/**
 * India Income Tax Calculator — FY 2025-26
 * Enhanced UI with Inter font, improved color palette, and modern design.
 */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

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

:root {
    --primary-color: #1a56db;
    --primary-dark: #1240a8;
    --primary-light: #ebf1ff;
    --secondary-color: #1e2a3a;
    --background-color: #f0f4f8;
    --card-background: #ffffff;
    --text-color: #1e2a3a;
    --text-light: #64748b;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --border-focus: #1a56db;
    --error-color: #dc2626;
    --error-light: #fef2f2;
    --success-color: #16a34a;
    --success-light: #f0fdf4;
    --warning-color: #d97706;
    --warning-light: #fffbeb;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08), 0 2px 4px rgba(0, 0, 0, 0.04);
    --shadow-hover: 0 8px 24px rgba(26, 86, 219, 0.14), 0 4px 8px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 12px 32px rgba(0, 0, 0, 0.12);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-xs: 6px;
    --transition: all 0.2s ease;
}

/* ─── Dark Mode ──────────────────────────────────────────────────────────── */

[data-theme="dark"] {
    --primary-color: #4d8ef0;
    --primary-dark: #3a7ae0;
    --primary-light: rgba(77, 142, 240, 0.12);
    --secondary-color: #e2e8f0;
    --background-color: #0f1623;
    --card-background: #1a2232;
    --text-color: #e2e8f0;
    --text-light: #94a3b8;
    --text-muted: #64748b;
    --border-color: #2a3a52;
    --border-focus: #4d8ef0;
    --error-color: #f87171;
    --error-light: rgba(248, 113, 113, 0.1);
    --success-color: #4ade80;
    --success-light: rgba(74, 222, 128, 0.1);
    --warning-color: #fbbf24;
    --warning-light: rgba(251, 191, 36, 0.1);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3), 0 1px 2px rgba(0, 0, 0, 0.2);
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.3), 0 2px 4px rgba(0, 0, 0, 0.2);
    --shadow-hover: 0 8px 24px rgba(77, 142, 240, 0.2), 0 4px 8px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.5);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 24px 16px;
    min-height: 100vh;
    font-size: 15px;
}

.container {
    max-width: 820px;
    margin: 0 auto;
    background-color: var(--card-background);
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    overflow: hidden;
}

/* ─── Header ─────────────────────────────────────────────────────────────── */

header {
    background: linear-gradient(140deg, #1240a8 0%, #1a56db 50%, #2563eb 100%);
    color: white;
    padding: 44px 36px 40px;
    text-align: center;
    position: relative;
    overflow: visible;
}

header::before {
    content: '';
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse at 70% 0%, rgba(255,255,255,0.12) 0%, transparent 60%),
                radial-gradient(ellipse at 20% 100%, rgba(255,140,0,0.15) 0%, transparent 50%);
    pointer-events: none;
    border-radius: inherit;
}

header::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, #ff9933 33.33%, white 33.33% 66.66%, #138808 66.66%);
    opacity: 0.7;
}

/* ─── Theme Toggle ───────────────────────────────────────────────────────── */

.theme-toggle {
    position: absolute;
    top: 16px;
    right: 16px;
    background: rgba(255, 255, 255, 0.15);
    border: 1px solid rgba(255, 255, 255, 0.25);
    border-radius: 20px;
    padding: 6px 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 4px;
    font-size: 1rem;
    transition: background 0.2s ease, border-color 0.2s ease;
    line-height: 1;
}

.theme-toggle:hover {
    background: rgba(255, 255, 255, 0.25);
    border-color: rgba(255, 255, 255, 0.4);
}

/* Show/hide icons based on theme */
.theme-icon-dark { display: none; }
.theme-icon-light { display: inline; }

[data-theme="dark"] .theme-icon-dark { display: inline; }
[data-theme="dark"] .theme-icon-light { display: none; }

