/* Styles for the chapter index table */
        .chapter-table {
            width: 100%;
            border-collapse: separate;
            border-spacing: 0 10px; /* Space between rows */
        }

        .chapter-table tr {
            background-color: #fff;
            border-radius: 8px;
            box-shadow: 0 2px 8px rgba(0,0,0,0.05);
            transition: all 0.2s ease-in-out;
        }

        .chapter-table tr:hover {
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
            transform: translateY(-2px);
        }

        .chapter-table td {
            padding: 15px 20px;
            vertical-align: top;
        }

        .chapter-table td:first-child {
            border-top-left-radius: 8px;
            border-bottom-left-radius: 8px;
        }

        .chapter-table td:last-child {
            border-top-right-radius: 8px;
            border-bottom-right-radius: 8px;
        }

        .chapter-name-title {
            font-weight: bold;
            color: #1e5799;
            font-size: 1.1em;
            margin-bottom: 5px;
        }

        .author-name {
            font-size: 0.9em;
            color: #6c757d;
        }

        .video-list-item {
            list-style: none;
            padding: 0;
            margin-top: 10px;
        }

        .video-list-item li {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 8px 0;
            border-top: 1px dashed #e9ecef;
        }

        .video-list-item li:first-child {
            border-top: none;
        }

        .video-title {
            color: #495057;
            font-size: 0.95em;
        }

        .btn-watch-video {
            background: linear-gradient(45deg, #28a745, #218838);
            color: white;
            border: none;
            border-radius: 20px;
            padding: 8px 15px;
            font-size: 0.85em;
            transition: all 0.3s ease;
            text-decoration: none; /* Ensure no underline */
        }

        .btn-watch-video:hover {
            transform: translateY(-2px);
            box-shadow: 0 4px 8px rgba(40, 167, 69, 0.3);
            color: white; /* Keep text white on hover */
        }

        .chapter-header {
            background-color: #f0f8ff; /* Light blue background for header */
            padding: 15px 20px;
            border-radius: 8px;
            margin-bottom: 20px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.05);
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .chapter-header h4 {
            margin: 0;
            color: #1e5799;
            font-weight: 600;
        }

        .chapter-header .badge {
            font-size: 0.9em;
            padding: 8px 12px;
            border-radius: 15px;
        }


        .dot-loader {
            width: 30px;
            height: 30px;
            border: 4px solid rgba(0, 123, 255, 0.2); /* subtle outer ring */
            border-top: 4px solid #007bff; /* vibrant blue arc */
            border-radius: 50%;
            animation: spin 1s ease-in-out infinite;
            margin: 10px auto;
        }

          @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
          }

        @media (max-width: 992px) {
            .main-container {
                flex-direction: column;
                height: auto;
            }
            .left-panel, .center-panel, .right-panel {
                width: 100%;
                margin-right: 0;
            }
            .left-panel, .center-panel {
                margin-bottom: 15px;
            }
        }