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

:root {
    --navy: #1a365d;
    --blue: #2c5282;
    --blue-light: #3182ce;
    --bg: #f7fafc;
    --white: #ffffff;
    --gray-100: #f1f5f9;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e1;
    --gray-500: #64748b;
    --gray-700: #334155;
    --gray-900: #0f172a;
    --green: #16a34a;
    --green-light: #dcfce7;
    --red: #dc2626;
    --red-light: #fef2f2;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-lg: 0 4px 12px rgba(0,0,0,0.1);
    --radius: 8px;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    color: var(--gray-900);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    background: linear-gradient(135deg, var(--navy), var(--blue));
    color: white;
    padding: 16px 24px;
    box-shadow: var(--shadow-lg);
}
.header-content {
    max-width: 1500px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo { display: flex; align-items: center; gap: 12px; }
.logo-icon {
    width: 44px; height: 44px;
    background: rgba(255,255,255,0.15);
    border-radius: 10px;
    display: flex; align-items: center; justify-content: center;
    font-size: 22px; font-weight: 700;
}
.logo h1 { font-size: 22px; font-weight: 700; }
.tagline { font-size: 13px; opacity: 0.8; }
.tax-year-badge {
    background: rgba(255,255,255,0.15);
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 13px;
    font-weight: 600;
}

/* Tab Bar */
.tab-bar {
    background: white;
    display: flex;
    max-width: 1500px;
    margin: 0 auto;
    width: 100%;
    border-bottom: 2px solid var(--gray-200);
    padding: 0 24px;
}
.tab {
    padding: 14px 24px;
    border: none;
    background: none;
    font-size: 15px;
    font-weight: 500;
    color: var(--gray-500);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
    transition: all 0.2s;
}
.tab:hover { color: var(--blue); }
.tab.active { color: var(--navy); border-bottom-color: var(--navy); font-weight: 600; }

/* Main */
main {
    flex: 1;
    max-width: 1500px;
    margin: 0 auto;
    width: 100%;
    padding: 20px 24px;
}
.tab-content { display: none; }
.tab-content.active { display: block; }

/* Chat */
.chat-wrap { max-width: 960px; margin: 0 auto; }
.chat-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 16px;
}
.mode-toggle {
    display: flex;
    background: var(--gray-100);
    border-radius: 8px;
    padding: 3px;
}
.mode-btn {
    padding: 8px 20px;
    border: none;
    background: none;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    color: var(--gray-500);
    transition: all 0.2s;
}
.mode-btn.active { background: var(--navy); color: white; }

.chat-messages {
    background: white;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    height: calc(100vh - 280px);
    min-height: 400px;
    overflow-y: auto;
    padding: 20px;
    margin-bottom: 16px;
}
.message { margin-bottom: 16px; display: flex; }
.message.user { justify-content: flex-end; }
.message-content {
    max-width: 85%;
    padding: 14px 18px;
    border-radius: 12px;
    font-size: 14px;
    line-height: 1.6;
}
.message.bot .message-content {
    background: var(--gray-100);
    border-bottom-left-radius: 4px;
    line-height: 1.45;
}
.message.bot .message-content p { margin: 0 0 2px 0; }
.message.bot .message-content p:last-child { margin-bottom: 0; }
.message.bot .message-content br { margin: 0; line-height: 0.6; }
.message.bot .message-content br + br { display: none; }
.message.bot .message-content h3,
.message.bot .message-content h4 {
    color: var(--navy);
    margin: 6px 0 2px 0;
    font-size: 14px;
}
.message.bot .message-content h3:first-child,
.message.bot .message-content h4:first-child { margin-top: 0; }
.message.bot .message-content ul,
.message.bot .message-content ol {
    margin: 2px 0;
    padding-left: 18px;
}
.message.bot .message-content li { margin: 0; line-height: 1.4; }
.message.bot .message-content code {
    background: rgba(0,0,0,0.06);
    padding: 1px 5px;
    border-radius: 3px;
    font-size: 13px;
}
.message.bot .message-content table {
    border-collapse: collapse;
    margin: 6px 0;
    font-size: 13px;
    width: 100%;
}
.message.bot .message-content th,
.message.bot .message-content td {
    border: 1px solid var(--gray-200);
    padding: 5px 10px;
    text-align: left;
}
.message.bot .message-content th {
    background: var(--gray-200);
    font-weight: 600;
}
.message.user .message-content {
    background: var(--navy);
    color: white;
    border-bottom-right-radius: 4px;
}
.suggestions { list-style: none; margin-top: 8px; }
.suggestion {
    color: var(--blue-light);
    cursor: pointer;
    padding: 4px 0;
    font-size: 13px;
}
.suggestion:hover { text-decoration: underline; }
.typing-indicator {
    display: flex; gap: 4px; padding: 8px 0;
}
.typing-indicator span {
    width: 8px; height: 8px;
    background: var(--gray-300);
    border-radius: 50%;
    animation: bounce 1.4s infinite ease-in-out;
}
.typing-indicator span:nth-child(2) { animation-delay: 0.2s; }
.typing-indicator span:nth-child(3) { animation-delay: 0.4s; }
@keyframes bounce {
    0%, 80%, 100% { transform: scale(0); }
    40% { transform: scale(1); }
}