.header-badge {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    background: rgba(255, 255, 255, 0.18);
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(8px);
    border-radius: 20px;
    padding: 5px 14px;
    font-size: 0.78rem;
    font-weight: 500;
    letter-spacing: 0.4px;
    margin-bottom: 16px;
    text-transform: uppercase;
}

header h1 {
    font-size: 2.4rem;
    margin-bottom: 10px;
    font-weight: 700;
    letter-spacing: -0.5px;
    line-height: 1.2;
}

.subtitle {
    font-size: 1.05rem;
    opacity: 0.88;
    font-weight: 400;
}

/* ─── Main ───────────────────────────────────────────────────────────────── */

main {
    padding: 36px 32px;
}

.intro-box {
    text-align: center;
    margin-bottom: 32px;
    padding: 18px 24px;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
    border: 1px solid rgba(77, 142, 240, 0.15);
}

.intro-box p {
    color: var(--text-color);
    font-size: 0.95rem;
    line-height: 1.65;
    max-width: 680px;
    margin: 0 auto;
}

/* ─── Mode Toggle ────────────────────────────────────────────────────────── */

.calculator-section {
    margin-bottom: 36px;
}

.mode-toggle {
    display: flex;
    gap: 0;
    margin-bottom: 28px;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 0;
}

.mode-btn {
    background: none;
    border: none;
    padding: 10px 22px;
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-light);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: var(--transition);
    position: relative;
    top: 2px;
    font-family: inherit;
    letter-spacing: 0.1px;
}

.mode-btn:hover {
    color: var(--primary-color);
    background: var(--primary-light);
    border-radius: 6px 6px 0 0;
}

.mode-btn.active {
    color: var(--primary-color);
    border-bottom-color: var(--primary-color);
}

/* ─── Form ───────────────────────────────────────────────────────────────── */

.comparison-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 28px;
    margin-bottom: 24px;
}

.comparison-column h3 {
    color: var(--secondary-color);
    margin-bottom: 18px;
    font-size: 1.15rem;
    font-weight: 600;
    text-align: center;
}

.comparison-column h5 {
    color: var(--secondary-color);
    margin-bottom: 12px;
    font-size: 0.95rem;
    font-weight: 600;
    text-align: center;
}

.compare-shared {
    display: flex;
    flex-wrap: wrap;
    gap: 18px;
    align-items: flex-start;
}

.tax-form {
    display: flex;
    flex-direction: column;
    gap: 18px;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.form-group label {
    font-weight: 600;
    color: var(--secondary-color);
    font-size: 0.875rem;
    letter-spacing: 0.1px;
}

.form-group input,
.form-group select {
    padding: 11px 14px;
    border: 1.5px solid var(--border-color);
    border-radius: var(--radius-xs);
    font-size: 0.95rem;
    transition: var(--transition);
    font-family: inherit;
    color: var(--text-color);
    background: var(--card-background);
}

@media screen and (max-width: 768px) {
    .form-group input,
    .form-group select {
        font-size: 16px;
    }
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px rgba(26, 86, 219, 0.12);
}

.form-group input:hover:not(:focus),
.form-group select:hover:not(:focus) {
    border-color: #94a3b8;
}

.form-group input.input-error,
.form-group input.input-error:hover {
    border-color: var(--error-color);
    background-color: var(--error-light);
}

.form-group input.input-error:focus {
    border-color: var(--error-color);
    box-shadow: 0 0 0 3px rgba(220, 38, 38, 0.12);
}

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

.hint {
    font-size: 0.775rem;
    color: var(--text-light);
    line-height: 1.4;
}

.error-message {
    color: var(--error-color);
    font-size: 0.8rem;
    min-height: 16px;
    display: flex;
    align-items: center;
    gap: 4px;
}

.error-message:not(:empty)::before {
    content: '⚠';
    font-size: 0.75rem;
}

.section-label {
    font-weight: 600;
    color: var(--secondary-color);
    font-size: 0.85rem;
    margin-top: 6px;
    margin-bottom: 2px;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.form-group-inline {
    flex-direction: row;
    flex-wrap: wrap;
    align-items: center;
    gap: 10px;
}

