/* RESET */
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', sans-serif;
        }

        /* BODY */
        body {
            background: #f4f6f9;
        }

        /* CONTAINER */
        .container {
            width: 100%;
            max-width: 400px;
            margin: 80px auto;
        }

        /* CARD */
        .card {
            background: #fff;
            padding: 25px;
            border-radius: 10px;
            box-shadow: 0 5px 20px rgba(0,0,0,0.1);
        }

        /* HEADING */
        .card h2 {
            text-align: center;
            margin-bottom: 20px;
        }

        /* INPUT */
        input {
            width: 100%;
            padding: 10px;
            margin-bottom: 12px;
            border: 1px solid #ddd;
            border-radius: 6px;
            outline: none;
        }

        input:focus {
            border-color: #007bff;
        }

        /* BUTTON */
        button {
            width: 100%;
            padding: 10px;
            border: none;
            background: #007bff;
            color: white;
            font-weight: bold;
            border-radius: 6px;
            cursor: pointer;
            transition: background 0.2s;
        }

        button:hover {
            background: #0056b3;
        }

        /* LINKS */
        a {
            text-decoration: none;
            color: #007bff;
        }

        /* ALERT */
        .alert {
            padding: 10px;
            margin-bottom: 10px;
            border-radius: 5px;
        }

        .success {
            background: #d4edda;
            color: #155724;
        }

        .error {
            background: #f8d7da;
            color: #721c24;
        }

        /* DASHBOARD */
        .dashboard {
            display: flex;
            min-height: 100vh;
        }

        /* SIDEBAR */
        .sidebar {
            width: 220px;
            height: 100vh;
            background: #111827;
            color: #fff;
            padding: 20px;
            position: sticky;
            top: 0;
            overflow-y: auto;
        }

        .sidebar h3 {
            margin-bottom: 20px;
            font-weight: 600;
            border-left: 3px solid #007bff;
            padding-left: 10px;
        }

        .sidebar a {
            display: block;
            color: #ccc;
            padding: 10px;
            border-radius: 6px;
            margin-bottom: 8px;
            transition: all 0.2s;
        }

        .sidebar a i {
            width: 24px;
            margin-right: 8px;
        }

        .sidebar a:hover {
            background: #1f2937;
            color: #fff;
        }

        /* CONTENT */
        .content {
            flex: 1;
            padding: 20px;
            background: #f4f6f9;
        }

        /* TABLE */
        table {
            width: 100%;
            border-collapse: collapse;
            background: white;
            border-radius: 12px;
            overflow: hidden;
            box-shadow: 0 1px 3px rgba(0,0,0,0.05);
        }

        table th, table td {
            padding: 12px 10px;
            border-bottom: 1px solid #eee;
            text-align: left;
        }

        table th {
            background: #007bff;
            color: white;
            font-weight: 600;
        }

        table tr:hover {
            background: #f9fafb;
        }

        /* BUTTON SMALL */
        .btn-small {
            padding: 6px 12px;
            background: #dc3545;
            color: white;
            border-radius: 20px;
            border: none;
            font-size: 0.75rem;
            cursor: pointer;
            transition: 0.2s;
            font-weight: bold;
        }

        .btn-small:hover {
            background: #bb2d3b;
        }

        .whatsapp-btn {
            background: #25D366;
            color: white;
            padding: 10px 18px;
            border-radius: 40px;
            display: inline-flex;
            align-items: center;
            gap: 8px;
            font-weight: bold;
            transition: 0.2s;
            border: none;
            font-size: 0.9rem;
        }

        .whatsapp-btn:hover {
            background: #1ebe5d;
            transform: scale(1.02);
        }

        /* ADDITIONAL UI */
        .header-actions {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 24px;
            flex-wrap: wrap;
            gap: 12px;
        }

        .logout-btn {
            background: #6c757d;
            width: auto;
            padding: 8px 18px;
            border-radius: 30px;
        }

        .logout-btn:hover {
            background: #5a6268;
        }

        .add-contact-btn {
            background: #28a745;
            width: auto;
            padding: 8px 20px;
            border-radius: 30px;
        }

        .add-contact-btn:hover {
            background: #218838;
        }

        .empty-row td {
            text-align: center;
            padding: 30px;
            color: #6c757d;
        }

        /* modal (light) */
        .modal-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0,0,0,0.5);
            display: flex;
            align-items: center;
            justify-content: center;
            z-index: 1000;
        }
        .modal-card {
            max-width: 400px;
            width: 90%;
        }
        .flex-btns {
            display: flex;
            gap: 12px;
            margin-top: 10px;
        }
        .flex-btns button {
            width: auto;
            flex: 1;
        }
        .cancel-modal {
            background: #6c757d;
        }
        .cancel-modal:hover {
            background: #5a6268;
        }

        /* responsiveness */
        @media (max-width: 680px) {
            .dashboard {
                flex-direction: column;
            }
            .sidebar {
                width: 100%;
                height: auto;
                position: relative;
                padding: 15px;
            }
            .sidebar a {
                display: inline-block;
                margin-right: 8px;
            }
            table th, table td {
                padding: 8px 6px;
                font-size: 0.85rem;
            }
            .whatsapp-btn {
                padding: 6px 12px;
                font-size: 0.75rem;
            }
        }