:root {
    --primary: #0f172a;
    --primary-light: #1e293b;
    --accent: #0ea5e9;
    --accent-hover: #0284c7;
    --success: #10b981;
    --warning: #f59e0b;
    --danger: #ef4444;
    --background: #f1f5f9;
    --surface: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --radius: 12px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Outfit', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
    background-color: var(--background);
    color: var(--text-main);
    line-height: 1.5;
    padding: 2rem 1rem;
    min-height: 100-vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary);
    font-weight: 700;
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-muted);
}

/* Settings Panel as a Drawer */
.settings-panel {
    position: fixed;
    top: 0;
    right: -400px;
    width: 380px;
    height: 100vh;
    z-index: 1000;
    background: white;
    box-shadow: -10px 0 30px rgba(0,0,0,0.1);
    transition: var(--transition);
    overflow-y: auto;
    border-radius: 0;
    padding: 2rem;
    margin: 0;
}

.settings-panel.active {
    right: 0;
}

/* Background Overlay when settings open */
.settings-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.2);
    backdrop-filter: blur(4px);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
}

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

.btn-icon {
    position: absolute;
    right: 20px;
    background: white;
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 21px;
    height: 21px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    font-size: 1.5rem;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

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

.dashboard-grid {
    display: grid;
    grid-template-columns: 1fr; /* Single column since settings is now a drawer */
    gap: 2rem;
    align-items: start;
}

@media (max-width: 992px) {
    .dashboard-grid {
        grid-template-columns: 1fr;
    }
}

.card {
    background: var(--surface);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
}

.settings-panel h2 {
    font-size: 1.25rem;
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.form-group {
    margin-bottom: 1.25rem;
}

.form-group label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-main);
}

.form-group input, .form-group select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    transition: all 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.1);
}

.summary-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.summary-card {
    background: var(--surface);
    padding: 1.25rem;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    box-shadow: var(--shadow-sm);
    text-align: center;
}

.summary-card .label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 0.25rem;
    display: block;
}

.summary-card .value {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary);
}

.summary-card.accent {
    border-left: 4px solid var(--accent);
}

.table-container {
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

th {
    background: var(--background);
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.875rem;
    padding: 1rem;
    border-bottom: 2px solid var(--border);
}

td {
    padding: 1rem;
    border-bottom: 1px solid var(--border);
    font-size: 0.9375rem;
}

tr:hover td {
    background: #f1f5f9;
}

/* Center specific columns: Installment and Action/Status */
td:nth-child(2), th:nth-child(2),
td:nth-child(5), th:nth-child(5) {
    text-align: center;
}

/* For History table, Taksit No is 3rd column */
#historyTable td:nth-child(3), #historyTable th:nth-child(3) {
    text-align: center;
}

tr.paid td {
    color: #166534;
    background: #f0fdf4 !important; /* Soft Green */
    text-decoration: none;
}

tr.current-month td {
    background: #f0f9ff !important; /* Soft Blue */
    color: #0369a1;
    font-weight: 600;
}

tr.overdue td {
    background: #fef2f2 !important; /* Soft Red */
    color: #991b1b;
}

.tabs-header {
    display: flex;
    gap: 1rem;
    margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--border);
    padding-bottom: 0.5rem;
}

.tab-btn {
    padding: 0.5rem 1rem;
    border: none;
    background: none;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-muted);
    border-bottom: 2px solid transparent;
    transition: all 0.2s;
}

.tab-btn.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

.tab-content {
    display: none;
}

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

.btn-small {
    padding: 0.25rem 0.5rem;
    font-size: 0.75rem;
    border-radius: 4px;
    width: auto;
}

.btn-success {
    background: var(--success);
    color: white;
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--surface);
    padding: 2rem;
    border-radius: var(--radius);
    width: 100%;
    max-width: 400px;
    box-shadow: var(--shadow);
}

.modal-header {
    margin-bottom: 2.5rem;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

.modal-header h3 {
    font-size: 1.5rem;
    color: var(--primary);
}

.modal-footer {
    display: flex;
    gap: 1rem;
    margin-top: 2rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    gap: 0.5rem;
    width: 100%;
}

.btn-primary {
    background: var(--accent);
    color: white;
}

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

.btn-outline {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-main);
}

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

.mid-payment-item {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 0.5rem;
}

.mid-payment-item input {
    padding: 0.5rem;
}

.badge {
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-success { background: #dcfce7; color: #166534; }

/* Loading State */
.loading-row {
    text-align: center;
    padding: 3rem;
    color: var(--text-muted);
}

.spinner {
    width: 24px;
    height: 24px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    display: inline-block;
    margin-bottom: 0.5rem;
}

/* Login Screen Styles */
.login-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: var(--background);
    backdrop-filter: blur(10px);
    z-index: 9999;
    display: flex;
    align-items: center;
    justify-content: center;
}

.login-box {
    max-width: 400px;
    width: 90%;
    padding: 2.5rem;
    text-align: center;
    animation: fadeIn 0.5s ease;
}

.login-box h2 {
    margin-bottom: 1rem;
    font-size: 1.75rem;
    color: var(--primary);
}

.login-box p {
    color: var(--text-muted);
    margin-bottom: 1.5rem;
}

.login-box input {
    margin-bottom: 1.5rem;
}

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

.app-content {
    transition: var(--transition);
}