.chat-input-area {
    display: flex;
    gap: 12px;
}
#chat-input {
    flex: 1;
    padding: 12px 16px;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    font-size: 14px;
    resize: none;
    font-family: inherit;
}
#chat-input:focus { outline: none; border-color: var(--blue); box-shadow: 0 0 0 3px rgba(44,82,130,0.1); }

/* Buttons */
.btn-primary {
    background: var(--navy);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}
.btn-primary:hover { background: var(--blue); }
.btn-primary:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-secondary {
    background: white;
    color: var(--navy);
    border: 1px solid var(--gray-200);
    padding: 12px 24px;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
}
.btn-secondary:hover { background: var(--gray-100); }
.btn-sm { padding: 6px 14px; font-size: 13px; }
.btn-lg { padding: 14px 28px; font-size: 15px; }
.btn-row { display: flex; gap: 12px; margin-top: 16px; }

/* ─── Calculator Page Layout ─────────────────────────────────── */
.calc-page-layout {
    display: flex;
    gap: 0;
    align-items: flex-start;
}

/* ─── Sidebar ────────────────────────────────────────────────── */
.calc-sidebar {
    width: 210px;
    flex-shrink: 0;
    background: white;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    margin-right: 20px;
    position: sticky;
    top: 20px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
    transition: width 0.2s;
}

.sidebar-collapse-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    padding: 8px 12px;
    background: var(--gray-100);
    border: none;
    border-bottom: 1px solid var(--gray-200);
    font-size: 16px;
    color: var(--gray-500);
    cursor: pointer;
    font-weight: 700;
    transition: background 0.15s, transform 0.2s;
    border-radius: var(--radius) var(--radius) 0 0;
}
.sidebar-collapse-btn:hover { background: var(--gray-200); color: var(--navy); }

.calc-sidebar.collapsed {
    width: 36px;
}
.calc-sidebar.collapsed .sidebar-inner { display: none; }
.calc-sidebar.collapsed .sidebar-collapse-btn {
    border-radius: var(--radius);
    border-bottom: none;
    transform: rotate(180deg);
    writing-mode: vertical-lr;
    height: 100%;
    min-height: 80px;
}

.sidebar-inner { padding: 4px 0 8px; }

.sidebar-section {
    padding: 10px 12px 6px;
    border-bottom: 1px solid var(--gray-200);
}
.sidebar-section:last-child { border-bottom: none; }

.sidebar-section-label {
    font-size: 10px;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    color: var(--gray-500);
    margin-bottom: 8px;
}

.preset-btn, .faq-btn {
    display: block;
    width: 100%;
    text-align: left;
    padding: 7px 10px;
    margin-bottom: 4px;
    border: 1px solid var(--gray-200);
    border-radius: 6px;
    background: var(--gray-100);
    font-size: 12px;
    color: var(--gray-700);
    cursor: pointer;
    transition: background 0.15s, border-color 0.15s;
    line-height: 1.3;
}
.preset-btn:hover {
    background: var(--navy);
    color: white;
    border-color: var(--navy);
}
.faq-btn {
    background: white;
    color: var(--blue-light);
    border-color: var(--gray-200);
}
.faq-btn:hover {
    background: var(--blue-light);
    color: white;
    border-color: var(--blue-light);
}

/* ─── Calc Main ──────────────────────────────────────────────── */
.calc-main {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.calc-form {
    background: white;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    padding: 20px 24px 24px;
}

.calc-form-header {
    margin-bottom: 16px;
}
.calc-form-header h2 { font-size: 20px; color: var(--navy); margin-bottom: 2px; }
.form-subtitle { font-size: 13px; color: var(--gray-500); }

