/* Tariff Impact Analyzer — Stylesheet */

:root {
    --color-bg: #09090b;
    --color-surface: #18181b;
    --color-surface-light: #27272a;
    --color-border: rgba(255,255,255,0.08);
    --color-border-hover: rgba(255,255,255,0.15);
    --color-primary: #3b82f6;
    --color-primary-hover: #2563eb;
    --color-primary-light: #60a5fa;
    --color-primary-subtle: rgba(59,130,246,0.1);
    --color-accent: #10b981;
    --color-accent-dark: #059669;
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-danger: #ef4444;
    --color-text: #fafafa;
    --color-text-secondary: #a1a1aa;
    --color-text-muted: #71717a;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'SF Mono', 'Cascadia Code', 'JetBrains Mono', monospace;
    --radius-sm: 6px;
    --radius: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
    --shadow: 0 1px 3px rgba(0,0,0,0.4);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.3);
    --transition: 0.15s ease;
}

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

body {
    font-family: var(--font-sans);
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

a { color: var(--color-primary-light); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Layout ─────────────────────────────────────────────────────────────── */

.container { max-width: 1100px; margin: 0 auto; padding: 2rem 1.5rem; }
.landing-container { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }

/* ── Buttons ────────────────────────────────────────────────────────────── */

.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 0.5rem;
    padding: 0.75rem 1.25rem; font-size: 0.9375rem; font-weight: 600; font-family: inherit;
    background: var(--color-primary); color: #fff; border: none; border-radius: var(--radius);
    cursor: pointer; transition: background var(--transition), opacity var(--transition);
    text-decoration: none; white-space: nowrap; line-height: 1.4;
}
.btn:hover { background: var(--color-primary-hover); text-decoration: none; }
.btn:active { opacity: 0.9; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; }
.btn-secondary {
    background: transparent; border: 1px solid var(--color-border-hover);
    color: var(--color-text-secondary);
}
.btn-secondary:hover { background: var(--color-surface-light); color: var(--color-text); }
.btn-primary { background: var(--color-primary); color: #fff; }
.btn-accent { background: var(--color-accent); color: #fff; }
.btn-accent:hover { background: var(--color-accent-dark); }
.btn-success { background: var(--color-success); color: #fff; }
.btn-success:hover { background: #059669; }
.btn-danger { background: transparent; border: 1px solid var(--color-danger); color: var(--color-danger); }
.btn-danger:hover { background: var(--color-danger); color: #fff; }
.btn-full { width: 100%; }
.btn-large { padding: 0.875rem 1.75rem; font-size: 1rem; }
.btn-group { display: flex; gap: 0.75rem; flex-wrap: wrap; }

/* ── Navigation ─────────────────────────────────────────────────────────── */

.nav {
    display: flex; justify-content: space-between; align-items: center;
    padding: 1.25rem 0; border-bottom: 1px solid var(--color-border);
}
.nav-logo {
    font-size: 1.125rem; font-weight: 700; color: var(--color-text);
    text-decoration: none; display: flex; align-items: center; gap: 0.375rem;
    letter-spacing: -0.01em;
}
.nav-logo span { color: var(--color-primary); }
.nav-links { display: flex; gap: 1.75rem; align-items: center; }
.nav-links a {
    color: var(--color-text-muted); text-decoration: none; font-size: 0.875rem;
    font-weight: 500; transition: color var(--transition);
}
.nav-links a:hover { color: var(--color-text); }
.nav-buttons { display: flex; gap: 0.75rem; align-items: center; }
.nav-mobile-menu { display: none; }

/* ── Hero ───────────────────────────────────────────────────────────────── */

.hero { padding: 5rem 0 3.5rem; text-align: center; }
.hero-badge {
    display: inline-block; padding: 0.375rem 0.875rem;
    background: var(--color-primary-subtle); border: 1px solid rgba(59,130,246,0.2);
    border-radius: 2rem; color: var(--color-primary-light); font-size: 0.8125rem;
    font-weight: 500; margin-bottom: 1.5rem;
}
.hero h1 {
    font-size: 3rem; font-weight: 800; line-height: 1.1;
    margin-bottom: 1.25rem; color: var(--color-text);
    letter-spacing: -0.025em;
}
.hero-subtitle {
    font-size: 1.125rem; color: var(--color-text-secondary);
    max-width: 560px; margin: 0 auto 2rem; line-height: 1.7;
}
.hero-buttons { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; }

/* ── Section Headers ───────────────────────────────────────────────────── */

.section-header { text-align: center; margin-bottom: 3rem; }
.section-header h2 {
    font-size: 2rem; font-weight: 700; margin-bottom: 0.75rem;
    letter-spacing: -0.02em;
}
.section-header p {
    color: var(--color-text-secondary); font-size: 1rem;
    max-width: 520px; margin: 0 auto;
}

