* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        :root {
            /* Light mode colors */
            --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            --container-bg: white;
            --header-gradient: linear-gradient(135deg, #2563eb, #3b82f6);
            --text-primary: #333;
            --text-secondary: #6b7280;
            --text-tertiary: #1f2937;
            --card-bg: white;
            --card-shadow: rgba(0,0,0,0.1);
            --border-color: #e5e7eb;
            --input-border: #e5e7eb;
            --filter-btn-bg: #f3f4f6;
            --filter-btn-hover: #e5e7eb;
            --modal-bg: rgba(0,0,0,0.5);
            --install-prompt-bg: #1f2937;
        }

        [data-theme="dark"] {
            /* Dark mode colors */
            --bg-gradient: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
            --container-bg: #0f172a;
            --header-gradient: linear-gradient(135deg, #1e293b, #334155);
            --text-primary: #e2e8f0;
            --text-secondary: #94a3b8;
            --text-tertiary: #f1f5f9;
            --card-bg: #1e293b;
            --card-shadow: rgba(0,0,0,0.3);
            --border-color: #334155;
            --input-border: #475569;
            --filter-btn-bg: #334155;
            --filter-btn-hover: #475569;
            --modal-bg: rgba(0,0,0,0.7);
            --install-prompt-bg: #374151;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: var(--bg-gradient);
            min-height: 100vh;
            color: var(--text-primary);
            transition: all 0.3s ease;
        }

        .container {
            max-width: 428px;
            margin: 0 auto;
            background: var(--container-bg);
            min-height: 100vh;
            box-shadow: 0 0 20px var(--card-shadow);
            position: relative;
            overflow-x: hidden;
            transition: all 0.3s ease;
        }

        /* Navigation overlay */
        .nav-overlay {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(0, 0, 0, 0.5);
            opacity: 0;
            visibility: hidden;
            transition: opacity 0.3s ease, visibility 0.3s ease;
            z-index: 998;
        }

        .nav-overlay.active {
            opacity: 1;
            visibility: visible;
        }

        /* Side Navigation */
        .side-nav {
            position: fixed;
            top: 0;
            left: -320px;
            width: 320px;
            height: 100%;
            background: var(--card-bg);
            box-shadow: 2px 0 10px var(--card-shadow);
            transition: left 0.3s ease;
            z-index: 999;
            padding: 2rem 1.5rem;
        }

        .side-nav.active {
            left: 0;
        }

        .nav-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 2rem;
            padding-bottom: 1rem;
            border-bottom: 1px solid var(--border-color);
        }

        .nav-title {
            font-size: 1.25rem;
            font-weight: 600;
            color: #2563eb;
        }

        .close-nav {
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            padding: 0.25rem;
            color: var(--text-secondary);
            transition: color 0.3s ease;
        }

        .close-nav:hover {
            color: var(--text-primary);
        }

        .nav-item {
            display: flex;
            align-items: center;
            padding: 0.75rem 0;
            cursor: pointer;
            border-radius: 0.375rem;
            transition: background-color 0.2s ease;
            margin-bottom: 0.5rem;
        }

        .nav-item:hover {
            background-color: var(--filter-btn-bg);
        }

        .nav-item-icon {
            margin-right: 0.75rem;
            font-size: 1.125rem;
        }

        .nav-item-text {
            font-weight: 500;
        }

        /* Dark mode toggle in nav */
        .dark-mode-section {
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0.75rem 0;
        }

        .toggle-switch {
            position: relative;
            width: 56px;
            height: 28px;
            background-color: #cbd5e1;
            border-radius: 14px;
            cursor: pointer;
            transition: background-color 0.3s ease;
        }

        .toggle-dot {
            position: absolute;
            top: 4px;
            left: 4px;
            width: 20px;
            height: 20px;
            background-color: white;
            border-radius: 50%;
            transition: transform 0.3s ease;
            box-shadow: 0 2px 4px rgba(0,0,0,0.2);
        }

        #darkModeToggle:checked + .toggle-switch {
            background-color: #3b82f6;
        }

        #darkModeToggle:checked + .toggle-switch .toggle-dot {
            transform: translateX(28px);
        }