.form-group-inline input[type="checkbox"] {
    width: 18px;
    height: 18px;
    margin: 0;
    accent-color: var(--primary-color);
    cursor: pointer;
}

.form-group-inline label {
    flex: 1;
    min-width: 120px;
    margin-bottom: 0;
    cursor: pointer;
}

.old-regime-fields {
    padding: 16px;
    border: 1.5px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--background-color);
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.employee-deductions {
    padding: 16px;
    border: 1.5px solid var(--border-color);
    border-radius: var(--radius-sm);
    background: var(--background-color);
    display: flex;
    flex-direction: column;
    gap: 14px;
}

/* ─── Calculate Button ───────────────────────────────────────────────────── */

.calculate-btn {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
    border: none;
    padding: 14px 32px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    margin-top: 8px;
    font-family: inherit;
    letter-spacing: 0.2px;
    box-shadow: 0 2px 8px rgba(26, 86, 219, 0.3);
}

.calculate-btn:hover {
    background: linear-gradient(135deg, #1647c5 0%, #0f3590 100%);
    transform: translateY(-1px);
    box-shadow: 0 6px 16px rgba(26, 86, 219, 0.35);
}

.calculate-btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 6px rgba(26, 86, 219, 0.25);
}

/* ─── Form Actions Row ───────────────────────────────────────────────────── */

.form-actions {
    display: flex;
    gap: 12px;
    align-items: center;
    margin-top: 8px;
}

.form-actions .calculate-btn {
    margin-top: 0;
    flex: 1;
}

/* ─── Clear Button ───────────────────────────────────────────────────────── */

.clear-btn {
    background: transparent;
    color: var(--text-light);
    border: 1.5px solid var(--border-color);
    padding: 14px 20px;
    font-size: 0.95rem;
    font-weight: 600;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: var(--transition);
    font-family: inherit;
    white-space: nowrap;
}

.clear-btn:hover {
    border-color: var(--error-color);
    color: var(--error-color);
    background: var(--error-light);
}

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

/* ─── Results Section ────────────────────────────────────────────────────── */

.results-section {
    background: var(--background-color);
    border-radius: var(--radius);
    padding: 28px;
    margin-top: 28px;
    border: 1px solid var(--border-color);
    animation: slideIn 0.35s ease;
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(12px); }
    to   { opacity: 1; transform: translateY(0); }
}

.results-section h2 {
    color: var(--secondary-color);
    margin-bottom: 22px;
    font-size: 1.6rem;
    font-weight: 700;
    text-align: center;
    letter-spacing: -0.3px;
}

/* ─── Regime Compare Banner ─────────────────────────────────────────────── */

.regime-compare-banner {
    display: none;
    background: linear-gradient(135deg, var(--warning-light), #fef9ee);
    border: 1px solid rgba(217, 119, 6, 0.25);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    margin-bottom: 20px;
    font-size: 0.875rem;
    color: var(--secondary-color);
    align-items: center;
    gap: 10px;
}

.regime-compare-banner.visible {
    display: flex;
}

.regime-compare-banner .banner-icon {
    font-size: 1.1rem;
    flex-shrink: 0;
}

.regime-compare-banner strong {
    color: var(--warning-color);
}

/* ─── Results Tabs ───────────────────────────────────────────────────────── */

.results-tabs {
    display: flex;
    flex-wrap: nowrap;
    gap: 0;
    margin-bottom: 24px;
    border-bottom: 2px solid var(--border-color);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
}

.results-tabs::-webkit-scrollbar { display: none; }

.tab-btn {
    background: none;
    border: none;
    padding: 10px 18px;
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-light);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: var(--transition);
    position: relative;
    top: 2px;
    white-space: nowrap;
    flex-shrink: 0;
    font-family: inherit;
    letter-spacing: 0.1px;
}

.tab-btn:hover {
    color: var(--primary-color);
    background: var(--primary-light);
    border-radius: 6px 6px 0 0;
}

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

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
    animation: fadeIn 0.2s ease;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to   { opacity: 1; }
}

.tab-content h3 {
    color: var(--secondary-color);
    margin-bottom: 18px;
    font-size: 1.15rem;
    font-weight: 600;
    text-align: center;
}