/* ── Try It Now ─────────────────────────────────────────────────────────── */

.try-it { padding: 3.5rem 0; }
.try-it-card {
    background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-xl); padding: 2rem;
}
.try-form-grid {
    display: grid; grid-template-columns: 1fr 1fr 1fr 1fr; gap: 1rem;
    margin-bottom: 1.25rem;
}
.try-form-desc { grid-column: 1 / -1; }
.try-submit-btn { width: 100%; }

.try-loading { text-align: center; padding: 2rem; color: var(--color-text-muted); }
.try-error {
    background: rgba(239,68,68,0.1); border: 1px solid rgba(239,68,68,0.2);
    color: var(--color-danger); padding: 0.875rem 1rem; border-radius: var(--radius);
    margin-top: 1rem; font-size: 0.9rem;
}

.try-signup-prompt { margin-top: 1.5rem; }
.try-signup-card {
    background: var(--color-surface); border: 1px solid var(--color-primary);
    border-radius: var(--radius); padding: 1.5rem; text-align: center;
}
.try-signup-card h3 { margin: 0 0 0.5rem; color: var(--color-text); font-size: 1.15rem; }
.try-signup-card p { margin: 0 0 1.25rem; color: var(--color-text-secondary); font-size: 0.9rem; }
.try-signup-actions { display: flex; gap: 0.75rem; justify-content: center; flex-wrap: wrap; }
.try-signup-actions .btn { font-size: 0.9rem; }

.try-results { margin-top: 1.5rem; }
.try-results-header {
    display: flex; justify-content: space-between; align-items: center;
    margin-bottom: 1.25rem; flex-wrap: wrap; gap: 0.75rem;
}
.try-hts-info { font-family: var(--font-mono); font-size: 0.85rem; color: var(--color-text-secondary); }
.try-results-grid {
    display: grid; grid-template-columns: repeat(auto-fit, minmax(140px, 1fr)); gap: 0.75rem;
    margin-bottom: 1.25rem;
}
.try-metric {
    background: var(--color-surface-light); padding: 1rem;
    border-radius: var(--radius); text-align: center;
}
.try-metric-value { font-size: 1.25rem; font-weight: 700; font-family: var(--font-mono); }
.try-metric-label {
    font-size: 0.6875rem; color: var(--color-text-muted); text-transform: uppercase;
    letter-spacing: 0.05em; margin-top: 0.25rem;
}
.try-cta {
    display: flex; align-items: center; gap: 1rem;
    justify-content: center; flex-wrap: wrap; padding-top: 0.5rem;
}
.try-cta-hint { color: var(--color-text-muted); font-size: 0.8125rem; }

/* ── How It Works ──────────────────────────────────────────────────────── */

.how-it-works { padding: 4rem 0; }
.steps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.5rem; }
.step-card {
    background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-lg); padding: 1.75rem; text-align: center;
}
.step-number {
    width: 40px; height: 40px; background: var(--color-primary); color: #fff;
    border-radius: 50%; display: inline-flex; align-items: center; justify-content: center;
    font-size: 1rem; font-weight: 700; margin-bottom: 1rem;
}
.step-card h3 { font-size: 1.0625rem; margin-bottom: 0.5rem; font-weight: 600; }
.step-card p { color: var(--color-text-secondary); font-size: 0.875rem; line-height: 1.6; }

/* ── Problem / Solution ────────────────────────────────────────────────── */

.problem-solution {
    padding: 4rem 0; display: grid;
    grid-template-columns: 1fr 1fr; gap: 1.5rem;
}
.problem-card, .solution-card {
    padding: 2rem; border-radius: var(--radius-lg);
    background: var(--color-surface); border: 1px solid var(--color-border);
}
.problem-card { border-color: rgba(239,68,68,0.15); }
.solution-card { border-color: rgba(16,185,129,0.15); }
.card-icon {
    width: 40px; height: 40px; border-radius: var(--radius);
    display: flex; align-items: center; justify-content: center;
    margin-bottom: 1rem; font-size: 0.875rem; font-weight: 700;
}
.problem-card .card-icon {
    background: rgba(239,68,68,0.1); color: var(--color-danger);
}
.solution-card .card-icon {
    background: rgba(16,185,129,0.1); color: var(--color-success);
}
.card-title { font-size: 1.125rem; font-weight: 700; margin-bottom: 0.75rem; }
.card-text { color: var(--color-text-secondary); font-size: 0.9rem; }
.card-list { list-style: none; margin-top: 1.25rem; }
.card-list li {
    padding: 0.375rem 0; display: flex; align-items: flex-start; gap: 0.625rem;
    color: var(--color-text-secondary); font-size: 0.875rem;
}
.card-list-bad li::before { content: "\00d7"; color: var(--color-danger); font-weight: 700; font-size: 1rem; }
.card-list-good li::before { content: "\2713"; color: var(--color-success); font-weight: 700; }

