.transition-colors {
            transition: background-color 0.3s ease, color 0.3s ease;
        }
        
        .lecture-btn {
            transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            position: relative;
            overflow: hidden;
        }
        
        .lecture-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 7px 14px rgba(0, 0, 0, 0.2);
        }
        
        .lecture-btn:active {
            transform: translateY(-1px);
        }
        
        .lecture-btn::after {
            content: '';
            position: absolute;
            top: 50%;
            left: 50%;
            width: 5px;
            height: 5px;
            background: rgba(255, 255, 255, 0.5);
            opacity: 0;
            border-radius: 100%;
            transform: scale(1, 1) translate(-50%, -50%);
            transform-origin: 50% 50%;
        }
        
        .lecture-btn:focus:not(:active)::after {
            animation: ripple 1s ease-out;
        }
        
        @keyframes ripple {
            0% {
                transform: scale(0, 0);
                opacity: 0.5;
            }
            100% {
                transform: scale(20, 20);
                opacity: 0;
            }
        }
        
        .lecture-content {
            display: none;
        }
        
        .lecture-content.active {
            display: block;
        }
        
        /* Enhanced animations for search and modal */
        @keyframes searchPulse {
            0% { transform: scale(1); }
            50% { transform: scale(1.05); }
            100% { transform: scale(1); }
        }

        #search-input {
            animation: fadeIn 0.3s ease-out;
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
        }

        #search-input:focus {
            transform: translateY(-1px);
            box-shadow: 0 4px 12px rgba(59, 130, 246, 0.25);
        }

        #search-button:hover svg {
            animation: searchPulse 1s infinite;
        }

        .video-modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background-color: rgba(0, 0, 0, 0.9);
            z-index: 1000;
            justify-content: center;
            align-items: center;
            padding: 20px;
            opacity: 0;
            transition: all 0.4s cubic-bezier(0.19, 1, 0.22, 1);
            backdrop-filter: blur(5px);
        }
        
        .video-modal.active {
            display: flex;
            opacity: 1;
        }
        
        .video-container {
            position: relative;
            width: 85%;
            max-width: 1100px;
            background-color: #000;
            border-radius: 16px;
            overflow: hidden;
            box-shadow: 0 15px 40px rgba(0, 0, 0, 0.8);
            transform: scale(0.95);
            transition: transform 0.5s cubic-bezier(0.19, 1, 0.22, 1);
        }
        
        .video-modal.active .video-container {
            transform: scale(1);
        }
        
        .video-container iframe {
            width: 100%;
            height: 100%;
            border: none;
            aspect-ratio: 16/9;
        }
        
        /* Video controls and UI enhancements */
        .video-progress-container {
            position: relative;
            width: 100%;
            height: 6px;
            background-color: rgba(255, 255, 255, 0.2);
            cursor: pointer;
            transition: height 0.2s ease;
        }
        
        .video-progress-container:hover {
            height: 8px;
        }
        
        .video-progress-bar {
            height: 100%;
            background: linear-gradient(90deg, #3b82f6, #8b5cf6);
            width: 0%;
            border-radius: 0 3px 3px 0;
            transition: width 0.3s ease;
        }
        
        .video-info {
            position: absolute;
            top: 15px;
            left: 15px;
            background-color: rgba(0, 0, 0, 0.7);
            color: white;
            padding: 8px 12px;
            border-radius: 8px;
            font-size: 14px;
            font-weight: 500;
            z-index: 10;
            opacity: 1;
            transition: opacity 0.3s ease;
        }
        
        .video-container:hover .video-info {
            opacity: 0.3;
        }
        
        .video-container:hover .video-info:hover {
            opacity: 1;
        }
        
        /* Mini player styles */
        .mini-player {
            position: fixed;
            bottom: 20px;
            right: 20px;
            width: 300px;
            height: 169px;
            background: #000;
            border-radius: 8px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.5);
            z-index: 900;
            overflow: hidden;
            transform: translateY(200%);
            transition: transform 0.3s ease;
        }
        
