumbnail {
            width: 200px;
            margin: 0 auto;
            height: 200px;
            transition: transform 0.5s ease;
            text-align: center;
            display: grid;
            margin-top: 40px;
            border-radius: 10px;
        }
        
        /* Article section */
        .article-section {
            background-color: white;
            border-radius: 12px;
            padding: 30px;
            margin-top: 40px;
            box-shadow: 0 3px 15px rgba(0,0,0,0.1);
        }
        
        .article-section h2 {
            font-size: 28px;
            color: var(--dark-color);
            margin-bottom: 20px;
            padding-bottom: 15px;
            border-bottom: 2px solid #f0f2f5;
        }
        
        .article-content {
            line-height: 1.7;
            color: #444;
            font-size: 16px;
        }
        
        .article-content p {
            margin-bottom: 15px;
        }
        
        /* Lesson details section */
        .lesson-details {
            background-color: rgba(255, 255, 255, 0.05);
            padding: 20px;
            border-radius: 10px;
            margin-top: 20px;
            color: white;
        }
        
        .lesson-description {
            line-height: 1.6;
            margin-bottom: 20px;
        }
        
        /* Recommended lessons */
        .recommended-lessons {
            margin-top: 40px;
        }
        
        .recommended-lessons h3 {
            color: white;
            font-size: 24px;
            margin-bottom: 20px;
        }
        
        .recommended-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
            gap: 20px;
        }
        
        /* Responsive adjustments */
        @media (max-width: 768px) {
            .nav-links .container {
                gap: 10px;
            }
            
            .nav-links a {
                padding: 8px 10px;
                font-size: 14px;
            }
            
            .search-box input {
                width: 90%;
            }
            
            .lesson-grid {
                grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
            }
            
            .recommended-grid {
                grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
            }
        }
		
		
		
		        /* Fullscreen button styles */
        .fullscreen-button {
            position: absolute;
            top: 10px;
            right: 10px;
            background-color: rgba(0, 0, 0, 0.5);
            color: white;
            border: none;
            border-radius: 4px;
            padding: 5px 10px;
            cursor: pointer;
            z-index: 10;
            display: none; /* Hidden by default */
        }
        
        .fullscreen-button:hover {
            background-color: rgba(0, 0, 0, 0.7);
        }
        
        /* Ensure iframe covers the container when in fullscreen mode */
        .lesson-iframe-container.fullscreen .lesson-iframe {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: 9999;
        }