/* ── Features ──────────────────────────────────────────────────────────── */

.features { padding: 4rem 0; }
.features-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1.25rem; }
.feature-card {
    padding: 1.5rem; background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-lg); transition: border-color var(--transition);
}
.feature-card:hover { border-color: var(--color-border-hover); }
.feature-icon {
    width: 40px; height: 40px; background: var(--color-primary-subtle);
    border-radius: var(--radius); display: flex; align-items: center;
    justify-content: center; margin-bottom: 1rem;
}
.feature-icon svg { width: 20px; height: 20px; stroke: var(--color-primary-light); fill: none; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.feature-title { font-size: 0.9375rem; font-weight: 600; margin-bottom: 0.375rem; }
.feature-desc { color: var(--color-text-secondary); font-size: 0.8125rem; line-height: 1.6; }

/* ── Pricing ───────────────────────────────────────────────────────────── */

.pricing { padding: 4rem 0; }
.pricing-grid {
    display: grid; grid-template-columns: repeat(3, 1fr);
    gap: 1.25rem; max-width: 960px; margin: 0 auto;
}
.pricing-card {
    background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-lg); padding: 2rem; position: relative;
}
.pricing-card.featured { border-color: rgba(59,130,246,0.3); }
.pricing-badge {
    position: absolute; top: -10px; left: 50%; transform: translateX(-50%);
    background: var(--color-primary); color: #fff; padding: 0.25rem 0.75rem;
    border-radius: 1rem; font-size: 0.6875rem; font-weight: 600; text-transform: uppercase;
    letter-spacing: 0.03em;
}
.pricing-name { font-size: 1.25rem; font-weight: 700; margin-bottom: 0.25rem; }
.pricing-desc { color: var(--color-text-muted); font-size: 0.8125rem; margin-bottom: 1.25rem; }
.pricing-price { display: flex; align-items: baseline; gap: 0.125rem; margin-bottom: 1.25rem; }
.pricing-amount { font-size: 2.5rem; font-weight: 800; letter-spacing: -0.02em; }
.pricing-period { color: var(--color-text-muted); font-size: 0.875rem; }
.pricing-features { list-style: none; margin-bottom: 1.5rem; }
.pricing-features li {
    padding: 0.5rem 0; display: flex; align-items: center; gap: 0.625rem;
    color: var(--color-text-secondary); font-size: 0.8125rem;
    border-bottom: 1px solid var(--color-border);
}
.pricing-features li:last-child { border-bottom: none; }
.pricing-features li::before { content: "\2713"; color: var(--color-success); font-weight: 600; }

/* ── FAQ ───────────────────────────────────────────────────────────────── */

.faq { padding: 4rem 0; }
.faq-grid {
    display: grid; grid-template-columns: 1fr 1fr;
    gap: 1rem; max-width: 880px; margin: 0 auto;
}
.faq-item {
    background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-lg); padding: 1.25rem;
}
.faq-question { font-size: 0.9375rem; font-weight: 600; margin-bottom: 0.5rem; }
.faq-answer { color: var(--color-text-secondary); font-size: 0.8125rem; line-height: 1.6; }

/* ── CTA ───────────────────────────────────────────────────────────────── */

.cta { padding: 4rem 0; text-align: center; }
.cta-box {
    background: var(--color-surface); border: 1px solid rgba(59,130,246,0.15);
    border-radius: var(--radius-xl); padding: 3.5rem 2rem;
}
.cta h2 { font-size: 2rem; font-weight: 700; margin-bottom: 0.75rem; letter-spacing: -0.02em; }
.cta p { color: var(--color-text-secondary); font-size: 1rem; max-width: 440px; margin: 0 auto 1.5rem; }

/* ── Footer ────────────────────────────────────────────────────────────── */

.footer { padding: 2.5rem 0; border-top: 1px solid var(--color-border); text-align: center; }
.footer-links { display: flex; justify-content: center; gap: 1.5rem; margin-bottom: 1rem; flex-wrap: wrap; }
.footer-links a { color: var(--color-text-muted); text-decoration: none; font-size: 0.8125rem; }
.footer-links a:hover { color: var(--color-text); }
.footer-copy { color: var(--color-text-muted); font-size: 0.75rem; }

footer { text-align: center; padding: 2rem; color: var(--color-text-muted); font-size: 0.8125rem; }
footer a { color: var(--color-primary-light); text-decoration: none; }
footer a:hover { text-decoration: underline; }