        .mini-player.active {
            transform: translateY(0);
        }
        
        .mini-player-close {
            position: absolute;
            top: 5px;
            right: 5px;
            background: rgba(0, 0, 0, 0.7);
            color: white;
            border: none;
            border-radius: 50%;
            width: 24px;
            height: 24px;
            font-size: 14px;
            display: flex;
            align-items: center;
            justify-content: center;
            cursor: pointer;
            z-index: 10;
        }
        
        #video-player {
            width: 100%;
            height: 100%;
            min-height: 360px;
            background-color: #000;
        }
        
        .close-btn {
            position: absolute;
            top: 15px;
            right: 15px;
            background-color: rgba(255, 255, 255, 0.2);
            color: white;
            border: none;
            border-radius: 50%;
            width: 40px;
            height: 40px;
            font-size: 22px;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            z-index: 1001;
            transition: all 0.2s ease;
            backdrop-filter: blur(5px);
        }
        
        .close-btn:hover {
            background-color: rgba(255, 255, 255, 0.3);
            transform: scale(1.1);
        }
        
        .video-progress-container {
            position: absolute;
            bottom: 0;
            left: 0;
            right: 0;
            height: 5px;
            background-color: rgba(255, 255, 255, 0.2);
            z-index: 1002;
        }
        
        .video-progress-bar {
            height: 100%;
            background: linear-gradient(to right, #3b82f6, #8b5cf6);
            width: 0%;
            transition: width 0.3s ease;
        }
        
        .video-info {
            position: absolute;
            top: 15px;
            left: 15px;
            background-color: rgba(0, 0, 0, 0.6);
            color: white;
            padding: 8px 12px;
            border-radius: 6px;
            font-size: 14px;
            backdrop-filter: blur(5px);
            z-index: 1001;
        }

        /* Custom checkbox styling */
        input[type="checkbox"] {
            appearance: none; /* Remove default checkbox styling */
            width: 24px;
            height: 24px;
            border: 2px solid #ccc;
            border-radius: 50%; /* Make it circular */
            outline: none;
            cursor: pointer;
            transition: all 0.3s ease;
            background-color: transparent; /* Default transparent background */
            position: relative;
        }

        input[type="checkbox"]::before {
            content: '';
            position: absolute;
            top: 50%;
            left: 50%;
            width: 12px;
            height: 12px;
            background-color: transparent;
            border-radius: 50%;
            transform: translate(-50%, -50%) scale(0);
            transition: all 0.3s ease;
        }

        input[type="checkbox"]:hover {
            border-color: #4CAF50; /* Green border on hover */
            box-shadow: 0 0 8px rgba(76, 175, 80, 0.5); /* Green glow effect */
        }

        input[type="checkbox"]:checked {
            background-color: #4CAF50; /* Green background when checked */
            border-color: #4CAF50;
        }

        input[type="checkbox"]:checked::before {
            background-color: white; /* White inner circle when checked */
            transform: translate(-50%, -50%) scale(1); /* Scale up the inner circle */
        }

        /* Custom checkbox styling */
        .lecture-checkbox {
            appearance: none; /* Remove default checkbox styling */
            width: 24px;
            height: 24px;
            border: 2px solid #ccc;
            border-radius: 50%; /* Make it circular */
            outline: none;
            cursor: pointer;
            transition: all 0.3s ease;
            background-color: transparent; /* Default transparent background */
            position: relative;
        }

        .lecture-checkbox::before {
            content: '';
            position: absolute;
            top: 50%;
            left: 50%;
            width: 12px;
            height: 12px;
            background-color: transparent;
            border-radius: 50%;
            transform: translate(-50%, -50%) scale(0);
            transition: all 0.3s ease;
        }

        .lecture-checkbox:hover {
            border-color: #4CAF50; /* Green border on hover */
            box-shadow: 0 0 8px rgba(76, 175, 80, 0.5); /* Green glow effect */
        }

        .lecture-checkbox:checked {
            background-color: #4CAF50; /* Green background when checked */
            border-color: #4CAF50;
        }

