:root {
    /* Dark Theme Colors */
    --bg-primary: #0a0e1a;
    --bg-secondary: #131720;
    --bg-tertiary: #1a1f2e;
    --bg-card: #1e2433;
    --bg-elevated: #252b3d;
    
    /* Accent Colors */
    --accent-primary: #00d9ff;
    --accent-secondary: #7c3aed;
    --accent-success: #10b981;
    --accent-warning: #f59e0b;
    --accent-danger: #ef4444;
    
    /* Text Colors */
    --text-primary: #e2e8f0;
    --text-secondary: #94a3b8;
    --text-tertiary: #64748b;
    
    /* Borders */
    --border-color: #2d3548;
    --border-focus: var(--accent-primary);
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(0, 217, 255, 0.3);
    
    /* Fonts */
    --font-primary: 'Sora', sans-serif;
    --font-mono: 'JetBrains Mono', monospace;
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 400ms ease;
}

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

body {
    font-family: var(--font-primary);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Animated Background */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(ellipse at 20% 30%, rgba(124, 58, 237, 0.1) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 70%, rgba(0, 217, 255, 0.1) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

#app {
    position: relative;
    z-index: 1;
}

/* Screen Management */
.screen {
    display: none;
    opacity: 0;
    transition: opacity var(--transition-slow);
}

.screen.active {
    display: block;
    animation: fadeIn var(--transition-slow) forwards;
}

@keyframes fadeIn {
    to { opacity: 1; }
}

/* ==================== AUTH SCREEN ==================== */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
}

.auth-brand {
    text-align: center;
    margin-bottom: 3rem;
    animation: slideDown 0.6s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.brand-icon {
    width: 80px;
    height: 80px;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    border-radius: 20px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    font-weight: 700;
    margin: 0 auto 1.5rem;
    box-shadow: var(--shadow-glow);
    animation: pulse 3s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { transform: scale(1); }
    50% { transform: scale(1.05); }
}

.auth-brand h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.tagline {
    color: var(--text-secondary);
    font-size: 1rem;
}

.auth-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    max-width: 420px;
    width: 100%;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.6s ease 0.2s backwards;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.auth-tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    background: var(--bg-tertiary);
    border-radius: 12px;
    padding: 0.5rem;
}

.auth-tab {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-family: var(--font-primary);
    font-size: 0.95rem;
    font-weight: 600;
    padding: 0.75rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition-base);
}

.auth-tab.active {
    background: var(--accent-primary);
    color: var(--bg-primary);
    box-shadow: 0 2px 8px rgba(0, 217, 255, 0.3);
}

.auth-form {
    display: none;
}

.auth-form.active {
    display: block;
    animation: fadeIn 0.3s;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group input,
.form-group select {
    width: 100%;
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: 10px;
    padding: 0.875rem 1rem;
    color: var(--text-primary);
    font-family: var(--font-primary);
    font-size: 1rem;
    transition: all var(--transition-base);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 4px rgba(0, 217, 255, 0.1);
}

.btn-primary,
.btn-secondary,
.btn-icon,
.btn-add,
.btn-edit {
    font-family: var(--font-primary);
    font-weight: 600;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.btn-primary {
    width: 100%;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    color: white;
    padding: 1rem;
    font-size: 1rem;
    box-shadow: 0 4px 12px rgba(0, 217, 255, 0.3);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 217, 255, 0.4);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-secondary {
    width: 100%;
    background: var(--bg-tertiary);
    color: var(--text-primary);
    padding: 1rem;
    font-size: 1rem;
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-elevated);
    border-color: var(--accent-primary);
}

.demo-login {
    margin-top: 1.5rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
}

/* ==================== MAIN APP ==================== */
.app-header {
    background: var(--bg-card);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.brand-small {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-weight: 700;
    font-size: 1.25rem;
}

.brand-icon-small {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--accent-primary), var(--accent-secondary));
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.header-actions {
    display: flex;
    gap: 0.5rem;
}

.btn-icon {
    width: 40px;
    height: 40px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0;
}

.btn-icon:hover {
    background: var(--bg-elevated);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