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

.dashboard-header {
    display: flex; justify-content: space-between; align-items: center;
    padding: 1rem 0; border-bottom: 1px solid var(--color-border); margin-bottom: 1.5rem;
}
.user-info { display: flex; align-items: center; gap: 0.75rem; }
.user-email { font-weight: 500; font-size: 0.875rem; }
.tier-badge {
    display: inline-block; padding: 0.2rem 0.625rem; border-radius: 1rem;
    font-size: 0.6875rem; font-weight: 600; text-transform: uppercase; letter-spacing: 0.03em;
}
.tier-badge.free { background: var(--color-surface-light); color: var(--color-text-muted); }
.tier-badge.pro { background: rgba(59,130,246,0.15); color: #60a5fa; }
.tier-badge.team { background: rgba(245,158,11,0.15); color: #fbbf24; }
.logout-btn {
    background: transparent; color: var(--color-text-muted); border: 1px solid var(--color-border);
    padding: 0.4rem 0.875rem; border-radius: var(--radius); cursor: pointer;
    font-size: 0.8125rem; font-family: inherit; transition: var(--transition);
}
.logout-btn:hover { background: var(--color-surface-light); color: var(--color-text); }
.subtitle { color: var(--color-text-muted); font-size: 0.875rem; }

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

.tabs {
    display: flex; gap: 0; margin-bottom: 1.5rem;
    border-bottom: 1px solid var(--color-border);
}
.tab-btn {
    padding: 0.625rem 1.25rem; background: transparent; border: none;
    color: var(--color-text-muted); font-size: 0.875rem; font-weight: 500;
    cursor: pointer; border-bottom: 2px solid transparent; margin-bottom: -1px;
    transition: var(--transition); font-family: inherit;
}
.tab-btn:hover { color: var(--color-text-secondary); }
.tab-btn.active { color: var(--color-primary-light); border-bottom-color: var(--color-primary); }
.tab-content { display: none; }
.tab-content.active { display: block; }

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

.card {
    background: var(--color-surface); border: 1px solid var(--color-border);
    border-radius: var(--radius-lg); padding: 1.5rem; margin-bottom: 1.25rem;
}
.card .card-title {
    font-size: 0.75rem; font-weight: 600; margin-bottom: 1rem;
    color: var(--color-text-muted); text-transform: uppercase; letter-spacing: 0.06em;
}

/* ── Forms ─────────────────────────────────────────────────────────────── */

.form-group { margin-bottom: 0.875rem; }
label {
    display: block; margin-bottom: 0.375rem; font-weight: 500;
    color: var(--color-text-secondary); font-size: 0.8125rem;
}
input, select, textarea {
    width: 100%; padding: 0.625rem 0.875rem; font-size: 0.9375rem; font-family: inherit;
    background: var(--color-surface-light); border: 1px solid var(--color-border);
    border-radius: var(--radius-sm); color: var(--color-text);
    transition: border-color var(--transition);
}
input:focus, select:focus, textarea:focus {
    outline: none; border-color: var(--color-primary);
    box-shadow: 0 0 0 2px rgba(59,130,246,0.15);
}
input::placeholder { color: var(--color-text-muted); }
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0.875rem; }

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

.results-section { display: none; }
.results-section.visible { display: block; }

.result-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0.75rem; }
.metric {
    background: var(--color-surface-light); padding: 1rem;
    border-radius: var(--radius); text-align: center;
}
.metric-value { font-size: 1.375rem; font-weight: 700; font-family: var(--font-mono); }
.metric-label {
    font-size: 0.6875rem; color: var(--color-text-muted); text-transform: uppercase;
    letter-spacing: 0.05em; margin-top: 0.25rem;
}

.hts-info {
    background: var(--color-surface-light); padding: 0.875rem 1rem;
    border-radius: var(--radius); margin-bottom: 1rem;
    font-family: var(--font-mono); font-size: 0.85rem; color: var(--color-text-secondary);
}
.hts-code { color: var(--color-primary-light); font-weight: 600; }

.status-badge {
    display: inline-block; padding: 0.2rem 0.625rem; border-radius: 100px;
    font-weight: 600; font-size: 0.6875rem; text-transform: uppercase; letter-spacing: 0.03em;
}
.status-badge.profitable { background: rgba(16,185,129,0.12); color: var(--color-success); }
.status-badge.breakeven { background: rgba(245,158,11,0.12); color: var(--color-warning); }
.status-badge.loss { background: rgba(239,68,68,0.12); color: var(--color-danger); }

.text-success { color: var(--color-success); }
.text-warning { color: var(--color-warning); }
.text-danger { color: var(--color-danger); }