        .sr-only {
            position: absolute;
            width: 1px;
            height: 1px;
            padding: 0;
            margin: -1px;
            overflow: hidden;
            clip: rect(0, 0, 0, 0);
            white-space: nowrap;
            border: 0;
        }

        /* Header with hamburger */
        .app-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 1rem 20px;
            background: var(--header-gradient);
            color: white;
        }

        .hamburger {
            display: flex;
            flex-direction: column;
            cursor: pointer;
            padding: 0.5rem;
            border: none;
            background: none;
            transition: transform 0.3s ease;
        }

        .hamburger:hover {
            transform: scale(1.1);
        }

        .hamburger span {
            width: 25px;
            height: 3px;
            background-color: white;
            margin: 3px 0;
            transition: 0.3s;
            border-radius: 2px;
        }

        .hamburger.active span:nth-child(1) {
            transform: rotate(-45deg) translate(-5px, 6px);
        }

        .hamburger.active span:nth-child(2) {
            opacity: 0;
        }

        .hamburger.active span:nth-child(3) {
            transform: rotate(45deg) translate(-5px, -6px);
        }

        .header {
            background: var(--header-gradient);
            color: white;
            padding: 20px;
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .header::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><circle cx="20" cy="20" r="2" fill="white" opacity="0.1"/><circle cx="80" cy="30" r="1" fill="white" opacity="0.2"/><circle cx="40" cy="70" r="1.5" fill="white" opacity="0.15"/></svg>');
            animation: float 20s infinite linear;
        }

        @keyframes float {
            0% { transform: translateX(0) translateY(0); }
            100% { transform: translateX(-100px) translateY(-100px); }
        }

        .header h1 {
            font-size: 1.8rem;
            font-weight: 700;
            margin-bottom: 5px;
            position: relative;
            z-index: 1;
        }

        .balance-card {
            background: rgba(255,255,255,0.15);
            backdrop-filter: blur(10px);
            border-radius: 15px;
            padding: 20px;
            margin-top: 15px;
            position: relative;
            z-index: 1;
        }

        .balance-amount {
            font-size: 2.2rem;
            font-weight: 800;
            margin-bottom: 8px;
        }

        .balance-label {
            opacity: 0.9;
            font-size: 0.9rem;
        }

        .stats-grid {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 15px;
            padding: 20px;
            margin-top: -10px;
        }

        .stat-card {
            background: var(--card-bg);
            border-radius: 12px;
            padding: 15px;
            box-shadow: 0 2px 10px var(--card-shadow);
            text-align: center;
            transition: transform 0.2s, box-shadow 0.2s;
        }

        .stat-card:hover {
            transform: translateY(-2px);
            box-shadow: 0 4px 20px var(--card-shadow);
        }

        .stat-amount {
            font-size: 1.4rem;
            font-weight: 700;
            margin-bottom: 5px;
        }

        .income { color: #10b981; }
        .expense { color: #ef4444; }

        .stat-label {
            color: var(--text-secondary);
            font-size: 0.85rem;
        }

        .quick-actions {
            padding: 0 20px 20px;
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 12px;
        }

        .action-btn {
            background: linear-gradient(135deg, #10b981, #059669);
            color: white;
            border: none;
            padding: 15px;
            border-radius: 10px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.2s;
            position: relative;
            overflow: hidden;
        }

        .action-btn.expense-btn {
            background: linear-gradient(135deg, #ef4444, #dc2626);
        }

        .action-btn:active {
            transform: scale(0.98);
        }

        .action-btn::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: left 0.5s;
        }

        .action-btn:hover::before {
            left: 100%;
        }

        .transactions-section {
            padding: 0 20px 80px;
        }

        .section-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 15px;
        }

        .section-title {
            font-size: 1.2rem;
            font-weight: 700;
            color: var(--text-tertiary);
        }

        .filter-btn {
            background: var(--filter-btn-bg);
            color: var(--text-primary);
            border: none;
            padding: 8px 12px;
            border-radius: 6px;
            font-size: 0.8rem;
            cursor: pointer;
            transition: all 0.2s;
        }

