/* ============================================
   RESET & BASE STYLES
   ============================================ */

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

:root {
    /* Color Palette */
    --primary-color: #2563eb;      /* Blue */
    --primary-dark: #1d4ed8;
    --secondary-color: #10b981;    /* Green */
    --secondary-dark: #059669;
    --danger-color: #ef4444;       /* Red */
    --danger-dark: #dc2626;
    --warning-color: #f59e0b;      /* Orange */
    
    /* Category Colors */
    --color-food: #f59e0b;
    --color-transport: #3b82f6;
    --color-entertainment: #a855f7;
    --color-shopping: #ec4899;
    --color-bills: #eab308;
    --color-health: #10b981;
    --color-other: #6b7280;
    
    /* Neutral Colors */
    --bg-primary: #f9fafb;
    --bg-secondary: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    
    /* Spacing */
    --spacing-xs: 8px;
    --spacing-sm: 12px;
    --spacing-md: 16px;
    --spacing-lg: 24px;
    --spacing-xl: 32px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
        'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
        sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    padding: var(--spacing-lg);
    color: var(--text-primary);
}

/* ============================================
   CONTAINER
   ============================================ */

.container {
    max-width: 1200px;
    margin: 0 auto;
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

/* ============================================
   HEADER
   ============================================ */

.header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-lg);
}

.header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-sm);
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.9;
    font-weight: 300;
}

/* ============================================
   SUMMARY CARDS
   ============================================ */

.summary-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
    padding: var(--spacing-xl);
    background: var(--bg-primary);
}

.card {
    background: var(--bg-secondary);
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: transform 0.2s, box-shadow 0.2s;
}

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

.card h3 {
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: var(--spacing-sm);
}

.card .amount {
    color: var(--primary-color);
    font-size: 2rem;
    font-weight: 700;
}

.card .count {
    color: var(--secondary-color);
    font-size: 2.5rem;
    font-weight: 700;
}

/* ============================================
   CATEGORY BREAKDOWN
   ============================================ */

.category-breakdown {
    padding: var(--spacing-xl);
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
}

.category-breakdown h2 {
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1.5rem;
}

.category-bars {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.category-bar-item {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

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

.category-info {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.category-emoji {
    font-size: 1.5rem;
}

.category-name {
    font-weight: 600;
    color: var(--text-primary);
    text-transform: capitalize;
}

.category-amount {
    font-weight: 700;
    color: var(--text-secondary);
}

.category-percentage {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 600;
}

.bar-container {
    width: 100%;
    height: 12px;
    background: var(--border-color);
    border-radius: 6px;
    overflow: hidden;
}

.bar-fill {
    height: 100%;
    border-radius: 6px;
    transition: width 0.6s ease-out;
    background: linear-gradient(90deg, var(--bar-color) 0%, var(--bar-color-light) 100%);
}

/* Category-specific colors for bars */
.bar-food {
    --bar-color: #f59e0b;
    --bar-color-light: #fbbf24;
}

.bar-transport {
    --bar-color: #3b82f6;
    --bar-color-light: #60a5fa;
}

.bar-entertainment {
    --bar-color: #a855f7;
    --bar-color-light: #c084fc;
}

.bar-shopping {
    --bar-color: #ec4899;
    --bar-color-light: #f472b6;
}

.bar-bills {
    --bar-color: #eab308;
    --bar-color-light: #facc15;
}

.bar-health {
    --bar-color: #10b981;
    --bar-color-light: #34d399;
}

.bar-other {
    --bar-color: #6b7280;
    --bar-color-light: #9ca3af;
}

/* ============================================
   FORM CONTAINER
   ============================================ */

.form-container {
    padding: var(--spacing-xl);
    border-bottom: 1px solid var(--border-color);
}

.form-container h2 {
    color: var(--text-primary);
    margin-bottom: var(--spacing-lg);
    font-size: 1.5rem;
}