/* ── Drop Zone ─────────────────────────────────────────────────────────── */

.drop-zone {
    border: 1px dashed var(--color-border-hover); border-radius: var(--radius-lg);
    padding: 2.5rem 2rem; text-align: center; cursor: pointer;
    transition: var(--transition); background: transparent;
}
.drop-zone:hover, .drop-zone.drag-over {
    border-color: var(--color-primary); background: rgba(59,130,246,0.03);
}
.drop-zone-icon {
    width: 48px; height: 48px; margin: 0 auto 0.75rem;
    background: var(--color-surface-light); border-radius: var(--radius);
    display: flex; align-items: center; justify-content: center;
}
.drop-zone-icon svg { width: 24px; height: 24px; stroke: var(--color-text-muted); fill: none; stroke-width: 1.5; }
.drop-zone-text { color: var(--color-text-secondary); margin-bottom: 0.25rem; font-size: 0.9rem; }
.drop-zone-hint { font-size: 0.8125rem; color: var(--color-text-muted); }
.file-input { display: none; }
.file-selected {
    display: flex; align-items: center; justify-content: space-between;
    background: var(--color-surface-light); padding: 0.875rem 1rem;
    border-radius: var(--radius); margin-top: 0.875rem;
}
.file-info { display: flex; align-items: center; gap: 0.625rem; }
.file-icon {
    width: 32px; height: 32px; background: var(--color-primary-subtle);
    border-radius: var(--radius-sm); display: flex; align-items: center;
    justify-content: center; color: var(--color-primary-light); font-size: 0.75rem; font-weight: 700;
}
.file-name { font-weight: 500; font-size: 0.875rem; }
.file-size { font-size: 0.75rem; color: var(--color-text-muted); }
.file-remove {
    background: transparent; border: none; color: var(--color-text-muted);
    cursor: pointer; padding: 0.375rem; font-size: 1rem; line-height: 1;
}
.file-remove:hover { color: var(--color-danger); }

/* ── Summary Stats ─────────────────────────────────────────────────────── */

.summary-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 0.75rem; }
.stat-card {
    background: var(--color-surface-light); padding: 1rem;
    border-radius: var(--radius); text-align: center;
}
.stat-value { font-size: 1.5rem; font-weight: 700; font-family: var(--font-mono); margin-bottom: 0.125rem; }
.stat-label {
    font-size: 0.6875rem; color: var(--color-text-muted); text-transform: uppercase;
    letter-spacing: 0.05em;
}
.stat-profitable .stat-value { color: var(--color-success); }
.stat-warning .stat-value { color: var(--color-warning); }
.stat-danger .stat-value { color: var(--color-danger); }

/* ── Table ─────────────────────────────────────────────────────────────── */

.table-container {
    overflow-x: auto; border-radius: var(--radius);
    border: 1px solid var(--color-border);
}
.results-table { width: 100%; border-collapse: collapse; font-size: 0.8125rem; }
.results-table th, .results-table td {
    padding: 0.625rem 0.875rem; text-align: left;
    border-bottom: 1px solid var(--color-border);
}
.results-table th {
    background: var(--color-surface-light); font-weight: 600;
    color: var(--color-text-muted); text-transform: uppercase;
    font-size: 0.6875rem; letter-spacing: 0.04em;
    cursor: pointer; user-select: none; white-space: nowrap;
}
.results-table th:hover { color: var(--color-text-secondary); }
.results-table th .sort-icon { margin-left: 0.375rem; opacity: 0.4; }
.results-table th.sorted .sort-icon { opacity: 1; color: var(--color-primary); }
.results-table tbody tr { transition: background var(--transition); }
.results-table tbody tr:hover { background: var(--color-surface-light); }
.results-table tbody tr:last-child td { border-bottom: none; }
.results-table .mono { font-family: var(--font-mono); }
.results-table .text-right { text-align: right; }

/* ── Loading & Errors ──────────────────────────────────────────────────── */

.loading { display: none; text-align: center; padding: 2.5rem; color: var(--color-text-muted); }
.loading.visible { display: block; }
.spinner {
    width: 28px; height: 28px; border: 2px solid var(--color-border);
    border-top-color: var(--color-primary); border-radius: 50%;
    animation: spin 0.8s linear infinite; margin: 0 auto 0.75rem;
}
@keyframes spin { to { transform: rotate(360deg); } }

.error-message {
    background: rgba(239,68,68,0.1); border: 1px solid rgba(239,68,68,0.2);
    color: var(--color-danger); padding: 0.875rem 1rem; border-radius: var(--radius);
    margin-bottom: 1rem; display: none; font-size: 0.875rem;
}
.error-message.visible { display: block; }

.validation-errors {
    background: rgba(245,158,11,0.08); border: 1px solid rgba(245,158,11,0.2);
    border-radius: var(--radius); padding: 1rem; margin-bottom: 1rem;
}
.validation-errors h4 { color: var(--color-warning); margin-bottom: 0.375rem; font-size: 0.8125rem; }
.validation-errors ul { margin: 0; padding-left: 1.25rem; font-size: 0.8125rem; color: var(--color-text-secondary); }

/* ── CSV Preview ───────────────────────────────────────────────────────── */

.csv-preview {
    background: var(--color-surface-light); border-radius: var(--radius);
    padding: 0.875rem; margin: 0.875rem 0; max-height: 180px; overflow-y: auto;
}
.csv-preview table { width: 100%; font-size: 0.75rem; border-collapse: collapse; }
.csv-preview th, .csv-preview td {
    padding: 0.375rem 0.5rem; text-align: left;
    border-bottom: 1px solid var(--color-border);
}
.csv-preview th { font-weight: 600; color: var(--color-text-muted); }