/* ─── Results Grid ───────────────────────────────────────────────────────── */

.results-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
    gap: 16px;
}

.result-item {
    background-color: var(--card-background);
    padding: 18px 20px;
    border-radius: var(--radius-sm);
    border: 1.5px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 8px;
    transition: var(--transition);
}

.result-item:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
    border-color: rgba(26, 86, 219, 0.2);
}

.result-item.net-income {
    border-color: var(--success-color);
    background: var(--success-light);
    grid-column: 1 / -1;
}

.result-item.net-income:hover {
    border-color: var(--success-color);
    box-shadow: 0 6px 20px rgba(22, 163, 74, 0.15);
}

.result-label {
    font-size: 0.75rem;
    color: var(--text-light);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.7px;
}

.result-value {
    font-size: 1.7rem;
    font-weight: 700;
    color: var(--text-color);
    letter-spacing: -0.5px;
    line-height: 1.1;
}

.result-value.tax-deduction {
    color: var(--error-color);
}

.result-item.net-income .result-value {
    color: var(--success-color);
    font-size: 2rem;
}

/* ─── Comparison Tab ─────────────────────────────────────────────────────── */

.comparison-section {
    margin-bottom: 28px;
}

.comparison-section h4 {
    color: var(--secondary-color);
    margin-bottom: 16px;
    font-size: 1.05rem;
    font-weight: 600;
    text-align: center;
    border-bottom: 1.5px solid var(--border-color);
    padding-bottom: 10px;
}

.comparison-results-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
    margin-bottom: 24px;
}

.comparison-difference {
    margin-top: 24px;
    padding-top: 24px;
    border-top: 2px solid var(--border-color);
}

.comparison-difference h4 {
    color: var(--secondary-color);
    margin-bottom: 18px;
    text-align: center;
    border: none;
    padding: 0;
    font-size: 1.05rem;
    font-weight: 600;
}

/* ─── Breakdown Tab ──────────────────────────────────────────────────────── */

.breakdown-section {
    margin-bottom: 28px;
}

.breakdown-section h4 {
    color: var(--secondary-color);
    margin-bottom: 14px;
    font-size: 1rem;
    font-weight: 600;
}

.breakdown-table {
    width: 100%;
    border-collapse: collapse;
    background-color: var(--card-background);
    border-radius: var(--radius-sm);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1.5px solid var(--border-color);
    font-size: 0.9rem;
}

.breakdown-table thead {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: white;
}

.breakdown-table th {
    padding: 11px 16px;
    text-align: left;
    font-weight: 600;
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.6px;
}

.breakdown-table td {
    padding: 11px 16px;
    border-bottom: 1px solid var(--border-color);
    color: var(--text-color);
}

.breakdown-table tbody tr:last-child td {
    border-bottom: none;
}

.breakdown-table tbody tr:hover {
    background-color: var(--primary-light);
}

.result-card {
    background-color: var(--card-background);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin-bottom: 16px;
    box-shadow: var(--shadow-sm);
    border: 1.5px solid var(--border-color);
}

.result-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 0;
    border-bottom: 1px solid var(--border-color);
    font-size: 0.9rem;
    gap: 12px;
}

.result-row:last-child {
    border-bottom: none;
}

.result-row span:last-child {
    font-weight: 600;
    text-align: right;
    flex-shrink: 0;
}

/* ─── Pie Chart ──────────────────────────────────────────────────────────── */

.pie-chart-container {
    margin-top: 4px;
    margin-bottom: 24px;
    padding: 20px;
    background: var(--card-background);
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
    border: 1.5px solid var(--border-color);
}

.pie-chart-container h4 {
    margin: 0 0 16px;
    font-size: 1rem;
    font-weight: 600;
    color: var(--secondary-color);
    text-align: center;
}

.pie-chart-wrap {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 28px;
}

.pie-chart-wrap canvas {
    display: block;
    max-width: 100%;
    height: auto;
}

