:root {
    --bg-dark: #252936;
    --bg-light: #f5f6fa;
    --primary: #4a69ff;
    --primary-hover: #3c54cc;
    --secondary: #313541;
    --border: #e1e4e8;
    --text-light: #f8f9fa;
    --text-dark: #343a40;
    --text-muted: #6c757d;
    --danger: #dc3545;
    --success: #20c997;
    --warning: #ffc107;
    --info: #17a2b8;
    --white: #fff;
    --shadow: 0 2px 4px rgba(0,0,0,0.05);
}
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--bg-light);
    color: var(--text-dark);
}
.app-container {
    width: 100%;
    min-height: 100vh;
}

/* --- Main Content --- */
.main-content {
    padding: 25px;
    overflow-y: auto;
}
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}
.page-header h1 {
    font-size: 1.75rem;
    color: var(--text-dark);
}
.header-actions {
    display: flex;
    gap: 10px;
    align-items: center;
}
.btn {
    padding: 8px 16px;
    border: none;
    border-radius: 5px;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
}
.btn-primary {
    background-color: var(--primary);
    color: var(--white);
}
.btn-primary:hover { background-color: var(--primary-hover); }
.card {
    background: var(--white);
    border-radius: 6px;
    border: 1px solid var(--border);
    padding: 20px;
    box-shadow: var(--shadow);
}
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
    margin-bottom: 20px;
}
.stat-card h3 {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 5px;
    text-transform: uppercase;
}
.stat-card .stat-value {
    font-size: 2rem;
    font-weight: 600;
}
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 15px;
}
th, td {
    text-align: left;
    padding: 12px 10px;
    border-bottom: 1px solid var(--border);
    font-size: 0.9rem;
}
th {
    font-size: 0.8rem;
    text-transform: uppercase;
    color: var(--text-muted);
    font-weight: 600;
}
tr:last-child td { border-bottom: none; }
.amount { text-align: right; font-weight: 500; }
.amount.positive { color: var(--success); }
.amount.negative { color: var(--danger); }
.actions { display: flex; gap: 8px; justify-content: flex-end; }
.btn-sm {
    padding: 4px 8px;
    font-size: 0.8rem;
    border-radius: 4px;
}
.btn-warning { background-color: #fff3cd; color: #664d03; border: 1px solid #ffc107; }
.btn-info { background-color: #d1ecf1; color: #0c5460; border: 1px solid #17a2b8; }
.btn-danger { background-color: #f8d7da; color: #58151c; border: 1px solid #dc3545; }

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    pointer-events: none;
}

/* --- Modal (Compact) --- */
.modal-overlay {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background: rgba(0,0,0,0.4);
    display: none;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}
.modal-overlay.active { display: flex; }
.modal-content {
    background: var(--white);
    padding: 25px;
    border-radius: 6px;
    width: 90%;
    max-width: 450px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}
.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}
.modal-header h2 { font-size: 1.25rem; }
.close-btn { background: none; border: none; font-size: 1.5rem; cursor: pointer; color: var(--text-muted); }
.form { display: flex; flex-direction: column; gap: 15px; }
.form-group { display: flex; flex-direction: column; }
.form-group label { margin-bottom: 5px; font-weight: 500; font-size: 0.9rem; }
.form-group input, .form-group select, .form-group textarea {
    padding: 10px;
    border: 1px solid #ced4da;
    border-radius: 4px;
    font-size: 0.9rem;
    font-family: inherit;
}
.form-group textarea {
    resize: vertical;
    min-height: 80px;
}
.form-group small {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 4px;
}
.form-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 10px; }
.btn-secondary { background-color: #e9ecef; color: var(--text-dark); }

/* Checkbox styling */
input[type="checkbox"] {
    width: 16px;
    height: 16px;
    cursor: pointer;
    accent-color: var(--primary);
}

/* Select all checkbox header */
th:first-child {
    width: 40px;
    text-align: center;
}

/* Individual transaction checkboxes */
td:first-child {
    text-align: center;
    width: 40px;
}

/* Merge form styling */
.merge-summary {
    max-height: 200px;
    overflow-y: auto;
    margin-bottom: 15px;
    border: 1px solid var(--border);
    border-radius: 4px;
    padding: 10px;
}

.merge-summary-item {
    padding: 8px;
    margin: 4px 0;
    background: #f8f9fa;
    border-radius: 4px;
    font-size: 0.9rem;
    border-left: 3px solid var(--primary);
}

.merge-total {
    padding: 10px;
    background: #e3f2fd;
    border-radius: 4px;
    font-weight: 500;
    border: 1px solid #bbdefb;
}

/* Split form styling */
.split-form-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 15px;
}

.split-original {
    padding: 10px;
    background: #f8f9fa;
    border-radius: 4px;
    margin-bottom: 15px;
    border-left: 3px solid var(--info);
}

.split-preview {
    padding: 10px;
    background: #e3f2fd;
    border-radius: 4px;
    margin: 10px 0;
    border: 1px solid #bbdefb;
}

/* Spending Overview Styling */
.spending-breakdown-mini {
    margin-top: 10px;
    padding-top: 10px;
    border-top: 1px solid var(--border);
}

.category-spending-mini {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 4px 0;
    font-size: 0.8rem;
}

.category-name-mini {
    color: var(--text-muted);
    font-weight: 400;
}

.category-amount-mini {
    color: var(--danger);
    font-weight: 500;
}

/* Chart Styling */
.chart-container {
    position: relative;
    height: 400px;
    margin-top: 20px;
}

.chart-controls {
    display: flex;
    align-items: center;
    gap: 10px;
}

.chart-select {
    padding: 6px 12px;
    border: 1px solid var(--border);
    border-radius: 4px;
    font-size: 0.9rem;
    background-color: var(--white);
    cursor: pointer;
}

.chart-select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 2px rgba(74, 105, 255, 0.2);
}

/* Card header styling for charts */
.card-header h2 {
    font-size: 1.25rem;
    color: var(--text-dark);
    margin: 0;
}

/* Chart Tabs Styling */
.chart-tabs {
    margin-top: 20px;
}

.tab-buttons {
    display: flex;
    border-bottom: 1px solid var(--border);
    margin-bottom: 20px;
}

.tab-button {
    padding: 12px 20px;
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
    transition: all 0.2s ease;
}

.tab-button:hover {
    color: var(--text-dark);
    background-color: rgba(74, 105, 255, 0.05);
}

.tab-button.active {
    color: var(--primary);
    border-bottom-color: var(--primary);
    background-color: rgba(74, 105, 255, 0.1);
}

.tab-content {
    position: relative;
}

.tab-pane {
    display: none;
}

.tab-pane.active {
    display: block;
}