/* ── Tooltips ──────────────────────────────────────────────────────────── */

.tooltip {
    position: relative;
    cursor: help;
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
}
.tooltip-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 16px;
    height: 16px;
    border-radius: 50%;
    background: var(--color-surface-light);
    color: var(--color-text-muted);
    font-size: 0.625rem;
    font-weight: 700;
    flex-shrink: 0;
    border: 1px solid var(--color-border);
    line-height: 1;
}
.tooltip::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 125%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--color-surface-dark, #1a1a2e);
    color: white;
    padding: 0.5rem 0.75rem;
    border-radius: 6px;
    font-size: 0.8rem;
    font-weight: 400;
    text-transform: none;
    letter-spacing: normal;
    white-space: normal;
    width: max-content;
    max-width: 280px;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s;
    z-index: 100;
    line-height: 1.4;
}
.tooltip:hover::after,
.tooltip:focus::after {
    opacity: 1;
}
/* Mobile: tap to show + inline fallback */
@media (max-width: 768px) {
    .tooltip::after {
        bottom: auto;
        top: 125%;
        left: 0;
        transform: none;
        max-width: 240px;
    }
}

/* ── Field Help Text ──────────────────────────────────────────────────── */

.field-help {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    margin-top: 0.25rem;
    line-height: 1.4;
}

/* ── HTS Explanation ──────────────────────────────────────────────────── */

.hts-description-text {
    display: block;
    margin-top: 0.375rem;
    font-family: var(--font-sans);
    font-size: 0.875rem;
    color: var(--color-text-secondary);
    font-weight: 400;
}

/* ── Utilities ─────────────────────────────────────────────────────────── */

.hidden { display: none !important; }

/* ── Hamburger Menu ─────────────────────────────────────────────────────── */

.nav-hamburger {
    display: none; background: none; border: 1px solid var(--color-border);
    border-radius: var(--radius-sm); padding: 0.5rem; cursor: pointer;
    color: var(--color-text); width: 44px; height: 44px;
    align-items: center; justify-content: center; flex-shrink: 0;
}
.nav-hamburger svg { width: 20px; height: 20px; stroke: currentColor; fill: none; stroke-width: 2; }

/* ── Responsive: Tablet (1024px) ───────────────────────────────────────── */

@media (max-width: 1024px) {
    .hero h1 { font-size: 2.5rem; }
    .pricing-grid { grid-template-columns: repeat(2, 1fr) !important; max-width: 720px !important; }
    .features-grid { grid-template-columns: 1fr 1fr; }
    .steps-grid { grid-template-columns: 1fr 1fr; }
    .faq-grid { grid-template-columns: 1fr 1fr; }
    .try-form-grid { grid-template-columns: 1fr 1fr; }
    .try-form-desc { grid-column: 1 / -1; }
    .cta-box { padding: 3rem 1.5rem; }
}

/* ── Responsive: Mobile (768px) ────────────────────────────────────────── */

@media (max-width: 768px) {
    /* Layout */
    .container { padding: 1rem; }
    .landing-container { padding: 0 1rem; }

    /* Nav — hamburger toggle */
    .nav-hamburger { display: inline-flex; }
    .nav-links { display: none; }
    .nav-buttons { display: none; }
    .nav-links.open, .nav-buttons.open {
        display: flex; flex-direction: column; position: absolute;
        top: 100%; left: 0; right: 0; background: var(--color-bg);
        border-bottom: 1px solid var(--color-border);
        padding: 1rem; gap: 0.75rem; z-index: 100;
    }
    .nav-links.open a { padding: 0.5rem 0; font-size: 1rem; }
    .nav-buttons.open { padding-top: 0; }
    .nav-buttons.open a { width: 100%; justify-content: center; min-height: 44px; }
    .nav { position: relative; flex-wrap: wrap; }

    /* Mobile nav combined menu */
    .nav-mobile-menu {
        display: none; flex-direction: column; width: 100%;
        background: var(--color-surface); border-top: 1px solid var(--color-border);
        padding: 1rem 0; gap: 0.25rem; order: 10;
    }
    .nav-mobile-menu.open { display: flex; }
    .nav-mobile-menu a {
        padding: 0.75rem 0.5rem; color: var(--color-text-secondary);
        font-size: 0.9375rem; border-radius: var(--radius-sm);
        min-height: 44px; display: flex; align-items: center;
    }
    .nav-mobile-menu a:hover { background: var(--color-surface-light); color: var(--color-text); text-decoration: none; }
    .nav-mobile-menu .btn { width: 100%; justify-content: center; min-height: 44px; margin-top: 0.5rem; }

    /* Hero */
    .hero { padding: 2.5rem 0 2rem; }
    .hero h1 { font-size: 2rem; }
    .hero-subtitle { font-size: 1rem; }
    .hero-buttons { flex-direction: column; align-items: center; }
    .hero-buttons .btn { width: 100%; max-width: 320px; min-height: 48px; }

