/* Lock Icon Styles */
        .lesson-card.locked {
            position: relative;
            opacity: 0.7;
            cursor: pointer;
        }
        
        .lesson-card.locked::before {
            content: '\f023';
            font-family: 'Font Awesome 6 Free';
            font-weight: 900;
            position: absolute;
            top: 10px;
            right: 10px;
            font-size: 20px;
            color: #ff6b6b;
            z-index: 2;
            animation: lockPulse 2s infinite;
        }
        
        @keyframes lockPulse {
            0%, 100% { opacity: 1; }
            50% { opacity: 0.6; }
        }
        
        .lesson-card.locked:hover {
            transform: translateY(-5px);
            box-shadow: 0 10px 30px rgba(255, 107, 107, 0.3);
        }
        
        /* Modern Modal Styles */
        .lock-modal-overlay {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.7);
            backdrop-filter: blur(10px);
            z-index: 9999;
            animation: fadeIn 0.3s ease;
        }
        
        .lock-modal-overlay.active {
            display: flex;
            justify-content: center;
            align-items: center;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }
        
        .lock-modal {
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border-radius: 20px;
            padding: 40px;
            max-width: 450px;
            width: 90%;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.4);
            text-align: center;
            position: relative;
            animation: modalSlideIn 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
            overflow: hidden;
        }
        
        @keyframes modalSlideIn {
            from {
                opacity: 0;
                transform: scale(0.7) translateY(-50px);
            }
            to {
                opacity: 1;
                transform: scale(1) translateY(0);
            }
        }
        
        .lock-modal::before {
            content: '';
            position: absolute;
            top: -50%;
            left: -50%;
            width: 200%;
            height: 200%;
            background: linear-gradient(45deg, transparent, rgba(255, 255, 255, 0.1), transparent);
            animation: shimmer 3s infinite;
        }
        
        @keyframes shimmer {
            0% { transform: translateX(-100%) translateY(-100%) rotate(45deg); }
            100% { transform: translateX(100%) translateY(100%) rotate(45deg); }
        }
        
        .lock-modal-content {
            position: relative;
            z-index: 1;
        }
        
        .lock-icon-wrapper {
            width: 100px;
            height: 100px;
            margin: 0 auto 25px;
            background: rgba(255, 255, 255, 0.2);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            animation: lockBounce 2s infinite;
        }
        
        @keyframes lockBounce {
            0%, 100% { transform: translateY(0); }
            50% { transform: translateY(-10px); }
        }
        
        .lock-icon-wrapper i {
            font-size: 50px;
            color: #fff;
        }
        
        .lock-modal h2 {
            color: #fff;
            font-family: 'Poppins', sans-serif;
            font-weight: 700;
            font-size: 28px;
            margin-bottom: 15px;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
        }
        
        .lock-modal p {
            color: rgba(255, 255, 255, 0.95);
            font-size: 16px;
            line-height: 1.6;
            margin-bottom: 25px;
        }
        
        .lock-modal-button {
            background: #fff;
            color: #667eea;
            border: none;
            padding: 15px 40px;
            border-radius: 50px;
            font-weight: 600;
            font-size: 16px;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
            font-family: 'Poppins', sans-serif;
        }
        
        .lock-modal-button:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
            background: #f0f0f0;
        }
        
        .countdown {
            display: inline-block;
            font-weight: 700;
            color: #ffd700;
            font-size: 18px;
            margin-top: 10px;
        }
        
        .progress-bar-container {
            width: 100%;
            height: 4px;
            background: rgba(255, 255, 255, 0.3);
            border-radius: 2px;
            margin-top: 20px;
            overflow: hidden;
        }
        
        .progress-bar {
            height: 100%;
            background: #ffd700;
            width: 100%;
            animation: progressShrink 3s linear;
        }
        
        @keyframes progressShrink {
            from { width: 100%; }
            to { width: 0%; }
        }