.App{font-family:Arial,sans-serif;max-width:1200px;margin:0 auto;padding:20px}.loading-screen{text-align:center;margin-top:50px}.spinner{border:5px solid #f3f3f3;border-top:5px solid #3498db;border-radius:50%;width:50px;height:50px;animation:spin 1s linear infinite;margin:20px auto}@keyframes spin{0%{transform:rotate(0)}to{transform:rotate(360deg)}}.App-header{text-align:center;margin-bottom:30px}.tabs{display:flex;margin-bottom:20px;border-bottom:1px solid #ddd}.tabs button{padding:10px 20px;background:none;border:none;cursor:pointer;font-size:16px;margin-right:5px}.tabs button.active{border-bottom:2px solid #3498db;font-weight:700}.network-status{margin-bottom:15px;font-size:14px}.message{padding:10px;margin-bottom:20px;background:#f8f8f8;border-left:4px solid #3498db}.batches-list ul{list-style:none;padding:0}.batch-button{padding:10px 15px;background:#3498db;color:#fff;border:none;border-radius:4px;cursor:pointer;margin:5px 0;width:200px;text-align:left}.back-button{background:#f0f0f0;border:1px solid #ddd;padding:5px 10px;margin-bottom:15px;cursor:pointer}.attendance-list table,.student-list table,.marks-table table{width:100%;border-collapse:collapse;margin-bottom:20px}.attendance-list th,.student-list th,.marks-table th{background:#f5f5f5;padding:10px;text-align:left}.attendance-list td,.student-list td,.marks-table td{padding:10px;border-bottom:1px solid #ddd}.mark-present{background:#2ecc71;color:#fff;border:none;padding:5px 10px;border-radius:3px;cursor:pointer}.mark-absent{background:#e74c3c;color:#fff;border:none;padding:5px 10px;border-radius:3px;cursor:pointer}.send-button{background:#3498db;color:#fff;border:none;padding:10px 15px;border-radius:4px;cursor:pointer;margin-top:10px}.send-button:disabled{background:#95a5a6;cursor:not-allowed}.delete-button{background:#e74c3c;color:#fff;border:none;padding:5px 10px;border-radius:3px;cursor:pointer}.view-button{background:#3498db;color:#fff;border:none;padding:5px 10px;border-radius:3px;cursor:pointer}.add-batch,.add-student,.test-info{margin-bottom:20px;padding:15px;background:#f9f9f9;border-radius:4px}.add-batch input,.add-student input,.test-info input{padding:8px;margin-right:10px;border:1px solid #ddd;border-radius:4px}.add-batch button,.add-student button{padding:8px 15px;background:#2ecc71;color:#fff;border:none;border-radius:4px;cursor:pointer}.absent{color:#e74c3c;font-weight:700}.app-footer{text-align:center;margin-top:30px;padding-top:20px;border-top:1px solid #ddd;color:#7f8c8d}