    /* Sections */
    .section-header h2 { font-size: 1.5rem; }
    .section-header p { font-size: 0.9375rem; }

    /* Try It form */
    .try-form-grid { grid-template-columns: 1fr 1fr; }
    .try-form-desc { grid-column: 1 / -1; }
    .try-it-card { padding: 1.25rem; }
    .try-submit-btn { min-height: 48px; }

    /* Features, steps, etc */
    .features-grid { grid-template-columns: 1fr 1fr; gap: 1rem; }
    .steps-grid { grid-template-columns: 1fr; }
    .problem-solution { grid-template-columns: 1fr; }
    .faq-grid { grid-template-columns: 1fr; }

    /* Pricing */
    .pricing-grid { grid-template-columns: 1fr !important; max-width: 400px !important; margin: 0 auto; }
    .pricing-card .btn, .pricing-card a.btn { min-height: 48px; }

    /* CTA */
    .cta h2 { font-size: 1.5rem; }
    .cta-box { padding: 2.5rem 1.25rem; }

    /* Footer */
    .footer-links { flex-direction: column; align-items: center; gap: 0.75rem; }

    /* Forms */
    .form-row { grid-template-columns: 1fr; }
    input, select, textarea { font-size: 1rem; padding: 0.75rem 0.875rem; min-height: 44px; }
    .btn { min-height: 44px; }
    .btn-full { min-height: 48px; }

    /* Results */
    .result-grid { grid-template-columns: repeat(2, 1fr); }
    .summary-grid { grid-template-columns: repeat(2, 1fr); }
    .try-results-grid { grid-template-columns: repeat(2, 1fr); }
    .try-results-header { flex-direction: column; align-items: flex-start; }

    /* Dashboard header */
    .dashboard-header { flex-direction: column; align-items: flex-start; gap: 0.75rem; }
    .user-info { flex-wrap: wrap; gap: 0.5rem; }
    .logout-btn { min-height: 44px; padding: 0.5rem 1rem; }

    /* Dashboard tabs — horizontal scroll */
    .tabs { overflow-x: auto; -webkit-overflow-scrolling: touch; scrollbar-width: none; gap: 0; }
    .tabs::-webkit-scrollbar { display: none; }
    .tab-btn { white-space: nowrap; flex-shrink: 0; padding: 0.75rem 1rem; min-height: 44px; font-size: 0.8125rem; }

    /* Tables — horizontal scroll */
    .table-container { overflow-x: auto; -webkit-overflow-scrolling: touch; }
    .results-table { min-width: 600px; }
    .results-table th, .results-table td { padding: 0.5rem 0.625rem; font-size: 0.75rem; }

    /* Drop zone */
    .drop-zone { padding: 2rem 1rem; }

    /* Cards */
    .card { padding: 1.25rem; }

    /* Blog article tables */
    .blog-content table { display: block; overflow-x: auto; -webkit-overflow-scrolling: touch; }
    .blog-content img { max-width: 100%; height: auto; }
    .blog-content pre { overflow-x: auto; -webkit-overflow-scrolling: touch; }
}

/* ── Responsive: Small Mobile (480px) ──────────────────────────────────── */

@media (max-width: 480px) {
    .container { padding: 0.75rem; }
    .landing-container { padding: 0 0.75rem; }

    /* Hero */
    .hero { padding: 2rem 0 1.5rem; }
    .hero h1 { font-size: 1.625rem; line-height: 1.15; }
    .hero-subtitle { font-size: 0.9375rem; }
    .hero-badge { font-size: 0.75rem; padding: 0.3rem 0.75rem; }

    /* Forms — single column */
    .try-form-grid { grid-template-columns: 1fr; }
    .try-it-card { padding: 1rem; }

    /* Grids — single column */
    .features-grid { grid-template-columns: 1fr; }
    .result-grid { grid-template-columns: 1fr; }
    .try-results-grid { grid-template-columns: repeat(2, 1fr); }
    .summary-grid { grid-template-columns: 1fr 1fr; }

    /* Pricing */
    .pricing-card { padding: 1.5rem; }

    /* Section headers */
    .section-header h2 { font-size: 1.375rem; }
    .section-header p { font-size: 0.875rem; }
    .cta h2 { font-size: 1.375rem; }
    .cta-box { padding: 2rem 1rem; }
    .cta p { font-size: 0.9375rem; }

    /* Cards */
    .card { padding: 1rem; margin-bottom: 1rem; }
    .step-card { padding: 1.25rem; }
    .feature-card { padding: 1.25rem; }
    .faq-item { padding: 1rem; }
    .problem-card, .solution-card { padding: 1.5rem; }

    /* Dashboard */
    .tab-btn { padding: 0.625rem 0.75rem; font-size: 0.75rem; }
    .metric-value { font-size: 1.125rem; }
    .stat-value { font-size: 1.25rem; }
    .hts-info { font-size: 0.75rem; padding: 0.75rem; word-break: break-all; }

