:root {
    /* Color Palette */
    --color-primary: hsl(230, 70%, 60%);
    --color-primary-dark: hsl(230, 70%, 50%);
    --color-primary-light: hsl(230, 70%, 95%);
    
    --color-success: hsl(142, 71%, 45%);
    --color-success-light: hsl(142, 71%, 95%);
    
    --color-danger: hsl(0, 84%, 60%);
    --color-danger-light: hsl(0, 84%, 95%);
    
    --color-warning: hsl(45, 93%, 47%);
    --color-warning-light: hsl(45, 93%, 95%);
    
    --color-info: hsl(199, 89%, 48%);
    --color-info-light: hsl(199, 89%, 95%);
    
    /* Neutral Colors */
    --color-bg: hsl(220, 20%, 10%);
    --color-bg-secondary: hsl(220, 18%, 14%);
    --color-bg-tertiary: hsl(220, 16%, 18%);
    --color-surface: hsl(220, 15%, 22%);
    --color-surface-hover: hsl(220, 15%, 26%);
    
    --color-text: hsl(0, 0%, 95%);
    --color-text-secondary: hsl(0, 0%, 70%);
    --color-text-tertiary: hsl(0, 0%, 50%);
    
    --color-border: hsl(220, 15%, 30%);
    --color-border-light: hsl(220, 15%, 25%);
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, hsl(230, 70%, 60%), hsl(260, 70%, 60%));
    --gradient-success: linear-gradient(135deg, hsl(142, 71%, 45%), hsl(162, 71%, 45%));
    --gradient-danger: linear-gradient(135deg, hsl(0, 84%, 60%), hsl(20, 84%, 60%));
    --gradient-surface: linear-gradient(135deg, hsl(220, 15%, 22%), hsl(220, 15%, 18%));
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-xl: 1.5rem;
    
    /* 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(99, 102, 241, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 2rem;
    --font-size-4xl: 2.5rem;
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Navigation */
.navbar {
    background: var(--color-bg-secondary);
    border-bottom: 1px solid var(--color-border-light);
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(10px);
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 var(--spacing-xl);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    font-size: var(--font-size-xl);
    font-weight: 700;
}

.logo-icon {
    width: 32px;
    height: 32px;
    color: var(--color-primary);
}

.brand-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: var(--spacing-sm);
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    background: transparent;
    border: none;
    color: var(--color-text-secondary);
    font-size: var(--font-size-base);
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-md);
    transition: all var(--transition-base);
}

.nav-link svg {
    width: 20px;
    height: 20px;
    stroke-width: 2;
}

.nav-link:hover {
    background: var(--color-surface);
    color: var(--color-text);
}

.nav-link.active {
    background: var(--gradient-primary);
    color: white;
}

/* Container */
.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-2xl) var(--spacing-xl);
}

/* Page Header */
.page-header {
    margin-bottom: var(--spacing-2xl);
}

.page-header h1 {
    font-size: var(--font-size-4xl);
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    color: var(--color-text-secondary);
    font-size: var(--font-size-lg);
}

/* Page Visibility */
.page {
    display: none;
}

.page.active {
    display: block;
    animation: fadeIn var(--transition-base);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Summary Cards */
.summary-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.summary-card {
    background: var(--gradient-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    display: flex;
    align-items: center;
    gap: var(--spacing-lg);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.summary-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: var(--gradient-primary);
    opacity: 0;
    transition: opacity var(--transition-base);
}

.summary-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.summary-card:hover::before {
    opacity: 1;
}

.income-card::before {
    background: var(--gradient-success);
}

.expense-card::before {
    background: var(--gradient-danger);
}

.card-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.card-icon svg {
    width: 28px;
    height: 28px;
    stroke-width: 2;
}

.income-icon {
    background: var(--color-success-light);
    color: var(--color-success);
}

.expense-icon {
    background: var(--color-danger-light);
    color: var(--color-danger);
}

.balance-icon {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

.card-content {
    flex: 1;
}

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

.card-value {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.card-change {
    font-size: var(--font-size-sm);
    font-weight: 600;
}

.card-change.positive {
    color: var(--color-success);
}

.card-change.negative {
    color: var(--color-danger);
}

/* Charts Grid */
.charts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-2xl);
}

.chart-card {
    background: var(--gradient-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    transition: all var(--transition-base);
}

.chart-card:hover {
    box-shadow: var(--shadow-md);
}

.chart-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.chart-header h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.chart-filter {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    color: var(--color-text);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.chart-filter:hover {
    background: var(--color-surface-hover);
}

.chart-container {
    position: relative;
    height: 300px;
}

/* Recent Transactions */
.recent-transactions {
    background: var(--gradient-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
}

.section-header h2,
.section-header h3 {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.btn-link {
    background: none;
    border: none;
    color: var(--color-primary);
    font-size: var(--font-size-sm);
    font-weight: 600;
    cursor: pointer;
    transition: color var(--transition-fast);
}

.btn-link:hover {
    color: var(--color-primary-dark);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-2xl);
    color: var(--color-text-secondary);
}

