:root {
            --primary: #6c5ce7;
            --primary-light: #a29bfe;
            --secondary: #00cec9;
            --accent: #fd79a8;
            --success: #00b894;
            --danger: #d63031;
            --warning: #fdcb6e;
            --dark: #2d3436;
            --darker: #1e2224;
            --light: #dfe6e9;
            --card-bg: #2d3436;
            --text: #f5f6fa;
            --shadow: rgba(0, 0, 0, 0.3);
            --gradient: linear-gradient(135deg, #6c5ce7, #00cec9);
        }

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

        body {
            background: linear-gradient(135deg, #1e2224, #2d3436);
            color: var(--text);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            overflow-x: hidden;
        }

        .container {
            width: 100%;
            max-width: 1400px;
            margin: 0 auto;
            padding: 20px;
        }

        /* Login Page Styles */
        .login-container {
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            background: linear-gradient(135deg, #1e2224, #2d3436);
            position: relative;
            overflow: hidden;
        }

        .login-container::before {
            content: '';
            position: absolute;
            width: 200%;
            height: 200%;
            background: radial-gradient(circle, var(--primary) 0%, transparent 70%);
            opacity: 0.1;
            animation: pulse 15s infinite linear;
        }

        .login-form {
            background-color: rgba(45, 52, 54, 0.9);
            padding: 50px 40px;
            border-radius: 20px;
            box-shadow: 0 15px 35px var(--shadow);
            width: 100%;
            max-width: 450px;
            z-index: 10;
            position: relative;
            backdrop-filter: blur(10px);
            border: 1px solid rgba(255, 255, 255, 0.1);
            animation: slideUp 0.8s ease;
        }

        .login-form h2 {
            text-align: center;
            margin-bottom: 30px;
            color: var(--text);
            font-size: 32px;
            font-weight: 700;
            background: var(--gradient);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        .form-group {
            margin-bottom: 25px;
            position: relative;
        }

        .form-group label {
            display: block;
            margin-bottom: 10px;
            font-weight: 600;
            color: var(--light);
        }

        .form-group input {
            width: 100%;
            padding: 15px 20px;
            background: rgba(255, 255, 255, 0.1);
            border: 2px solid rgba(255, 255, 255, 0.1);
            border-radius: 12px;
            font-size: 16px;
            transition: all 0.3s;
            color: var(--text);
        }

        .form-group input:focus {
            border-color: var(--primary);
            outline: none;
            box-shadow: 0 0 0 3px rgba(108, 92, 231, 0.3);
            background: rgba(255, 255, 255, 0.15);
        }

        .btn {
            display: inline-block;
            padding: 15px 25px;
            background: var(--gradient);
            color: white;
            border: none;
            border-radius: 12px;
            font-size: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            text-align: center;
            width: 100%;
            box-shadow: 0 5px 15px rgba(108, 92, 231, 0.4);
        }

        .btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 20px rgba(108, 92, 231, 0.6);
        }

        .error-message {
            color: var(--danger);
            text-align: center;
            margin-top: 15px;
            display: none;
            font-weight: 600;
        }

        /* Main App Styles */
        .app-container {
            display: none;
            flex-direction: column;
            min-height: 100vh;
        }

        header {
            background: rgba(45, 52, 54, 0.9);
            padding: 20px 0;
            box-shadow: 0 4px 20px var(--shadow);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            z-index: 100;
            position: relative;
        }

        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            font-size: 28px;
            font-weight: 700;
            display: flex;
            align-items: center;
        }

        .logo i {
            margin-right: 10px;
            font-size: 32px;
            background: var(--gradient);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        .user-info {
            display: flex;
            align-items: center;
        }

        .user-info span {
            margin-right: 15px;
        }

        .logout-btn {
            background: rgba(255, 255, 255, 0.1);
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.3s;
            display: flex;
            align-items: center;
        }

        .logout-btn:hover {
            background: rgba(255, 255, 255, 0.2);
        }

        .hamburger {
            display: none;
            background: none;
            border: none;
            color: white;
            font-size: 24px;
            cursor: pointer;
            z-index: 101;
        }

        nav {
            background-color: rgba(45, 52, 54, 0.9);
            padding: 15px 0;
            box-shadow: 0 4px 15px var(--shadow);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            z-index: 99;
            position: relative;
        }

        .nav-container {
            display: flex;
            justify-content: space-between;
            align-items: center;
            position: relative;
        }

        .nav-links {
            display: flex;
            list-style: none;
        }

        .nav-links li {
            margin-right: 15px;
        }

        .nav-links a {
            text-decoration: none;
            color: var(--text);
            font-weight: 600;
            padding: 10px 20px;
            border-radius: 10px;
            transition: all 0.3s;
            display: flex;
            align-items: center;
        }

        .nav-links a i {
            margin-right: 8px;
        }

        .nav-links a:hover, .nav-links a.active {
            background: var(--gradient);
            color: white;
            box-shadow: 0 5px 15px rgba(108, 92, 231, 0.4);
        }

        .search-container {
            display: flex;
            gap: 10px;
            align-items: center;
        }