    /* Touch targets */
    .btn { padding: 0.75rem 1rem; font-size: 0.9375rem; }
    .btn-large { padding: 0.875rem 1.25rem; }
    .btn-group { flex-direction: column; }
    .btn-group .btn { width: 100%; justify-content: center; }
    .file-remove { width: 44px; height: 44px; display: flex; align-items: center; justify-content: center; }

    /* Blog */
    .blog-content h1 { font-size: 1.5rem; }
    .blog-content h2 { font-size: 1.25rem; }
    .blog-content p { font-size: 0.9375rem; }
}

/* ── Responsive: Very Small Mobile (320px) ─────────────────────────────── */

@media (max-width: 320px) {
    .container { padding: 0.5rem; }
    .landing-container { padding: 0 0.5rem; }

    .hero h1 { font-size: 1.375rem; }
    .hero-subtitle { font-size: 0.875rem; }
    .hero-badge { font-size: 0.6875rem; }

    .section-header h2 { font-size: 1.25rem; }
    .cta h2 { font-size: 1.25rem; }

    .pricing-amount { font-size: 2rem; }
    .pricing-card { padding: 1.25rem; }

    .nav-logo { font-size: 1rem; }
    .try-results-grid { grid-template-columns: 1fr; }
    .summary-grid { grid-template-columns: 1fr; }
    .result-grid { grid-template-columns: 1fr; }

    .try-metric-value { font-size: 1rem; }
    .metric-value { font-size: 1rem; }
    .stat-value { font-size: 1.125rem; }

    .card { padding: 0.75rem; }
    .try-it-card { padding: 0.75rem; }
    .cta-box { padding: 1.5rem 0.75rem; }

    .results-table { min-width: 500px; }
    .results-table th, .results-table td { padding: 0.375rem 0.5rem; font-size: 0.6875rem; }
}

/* ── HTS Category Combobox ──────────────────────────────────────────────── */

.hts-combobox {
    position: relative;
    width: 100%;
}

.hts-combobox-input-wrap {
    position: relative;
    display: flex;
    align-items: center;
}

.hts-combobox-input-wrap input {
    padding-right: 2.25rem;
}

.hts-combobox-input-wrap input.has-selection {
    border-color: var(--color-primary);
    background: rgba(59,130,246,0.04);
}

.hts-combobox-clear {
    position: absolute;
    right: 0.5rem;
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    font-size: 1rem;
    line-height: 1;
    padding: 0.25rem 0.375rem;
    border-radius: 4px;
    transition: color var(--transition);
    width: auto;
}
.hts-combobox-clear:hover { color: var(--color-danger); background: rgba(239,68,68,0.08); }

.hts-dropdown {
    position: absolute;
    top: calc(100% + 4px);
    left: 0;
    right: 0;
    background: var(--color-surface);
    border: 1px solid var(--color-border-hover);
    border-radius: var(--radius);
    box-shadow: var(--shadow-lg);
    z-index: 1000;
    max-height: 320px;
    overflow-y: auto;
    scrollbar-width: thin;
}

.hts-dropdown::-webkit-scrollbar { width: 6px; }
.hts-dropdown::-webkit-scrollbar-track { background: transparent; }
.hts-dropdown::-webkit-scrollbar-thumb { background: var(--color-border-hover); border-radius: 3px; }

.hts-dropdown-empty {
    padding: 1rem;
    text-align: center;
    color: var(--color-text-muted);
    font-size: 0.8125rem;
}

.hts-dropdown-header {
    padding: 0.5rem 0.875rem 0.375rem;
    font-size: 0.6875rem;
    font-weight: 600;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--color-border);
}

.hts-option {
    display: flex;
    align-items: baseline;
    gap: 0.625rem;
    padding: 0.625rem 0.875rem;
    cursor: pointer;
    transition: background var(--transition);
    border-bottom: 1px solid var(--color-border);
}
.hts-option:last-child { border-bottom: none; }
.hts-option:hover, .hts-option.active {
    background: var(--color-primary-subtle);
}

.hts-option-code {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--color-primary-light);
    white-space: nowrap;
    min-width: 60px;
    flex-shrink: 0;
}

.hts-option-desc {
    font-size: 0.875rem;
    color: var(--color-text);
    line-height: 1.4;
}

.hts-option-keywords {
    font-size: 0.7rem;
    color: var(--color-text-muted);
    margin-top: 0.1rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 280px;
}

.hts-selected-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    background: var(--color-primary-subtle);
    border: 1px solid rgba(59,130,246,0.3);
    border-radius: 4px;
    padding: 0.1875rem 0.5rem;
    font-size: 0.75rem;
    color: var(--color-primary-light);
    font-family: var(--font-mono);
    margin-top: 0.375rem;
}

/* highlight matched text in dropdown */
.hts-option mark {
    background: rgba(59,130,246,0.2);
    color: var(--color-primary-light);
    border-radius: 2px;
    padding: 0 1px;
}