.pie-legend {
    display: flex;
    flex-direction: column;
    gap: 12px;
    font-size: 0.875rem;
    color: var(--text-color);
}

.pie-legend-item {
    display: flex;
    align-items: center;
    gap: 10px;
}

.pie-legend-dot {
    width: 12px;
    height: 12px;
    border-radius: 50%;
    flex-shrink: 0;
}

/* ─── Slabs / Collapsible ────────────────────────────────────────────────── */

.slabs-reference,
.deductions-info {
    margin-top: 28px;
    padding-top: 20px;
    border-top: 1.5px solid var(--border-color);
}

.slabs-toggle {
    width: 100%;
    padding: 12px 16px;
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--primary-color);
    background: var(--primary-light);
    border: 1.5px solid rgba(26, 86, 219, 0.2);
    border-radius: var(--radius-sm);
    cursor: pointer;
    text-align: left;
    transition: var(--transition);
    font-family: inherit;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.slabs-toggle:hover {
    border-color: var(--primary-color);
    background: rgba(26, 86, 219, 0.06);
}

.slabs-toggle::after {
    content: '▾';
    font-size: 0.85rem;
    transition: transform 0.2s ease;
    flex-shrink: 0;
}

.slabs-toggle[aria-expanded="true"]::after {
    transform: rotate(180deg);
}

.slabs-content {
    margin-top: 14px;
}

.slabs-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

.slabs-table-wrap h4 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--secondary-color);
    margin-bottom: 8px;
}

.slabs-note {
    font-size: 0.76rem;
    color: var(--text-light);
    margin-top: 8px;
    line-height: 1.4;
}

/* ─── Info Cards ─────────────────────────────────────────────────────────── */

.info-card {
    background: var(--card-background);
    border: 1.5px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin-bottom: 12px;
}

.info-card:last-child { margin-bottom: 0; }

.info-card h4 {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--secondary-color);
    margin-bottom: 6px;
}

.info-card p {
    font-size: 0.875rem;
    color: var(--text-light);
    line-height: 1.55;
}

/* ─── Misc ───────────────────────────────────────────────────────────────── */

.disclaimer {
    font-size: 0.775rem;
    color: var(--text-muted);
    margin-top: 20px;
    font-style: italic;
    text-align: center;
}

footer {
    padding: 18px 28px;
    background: var(--background-color);
    border-top: 1px solid var(--border-color);
}

footer p {
    font-size: 0.775rem;
    color: var(--text-light);
    line-height: 1.5;
    text-align: center;
}

/* ─── Responsive ─────────────────────────────────────────────────────────── */

@media (max-width: 700px) {
    body { padding: 10px 8px; }
    header { padding: 36px 20px 26px; }
    header h1 { font-size: 1.65rem; }
    .subtitle { font-size: 0.9rem; }
    main { padding: 20px 16px; }
    .comparison-container,
    .comparison-results-grid,
    .slabs-grid {
        grid-template-columns: 1fr;
    }
    .results-grid {
        grid-template-columns: 1fr;
    }
    .results-section { padding: 18px 14px; }
    .old-regime-fields,
    .employee-deductions { padding: 14px 12px; }
    .result-value { font-size: 1.5rem; }
    .result-item.net-income .result-value { font-size: 1.7rem; }
    .form-actions { flex-direction: row; }
    .theme-toggle { top: 12px; right: 12px; padding: 5px 10px; font-size: 0.9rem; }
}

/* ─── Print ──────────────────────────────────────────────────────────────── */

@media print {
    body { background: #fff; padding: 0; }
    .calculator-section,
    .mode-toggle,
    .slabs-reference,
    .deductions-info,
    .results-tabs,
    .regime-compare-banner,
    .theme-toggle { display: none !important; }
    .tab-content { display: none !important; }
    .tab-content.active { display: block !important; }
    .container { box-shadow: none; }
    .results-section { background: white; border: none; }
    /* Force light mode for print regardless of theme */
    [data-theme="dark"] { --background-color: #fff; --card-background: #fff; --text-color: #1e2a3a; --border-color: #e2e8f0; }
}