/* Top bar (filing status + entity type) */
.form-top-bar {
    display: flex;
    gap: 16px;
    margin-bottom: 16px;
}
.form-top-bar .form-group {
    width: 260px;
    margin-bottom: 0;
}
.form-top-bar--2col .form-group {
    flex: 1;
    width: auto;
}

/* ─── Form Fields Grid ───────────────────────────────────────── */
.form-fields-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin-bottom: 0;
}
.form-fields-grid fieldset {
    border: 1px solid var(--gray-200);
    border-radius: var(--radius);
    padding: 14px 16px 16px;
    margin: 0;
}
.form-fields-grid fieldset.span-2 {
    grid-column: span 2;
}
.form-fields-grid fieldset.span-3 {
    grid-column: 1 / -1;
}

legend {
    padding: 0 8px;
    font-weight: 600;
    font-size: 13px;
    color: var(--navy);
}

/* ─── Fieldset internal grid ─────────────────────────────────── */
.fieldset-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
    margin-top: 10px;
}
.fieldset-body .form-group {
    margin-bottom: 0;
}
.fieldset-body .form-group.full-width {
    grid-column: 1 / -1;
}

/* Itemized deductions sub-grid */
#itemized-fields {
    grid-column: 1 / -1;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 10px;
}
#itemized-fields .form-group {
    margin-bottom: 0;
}

/* General form */
.form-group { margin-bottom: 12px; }
.form-group label {
    display: block;
    font-size: 12px;
    font-weight: 500;
    color: var(--gray-700);
    margin-bottom: 4px;
}
.form-group select,
.form-group input[type="number"] {
    width: 100%;
    padding: 8px 10px;
    border: 1px solid var(--gray-200);
    border-radius: 6px;
    font-size: 13px;
    font-family: inherit;
}
.form-group select:focus,
.form-group input:focus { outline: none; border-color: var(--blue); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.form-hint { display: block; font-size: 11px; color: var(--gray-500); margin-top: 3px; }
.checkbox-group label { display: flex; align-items: center; gap: 8px; cursor: pointer; font-size: 13px; }
.checkbox-group input[type="checkbox"] { width: auto; }

/* ─── Results ────────────────────────────────────────────────── */
.calc-results {
    background: white;
    border-radius: var(--radius);
    border: 1px solid var(--gray-200);
    padding: 24px;
}
.results-placeholder {
    text-align: center;
    padding: 40px 20px;
    color: var(--gray-500);
}

.results-section { margin-bottom: 24px; }
.results-section h3 {
    font-size: 15px;
    color: var(--navy);
    margin-bottom: 10px;
    padding-bottom: 6px;
    border-bottom: 2px solid var(--gray-200);
}
.line-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 5px 0;
    font-size: 13px;
}
.line-item.subtotal {
    border-top: 1px solid var(--gray-200);
    font-weight: 600;
    padding-top: 8px;
    margin-top: 4px;
}
.line-item.total {
    border-top: 2px solid var(--navy);
    font-weight: 700;
    font-size: 15px;
    padding-top: 10px;
    margin-top: 6px;
    color: var(--navy);
}
.line-item .label { color: var(--gray-700); }
.line-item .amount { font-variant-numeric: tabular-nums; }
.line-item .amount.negative { color: var(--green); }
.line-item .amount.positive { color: var(--gray-900); }
.line-item .note {
    font-size: 11px;
    color: var(--gray-500);
    margin-left: 8px;
}

.summary-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    margin-bottom: 20px;
}
.summary-card {
    background: var(--gray-100);
    border-radius: 8px;
    padding: 14px;
    text-align: center;
}
.summary-card .label { font-size: 11px; color: var(--gray-500); text-transform: uppercase; letter-spacing: 0.5px; }
.summary-card .value { font-size: 22px; font-weight: 700; color: var(--navy); margin-top: 4px; }
.summary-card.highlight { background: var(--navy); }
.summary-card.highlight .label { color: rgba(255,255,255,0.7); }
.summary-card.highlight .value { color: white; }

/* Results layout — two columns for breakdown sections */
.results-body {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 24px;
}
.results-body .results-section { margin-bottom: 0; }
.results-body .results-section.full-width {
    grid-column: 1 / -1;
}