#expense-form {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-md);
}

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

label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--spacing-xs);
}

input,
select {
    padding: 12px 16px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    font-size: 1rem;
    transition: border-color 0.2s, box-shadow 0.2s;
    background: var(--bg-secondary);
    color: var(--text-primary);
}

input:focus,
select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

input::placeholder {
    color: var(--text-secondary);
    opacity: 0.5;
}

/* ============================================
   BUTTONS
   ============================================ */

button {
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-primary {
    background: var(--secondary-color);
    color: white;
    grid-column: 1 / -1;
    padding: 16px;
    font-size: 1.1rem;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    background: var(--secondary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

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

.btn-delete {
    background: transparent;
    color: var(--danger-color);
    padding: 8px 12px;
    font-size: 1.5rem;
    transition: all 0.2s;
}

.btn-delete:hover {
    background: var(--danger-color);
    color: white;
    transform: scale(1.1);
}

.btn-clear {
    background: var(--danger-color);
    color: white;
    padding: 8px 16px;
    font-size: 0.875rem;
}

.btn-clear:hover {
    background: var(--danger-dark);
}

.btn-export {
    background: var(--primary-color);
    color: white;
    padding: 8px 16px;
    font-size: 0.875rem;
}

.btn-export:hover {
    background: var(--primary-dark);
}
/* ============================================
   INSIGHTS SECTION
   ============================================ */

.insights-section {
    padding: var(--spacing-xl);
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.insights-section h2 {
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1.5rem;
}

.insights-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
}

.insight-card {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: var(--spacing-lg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-md);
}

.insight-card h4 {
    font-size: 0.875rem;
    opacity: 0.9;
    margin-bottom: var(--spacing-sm);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.insight-value {
    font-size: 1.75rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

.insight-description {
    font-size: 0.875rem;
    opacity: 0.8;
}
/* ============================================
   FILTER SECTION
   ============================================ */

.filter-container {
    padding: var(--spacing-lg) var(--spacing-xl);
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
}

.filter-container h3 {
    margin-bottom: var(--spacing-md);
    color: var(--text-primary);
}

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

.btn-filter {
    padding: 10px 20px;
    background: var(--bg-secondary);
    color: var(--text-secondary);
    border: 2px solid var(--border-color);
    font-size: 0.875rem;
    transition: all 0.2s;
}

.btn-filter:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
}

.btn-filter.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* ============================================
   EXPENSES LIST
   ============================================ */

.expenses-container {
    padding: var(--spacing-xl);
}

.expenses-container h2 {
    margin-bottom: var(--spacing-lg);
    color: var(--text-primary);
    font-size: 1.5rem;
}

.expenses-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.empty-state {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* ============================================
   EXPENSE CARDS
   ============================================ */

.expense-card {
    display: grid;
    grid-template-columns: auto 1fr auto auto;
    gap: var(--spacing-md);
    align-items: center;
    padding: var(--spacing-lg);
    background: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: all 0.2s;
    animation: slideIn 0.3s ease-out;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

.expense-icon {
    font-size: 2.5rem;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-primary);
    border-radius: var(--radius-md);
}

.expense-details {
    flex: 1;
}

.expense-details h4 {
    font-size: 1.1rem;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.expense-category {
    font-size: 0.875rem;
    color: var(--text-secondary);
    text-transform: capitalize;
    margin-bottom: 2px;
}

.expense-date {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

.expense-amount {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

/* ============================================
   RESPONSIVE DESIGN
   ============================================ */

@media (max-width: 768px) {
    body {
        padding: var(--spacing-sm);
    }
    
    .header h1 {
        font-size: 2rem;
    }
    
    .summary-cards {
        grid-template-columns: 1fr;
        padding: var(--spacing-lg);
    }
    
    #expense-form {
        grid-template-columns: 1fr;
    }
    
    .filter-buttons {
        justify-content: center;
    }
    
    .expense-card {
        grid-template-columns: auto 1fr;
        gap: var(--spacing-sm);
    }
    
    .expense-amount {
        grid-column: 1 / -1;
        text-align: center;
        padding-top: var(--spacing-sm);
        border-top: 1px solid var(--border-color);
    }
    
    .btn-delete {
        grid-column: 1 / -1;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.75rem;
    }
    
    .card .amount,
    .card .count {
        font-size: 1.75rem;
    }
}

/* ============================================
   UTILITY CLASSES
   ============================================ */

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

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