        .filter-btn:hover {
            background: var(--filter-btn-hover);
        }

        .transaction-list {
            space-y: 10px;
        }

        .transaction-item {
            background: var(--card-bg);
            border-radius: 12px;
            padding: 15px;
            box-shadow: 0 1px 3px var(--card-shadow);
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 10px;
            transition: transform 0.2s;
            position: relative;
        }

        .transaction-item:hover {
            transform: translateX(5px);
        }

        .transaction-info h4 {
            font-weight: 600;
            margin-bottom: 4px;
            color: var(--text-primary);
        }

        .transaction-date {
            color: var(--text-secondary);
            font-size: 0.8rem;
        }

        .transaction-amount {
            font-weight: 700;
            font-size: 1.1rem;
        }

        .modal-overlay {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: var(--modal-bg);
            display: none;
            justify-content: center;
            align-items: center;
            z-index: 1000;
            backdrop-filter: blur(5px);
        }

        .modal {
            background: var(--card-bg);
            border-radius: 20px;
            padding: 30px;
            width: 90%;
            max-width: 400px;
            animation: slideUp 0.3s ease;
        }

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

        .modal h2 {
            margin-bottom: 20px;
            color: var(--text-tertiary);
        }

        .form-group {
            margin-bottom: 15px;
        }

        .form-group label {
            display: block;
            margin-bottom: 5px;
            font-weight: 600;
            color: var(--text-primary);
        }

        .form-group input, .form-group select {
            width: 100%;
            padding: 12px;
            border: 2px solid var(--input-border);
            border-radius: 8px;
            font-size: 1rem;
            transition: border-color 0.2s;
            background: var(--card-bg);
            color: var(--text-primary);
        }

        .form-group input:focus, .form-group select:focus {
            outline: none;
            border-color: #3b82f6;
        }

        .modal-actions {
            display: flex;
            gap: 10px;
            margin-top: 20px;
        }

        .btn-cancel {
            flex: 1;
            padding: 12px;
            background: var(--filter-btn-bg);
            color: var(--text-primary);
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
            transition: background 0.2s;
        }

        .btn-cancel:hover {
            background: var(--filter-btn-hover);
        }

        .btn-save {
            flex: 1;
            padding: 12px;
            background: #3b82f6;
            color: white;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            font-weight: 600;
        }

        .empty-state {
            text-align: center;
            padding: 40px 20px;
            color: var(--text-secondary);
        }

        .empty-state h3 {
            color: var(--text-primary);
            margin-bottom: 8px;
        }

        .empty-state-icon {
            font-size: 3rem;
            margin-bottom: 15px;
            opacity: 0.5;
        }

        .install-prompt {
            position: fixed;
            bottom: 20px;
            left: 20px;
            right: 20px;
            background: var(--install-prompt-bg);
            color: white;
            padding: 15px;
            border-radius: 10px;
            display: none;
            align-items: center;
            justify-content: space-between;
            z-index: 1000;
        }

        .install-btn {
            background: #3b82f6;
            color: white;
            border: none;
            padding: 8px 16px;
            border-radius: 6px;
            cursor: pointer;
            font-weight: 600;
        }

        /* Dark mode specific navigation styles */
        [data-theme="dark"] .side-nav {
            background: var(--card-bg);
            box-shadow: 2px 0 10px rgba(0,0,0,0.5);
        }

        [data-theme="dark"] .nav-header {
            border-bottom-color: var(--border-color);
        }

        [data-theme="dark"] .nav-item:hover {
            background-color: var(--filter-btn-hover);
        }

        [data-theme="dark"] .close-nav {
            color: var(--text-secondary);
        }

        [data-theme="dark"] .close-nav:hover {
            color: var(--text-primary);
        }

        @keyframes slideIn {
            from { transform: translateX(100%); }
            to { transform: translateX(0); }
        }

        @media (max-width: 480px) {
            .stats-grid {
                padding: 15px;
            }
            
            .quick-actions {
                padding: 0 15px 15px;
            }
            
            .transactions-section {
                padding: 0 15px 80px;
            }

            .side-nav {
                width: 300px;
                left: -300px;
            }
        }