/* ==================== DASHBOARD ==================== */
.dashboard {
    max-width: 1400px;
    margin: 0 auto;
    padding: 2rem;
}

.month-navigation {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.month-controls {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.btn-month {
    width: 40px;
    height: 40px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
}

.btn-month:hover {
    background: var(--bg-elevated);
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.month-input {
    background: var(--bg-tertiary);
    border: 2px solid var(--border-color);
    border-radius: 10px;
    padding: 0.75rem 1rem;
    color: var(--text-primary);
    font-family: var(--font-primary);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.month-input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 4px rgba(0, 217, 255, 0.1);
}

.month-input::-webkit-calendar-picker-indicator {
    cursor: pointer;
    filter: invert(1);
}

.btn-close-month {
    background: linear-gradient(135deg, var(--accent-success), #059669);
    color: white;
    border: none;
    border-radius: 10px;
    padding: 0.75rem 1.5rem;
    font-family: var(--font-primary);
    font-size: 0.875rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    box-shadow: 0 2px 8px rgba(16, 185, 129, 0.3);
}

.btn-close-month:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(16, 185, 129, 0.4);
}

.summary-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.summary-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
    position: relative;
    overflow: hidden;
    transition: all var(--transition-base);
}

.summary-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
}

.summary-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
    border-color: var(--accent-primary);
}

.card-label {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 0.5rem;
}

.card-value {
    font-size: 2rem;
    font-weight: 700;
    font-family: var(--font-mono);
    margin-bottom: 0.5rem;
}

.balance-card .card-value { color: var(--accent-primary); }
.final-card .card-value { color: var(--accent-secondary); }
.income-card .card-value { color: var(--accent-success); }
.expense-card .card-value { color: var(--accent-danger); }

.card-change {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.change-icon {
    font-size: 1.25rem;
}

.card-detail {
    color: var(--text-tertiary);
    font-size: 0.875rem;
}

.btn-edit {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
    border: 1px solid var(--border-color);
    margin-top: 0.75rem;
}

.btn-edit:hover {
    background: var(--bg-elevated);
    color: var(--accent-primary);
    border-color: var(--accent-primary);
}

/* ==================== CHART SECTION ==================== */
.chart-section {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 2rem;
    margin-bottom: 2rem;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.section-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
}

.chart-controls {
    display: flex;
    gap: 0.5rem;
    background: var(--bg-tertiary);
    border-radius: 10px;
    padding: 0.25rem;
}

.chart-tab,
.filter-btn,
.cat-tab {
    background: transparent;
    border: none;
    color: var(--text-secondary);
    font-family: var(--font-primary);
    font-size: 0.875rem;
    font-weight: 600;
    padding: 0.5rem 1rem;
    border-radius: 8px;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.chart-tab.active,
.filter-btn.active,
.cat-tab.active {
    background: var(--accent-primary);
    color: var(--bg-primary);
}

.chart-container {
    position: relative;
    height: 400px;
}

/* ==================== DATA SECTION ==================== */
.data-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.transactions-panel,
.categories-panel {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 1.5rem;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.panel-header h3 {
    font-size: 1.25rem;
    font-weight: 700;
}

.btn-add {
    background: var(--accent-primary);
    color: var(--bg-primary);
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.btn-add:hover {
    background: var(--accent-secondary);
}

.transaction-filters,
.categories-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    background: var(--bg-tertiary);
    border-radius: 10px;
    padding: 0.25rem;
}

.transactions-list,
.categories-list {
    max-height: 500px;
    overflow-y: auto;
    scrollbar-width: thin;
    scrollbar-color: var(--accent-primary) var(--bg-tertiary);
}

.transactions-list::-webkit-scrollbar,
.categories-list::-webkit-scrollbar {
    width: 8px;
}

.transactions-list::-webkit-scrollbar-track,
.categories-list::-webkit-scrollbar-track {
    background: var(--bg-tertiary);
    border-radius: 4px;
}

.transactions-list::-webkit-scrollbar-thumb,
.categories-list::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: 4px;
}

.transaction-item,
.category-item {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem;
    margin-bottom: 0.75rem;
    transition: all var(--transition-base);
    cursor: pointer;
}