        .search-container input {
            padding: 10px 15px;
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            color: var(--text);
        }

        .search-container button {
            background: var(--gradient);
            color: white;
            border: none;
            padding: 10px 20px;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.3s;
        }

        .search-container button:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(108, 92, 231, 0.4);
        }

        main {
            flex: 1;
            padding: 30px 0;
        }

        .page-title {
            margin-bottom: 30px;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .page-title h1 {
            font-size: 36px;
            background: var(--gradient);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            font-weight: 700;
        }

        .export-buttons {
            display: flex;
            gap: 10px;
        }

        .export-buttons button {
            padding: 10px 20px;
            background: var(--gradient);
            color: white;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.3s;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .export-buttons button:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(108, 92, 231, 0.4);
        }

        .cards-container {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
            gap: 25px;
            margin-bottom: 40px;
        }

        .card {
            background: var(--card-bg);
            border-radius: 20px;
            padding: 25px;
            box-shadow: 0 10px 25px var(--shadow);
            transition: all 0.3s;
            cursor: pointer;
            border: 1px solid rgba(255, 255, 255, 0.1);
            position: relative;
            overflow: hidden;
        }

        .card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 5px;
            background: var(--gradient);
        }

        .card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px var(--shadow);
        }

        .card i {
            font-size: 40px;
            margin-bottom: 15px;
            background: var(--gradient);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }

        .card h3 {
            font-size: 20px;
            margin-bottom: 10px;
            color: var(--light);
        }

        .card .amount {
            font-size: 32px;
            font-weight: 700;
            margin-bottom: 5px;
        }

        .card .last-update {
            font-size: 14px;
            color: var(--primary-light);
        }

        .table-container {
            background: var(--card-bg);
            border-radius: 20px;
            padding: 25px;
            box-shadow: 0 10px 25px var(--shadow);
            overflow-x: auto;
            border: 1px solid rgba(255, 255, 255, 0.1);
        }

        table {
            width: 100%;
            border-collapse: collapse;
        }

        table th, table td {
            padding: 15px;
            text-align: left;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        }

        table th {
            background-color: rgba(255, 255, 255, 0.05);
            font-weight: 600;
            color: var(--primary-light);
        }

        table tr:last-child td {
            border-bottom: none;
        }

        table tr:hover {
            background-color: rgba(255, 255, 255, 0.05);
        }

        .status-paid {
            color: var(--success);
            font-weight: 600;
        }

        .status-not-paid {
            color: var(--danger);
            font-weight: 600;
        }

        .total-row {
            background-color: rgba(255, 255, 255, 0.05);
            font-weight: 700;
        }

        .back-btn {
            display: inline-flex;
            align-items: center;
            gap: 8px;
            margin-bottom: 20px;
            padding: 10px 20px;
            background: var(--gradient);
            color: white;
            text-decoration: none;
            border-radius: 10px;
            transition: all 0.3s;
        }

        .back-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(108, 92, 231, 0.4);
        }

        footer {
            background-color: var(--darker);
            color: white;
            text-align: center;
            padding: 20px 0;
            margin-top: auto;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
        }

        /* Animations */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes slideUp {
            from { opacity: 0; transform: translateY(50px); }
            to { opacity: 1; transform: translateY(0); }
        }

        @keyframes pulse {
            0% { transform: translate(-50%, -50%) scale(1); }
            50% { transform: translate(-50%, -50%) scale(1.1); }
            100% { transform: translate(-50%, -50%) scale(1); }
        }

        .fade-in {
            animation: fadeIn 0.5s ease;
        }

        /* Loading Spinner */
        .spinner {
            border: 5px solid rgba(255, 255, 255, 0.3);
            border-radius: 50%;
            border-top: 5px solid var(--primary);
            width: 50px;
            height: 50px;
            animation: spin 1s linear infinite;
            margin: 20px auto;
        }

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

        /* Mobile Styles */
        @media (max-width: 992px) {
            .nav-links {
                display: none;
                position: absolute;
                top: 100%;
                left: 0;
                width: 100%;
                background: var(--darker);
                flex-direction: column;
                padding: 20px;
                box-shadow: 0 10px 20px var(--shadow);
                z-index: 100;
            }

            .nav-links.active {
                display: flex;
            }

            .nav-links li {
                margin: 10px 0;
            }

            .hamburger {
                display: block;
            }

            .search-container {
                flex-direction: column;
                width: 100%;
                margin-top: 15px;
            }

            .search-container input {
                width: 100%;
            }

            .cards-container {
                grid-template-columns: 1fr;
            }

            .header-content {
                flex-direction: column;
                align-items: flex-start;
            }

            .user-info {
                margin-top: 15px;
                width: 100%;
                justify-content: space-between;
            }

            .page-title {
                flex-direction: column;
                align-items: flex-start;
                gap: 15px;
            }

            .export-buttons {
                width: 100%;
                justify-content: space-between;
            }
        }

        @media (max-width: 576px) {
            .login-form {
                padding: 30px 20px;
            }

            .container {
                padding: 15px;
            }

            .card {
                padding: 20px;
            }

            .table-container {
                padding: 15px;
            }
        }