        .lecture-checkbox:checked::before {
            background-color: white; /* White inner circle when checked */
            transform: translate(-50%, -50%) scale(1); /* Scale up the inner circle */
        }

        /* Style for the active lecture button */
        .lecture-btn.bg-green-500 {
            background-color: #fc201c !important; /* Red background for active lecture */
            color: white !important;
        }
        
        /* Watch button styling */
        .watch-button {
            background: linear-gradient(to right, #3b82f6, #8b5cf6);
            color: white;
            font-weight: bold;
            padding: 10px 16px;
            border-radius: 10px;
            border: none;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            justify-content: center;
            margin-bottom: 10px;
            position: relative;
            overflow: hidden;
            box-shadow: 0 4px 10px rgba(59, 130, 246, 0.3);
        }
        
        .watch-button::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
            transition: 0.5s;
        }
        
        .watch-button:hover {
            transform: translateY(-3px);
            box-shadow: 0 6px 15px rgba(59, 130, 246, 0.4);
        }
        
        .watch-button:hover::before {
            left: 100%;
        }
        
        .watch-button:active {
            transform: translateY(-1px);
        }

        .hidden {
            display: none;
        }

        /* Style for lecture cards */
        @keyframes cardEnter {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .lecture-card {
            background: linear-gradient(135deg, #1e293b, #0f172a);
            border: 1px solid rgba(75, 85, 99, 0.3);
            border-radius: 16px;
            padding: 20px;
            box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
            transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            display: flex;
            flex-direction: column;
            justify-content: space-between;
            color: white;
            position: relative;
            overflow: hidden;
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            line-height: 1.6;
            letter-spacing: 0.01em;
            animation: cardEnter 0.6s ease-out;
        }

        .lecture-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 4px;
            background: linear-gradient(to right, #3b82f6, #8b5cf6, #ec4899);
            opacity: 0.7;
            transition: height 0.3s ease;
        }

        .lecture-card:hover {
            transform: translateY(-8px) scale(1.02); /* Enhanced lift effect */
            box-shadow: 0 12px 28px rgba(0, 0, 0, 0.25); /* Stronger shadow on hover */
        }
        
        .lecture-card:hover::before {
            height: 6px;
        }

        .lecture-card h3 {
            font-size: 1.25rem;
            font-weight: 700;
            margin-bottom: 12px;
            line-height: 1.3;
            letter-spacing: -0.01em;
            text-shadow: 0 1px 2px rgba(0, 0, 0, 0.2);
        }

        .lecture-card p {
            font-size: 0.9375rem;
            color: rgba(203, 213, 225, 0.9); /* Lighter text with transparency */
            margin-bottom: 16px;
            line-height: 1.7;
            letter-spacing: 0.01em;
        }

        .lecture-card .watch-button {
            background-color: #ef4444; /* Red button */
            color: white;
            font-weight: bold;
            padding: 8px 12px;
            border-radius: 8px;
            text-align: center;
            transition: background-color 0.3s ease;
        }

        .lecture-card .watch-button:hover {
            background-color: #dc2626; /* Darker red on hover */
        }

        /* Progress Bar Styling */
        #progress-bar {
            transition: width 0.3s ease-in-out; /* Smooth transition for width changes */
        }

        .bg-gray-700 {
            background-color: #374151; /* Dark gray background for the progress bar container */
        }

        .bg-green-500 {
            background-color: #22c55e; /* Green color for the progress bar */
        }

        .shadow-inner {
            box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2); /* Inner shadow for depth */
        }

        .bg-white {
            aspect-ratio: 1 / 1; /* Ensure square shape */
            object-fit: cover; /* Ensure the image covers the area */
        }

        .bg-white img {
            width: 100%;
            height: 100%;
            object-fit: contain; /* Ensures the entire image is visible without cropping */
            aspect-ratio: 1 / 1; /* Maintains a square aspect ratio */
            border-radius: 8px; /* Optional: Keeps the rounded corners */
        }