.transaction-item:hover,
.category-item:hover {
    background: var(--bg-elevated);
    border-color: var(--accent-primary);
    transform: translateX(4px);
}

.transaction-header,
.category-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.transaction-description,
.category-name {
    font-weight: 600;
    font-size: 1rem;
}

.transaction-amount {
    font-family: var(--font-mono);
    font-weight: 700;
    font-size: 1.125rem;
}

.transaction-amount.income { color: var(--accent-success); }
.transaction-amount.expense { color: var(--accent-danger); }

.transaction-meta,
.category-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
    font-size: 0.875rem;
    color: var(--text-secondary);
}

.category-progress {
    margin-top: 0.75rem;
}

.progress-bar {
    height: 6px;
    background: var(--bg-primary);
    border-radius: 3px;
    overflow: hidden;
    margin-bottom: 0.25rem;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--accent-primary), var(--accent-secondary));
    border-radius: 3px;
    transition: width var(--transition-slow);
}

.progress-text {
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

/* ==================== MODALS ==================== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal.active {
    display: flex;
    animation: fadeIn var(--transition-base);
}

.modal-content {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    max-width: 500px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    animation: modalSlide var(--transition-slow);
}

@keyframes modalSlide {
    from {
        opacity: 0;
        transform: translateY(30px) scale(0.95);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.ai-modal-content {
    max-width: 700px;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
}

.modal-close {
    width: 32px;
    height: 32px;
    background: var(--bg-tertiary);
    border: none;
    border-radius: 8px;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-close:hover {
    background: var(--accent-danger);
    color: white;
}

.modal-body {
    padding: 1.5rem;
}

.modal-actions {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}

.modal-cancel {
    width: auto;
    flex: 1;
}

/* AI Analysis */
.ai-loading {
    text-align: center;
    padding: 3rem 1rem;
}

.loading-spinner {
    width: 50px;
    height: 50px;
    margin: 0 auto 1rem;
    border: 4px solid var(--bg-tertiary);
    border-top-color: var(--accent-primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.ai-result {
    line-height: 1.8;
}

.ai-result h3 {
    color: var(--accent-primary);
    margin-top: 1.5rem;
    margin-bottom: 0.75rem;
    font-size: 1.125rem;
}

.ai-result p {
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.ai-result ul {
    margin-left: 1.5rem;
    margin-bottom: 1rem;
}

.ai-result li {
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
}

.ai-result strong {
    color: var(--text-primary);
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 1024px) {
    .data-section {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .dashboard {
        padding: 1rem;
    }
    
    .month-navigation {
        flex-direction: column;
        align-items: stretch;
    }
    
    .month-controls {
        justify-content: center;
    }
    
    .btn-close-month {
        width: 100%;
    }
    
    .summary-section {
        grid-template-columns: 1fr;
    }
    
    .header-content {
        padding: 1rem;
    }
    
    .brand-text {
        display: none;
    }
    
    .chart-section {
        padding: 1rem;
    }
    
    .chart-container {
        height: 300px;
    }
    
    .section-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .chart-controls {
        width: 100%;
        flex-wrap: wrap;
    }
    
    .card-value {
        font-size: 1.5rem;
    }
    
    .auth-brand h1 {
        font-size: 2rem;
    }
    
    .brand-icon {
        width: 60px;
        height: 60px;
        font-size: 2rem;
    }
}

@media (max-width: 480px) {
    .transaction-meta,
    .category-meta {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .modal-content {
        margin: 1rem;
    }
    
    .modal-actions {
        flex-direction: column;
    }
    
    .modal-cancel {
        width: 100%;
    }
}

/* Empty States */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-tertiary);
}

.empty-state svg {
    width: 80px;
    height: 80px;
    margin-bottom: 1rem;
    opacity: 0.5;
}

/* Delete Button in Items */
.delete-btn {
    background: var(--bg-primary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    width: 28px;
    height: 28px;
    border-radius: 6px;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.875rem;
}

.delete-btn:hover {
    background: var(--accent-danger);
    border-color: var(--accent-danger);
    color: white;
}