.empty-state svg {
    width: 64px;
    height: 64px;
    margin-bottom: var(--spacing-md);
    stroke-width: 1.5;
    opacity: 0.5;
}

.empty-state p {
    margin-bottom: var(--spacing-lg);
    font-size: var(--font-size-lg);
}

/* Buttons */
.btn-primary {
    background: var(--gradient-primary);
    color: white;
    border: none;
    padding: var(--spacing-sm) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md), var(--shadow-glow);
}

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

.btn-primary svg {
    width: 20px;
    height: 20px;
    stroke-width: 2;
}

.btn-secondary {
    background: var(--color-surface);
    color: var(--color-text);
    border: 1px solid var(--color-border);
    padding: var(--spacing-sm) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.btn-secondary:hover {
    background: var(--color-surface-hover);
}

/* Form Card */
.form-card {
    background: var(--gradient-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    margin-bottom: var(--spacing-2xl);
}

.form-card h2 {
    font-size: var(--font-size-2xl);
    font-weight: 600;
    margin-bottom: var(--spacing-lg);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.form-group {
    display: flex;
    flex-direction: column;
}

.form-group.full-width {
    grid-column: 1 / -1;
}

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

.form-group input,
.form-group select {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    color: var(--color-text);
    padding: var(--spacing-sm) var(--spacing-md);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-base);
    font-family: var(--font-family);
    transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.form-group input::placeholder {
    color: var(--color-text-tertiary);
}

/* Type Toggle */
.type-toggle {
    display: flex;
    gap: var(--spacing-sm);
}

.type-btn {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-md);
    background: var(--color-surface);
    border: 2px solid var(--color-border);
    color: var(--color-text-secondary);
    border-radius: var(--radius-md);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
}

.type-btn svg {
    width: 20px;
    height: 20px;
    stroke-width: 2;
}

.type-btn:hover {
    background: var(--color-surface-hover);
}

.type-btn.active[data-type="expense"] {
    background: var(--color-danger-light);
    border-color: var(--color-danger);
    color: var(--color-danger);
}

.type-btn.active[data-type="income"] {
    background: var(--color-success-light);
    border-color: var(--color-success);
    color: var(--color-success);
}

.form-actions {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
}

/* Transactions Card */
.transactions-card {
    background: var(--gradient-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
}

.filter-controls {
    display: flex;
    gap: var(--spacing-sm);
}

.filter-select {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    color: var(--color-text);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-sm);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.filter-select:hover {
    background: var(--color-surface-hover);
}

/* Transactions Table */
.transactions-table-container {
    overflow-x: auto;
    margin-top: var(--spacing-lg);
}

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

.transactions-table thead {
    background: var(--color-surface);
    border-bottom: 2px solid var(--color-border);
}

.transactions-table th {
    padding: var(--spacing-md);
    text-align: left;
    font-size: var(--font-size-sm);
    font-weight: 600;
    color: var(--color-text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.transactions-table td {
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border-light);
}

.transactions-table tbody tr {
    transition: background var(--transition-fast);
}

.transactions-table tbody tr:hover {
    background: var(--color-surface);
}

.transaction-type {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    font-size: var(--font-size-xs);
    font-weight: 600;
}

.transaction-type.income {
    background: var(--color-success-light);
    color: var(--color-success);
}

.transaction-type.expense {
    background: var(--color-danger-light);
    color: var(--color-danger);
}

.transaction-category {
    font-size: var(--font-size-sm);
}

.transaction-amount {
    font-weight: 600;
    font-size: var(--font-size-base);
}

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

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

.text-right {
    text-align: right;
}

.text-center {
    text-align: center;
}

.btn-delete {
    background: transparent;
    border: none;
    color: var(--color-danger);
    cursor: pointer;
    padding: var(--spacing-xs);
    border-radius: var(--radius-sm);
    transition: all var(--transition-fast);
}

.btn-delete:hover {
    background: var(--color-danger-light);
}

.btn-delete svg {
    width: 18px;
    height: 18px;
    stroke-width: 2;
}

/* Transactions List (Dashboard) */
.transactions-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.transaction-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    padding: var(--spacing-md);
    background: var(--color-surface);
    border: 1px solid var(--color-border-light);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
}

.transaction-item:hover {
    background: var(--color-surface-hover);
    transform: translateX(4px);
}

.transaction-icon {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: var(--font-size-lg);
    flex-shrink: 0;
}

.transaction-icon.income {
    background: var(--color-success-light);
}

.transaction-icon.expense {
    background: var(--color-danger-light);
}

.transaction-details {
    flex: 1;
}

.transaction-description {
    font-weight: 600;
    margin-bottom: 2px;
}

.transaction-meta {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: var(--spacing-lg) var(--spacing-md);
    }
    
    .summary-grid {
        grid-template-columns: 1fr;
    }
    
    .charts-grid {
        grid-template-columns: 1fr;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .nav-links {
        flex-direction: column;
        width: 100%;
    }
    
    .page-header h1 {
        font-size: var(--font-size-3xl);
    }
    
    .filter-controls {
        flex-direction: column;
    }
}

/* Loading Animation */
@keyframes pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

.loading {
    animation: pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}