/* Entity comparison table */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 13px;
    margin-top: 12px;
}
.comparison-table th, .comparison-table td {
    padding: 9px 12px;
    text-align: right;
    border-bottom: 1px solid var(--gray-200);
}
.comparison-table th { background: var(--gray-100); font-weight: 600; color: var(--navy); text-align: left; }
.comparison-table th:not(:first-child) { text-align: right; }
.comparison-table td:first-child { text-align: left; font-weight: 500; }
.comparison-table tr.best td { background: var(--green-light); }

/* Validation */
.form-group input.invalid,
.form-group select.invalid {
    border-color: var(--red);
    background: var(--red-light);
}
.form-group .validation-msg {
    font-size: 11px;
    color: var(--red);
    margin-top: 2px;
    display: none;
}
.form-group .validation-msg.visible { display: block; }
.form-group .validation-warning {
    font-size: 11px;
    color: #b45309;
    margin-top: 2px;
    display: none;
}
.form-group .validation-warning.visible { display: block; }

/* ─── AI CTA Button ──────────────────────────────────────────── */
.ai-cta-btn {
    display: block;
    width: 100%;
    margin-top: 20px;
    padding: 13px 24px;
    background: linear-gradient(135deg, var(--navy) 0%, var(--blue-light) 100%);
    color: white;
    border: none;
    border-radius: var(--radius);
    font-size: 14px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s, transform 0.15s;
    text-align: center;
    letter-spacing: 0.2px;
}
.ai-cta-btn:hover {
    opacity: 0.92;
    transform: translateY(-1px);
}

/* Disclaimer modal */
.disclaimer-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.65);
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 16px;
}
.disclaimer-overlay.hidden { display: none; }
.disclaimer-modal {
    background: white;
    border-radius: var(--radius);
    max-width: 680px;
    width: 100%;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}
.disclaimer-modal h2 {
    background: linear-gradient(135deg, var(--navy), var(--blue));
    color: white;
    padding: 18px 24px;
    font-size: 16px;
    font-weight: 600;
    border-radius: var(--radius) var(--radius) 0 0;
    flex-shrink: 0;
}
.disclaimer-body {
    padding: 20px 24px;
    overflow-y: auto;
    font-size: 13px;
    color: var(--gray-700);
    line-height: 1.6;
    flex: 1;
}
.disclaimer-body p { margin-bottom: 12px; }
.disclaimer-body ol {
    padding-left: 20px;
    display: flex;
    flex-direction: column;
    gap: 10px;
}
.disclaimer-body ol li { line-height: 1.55; }
.disclaimer-actions {
    padding: 16px 24px;
    border-top: 1px solid var(--gray-200);
    display: flex;
    justify-content: flex-end;
    flex-shrink: 0;
}
.chat-disclaimer {
    font-size: 11px;
    color: var(--gray-500);
    text-align: center;
    padding: 6px 12px 0;
    line-height: 1.4;
}

/* Footer */
footer {
    background: white;
    border-top: 1px solid var(--gray-200);
    padding: 14px 24px;
    font-size: 11px;
    color: var(--gray-500);
    text-align: center;
}
.footer-disclaimer {
    max-width: 960px;
    margin: 0 auto 6px;
    line-height: 1.5;
}
.footer-meta { color: var(--gray-500); }
.footer-meta a { color: var(--blue-light); text-decoration: none; }
.footer-meta a:hover { text-decoration: underline; }

/* Responsive */
@media (max-width: 1100px) {
    .form-fields-grid { grid-template-columns: 1fr 1fr; }
    .form-fields-grid fieldset.span-2 { grid-column: span 2; }
    .summary-grid { grid-template-columns: 1fr 1fr; }
    .results-body { grid-template-columns: 1fr; }
}
@media (max-width: 768px) {
    .calc-page-layout { flex-direction: column; }
    .calc-sidebar { width: 100%; position: static; margin-right: 0; margin-bottom: 16px; }
    .calc-sidebar.collapsed { width: 100%; }
    .form-fields-grid { grid-template-columns: 1fr; }
    .form-fields-grid fieldset.span-2 { grid-column: span 1; }
    .fieldset-body { grid-template-columns: 1fr; }
    #itemized-fields { grid-template-columns: 1fr; }
    .form-top-bar { flex-direction: column; gap: 12px; }
    .form-top-bar .form-group { width: 100%; }
    .header-content { flex-direction: column; gap: 8px; }
    .tab { padding: 12px 16px; font-size: 13px; }
    .chat-messages { height: 400px; }
    .message-content { max-width: 90%; }
    .summary-grid { grid-template-columns: 1fr 1fr; }
}