:root {
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --primary: #4f46e5;
    --primary-dark: #4338ca;
    --primary-light: #818cf8;
    --gradient: linear-gradient(135deg, #4f46e5 0%, #7c3aed 100%);
    --gradient-subtle: linear-gradient(135deg, #eef2ff 0%, #faf5ff 100%);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --glass-bg: rgba(255, 255, 255, 0.65);
    --glass-border: rgba(255, 255, 255, 0.35);
    --glass-shadow: 0 8px 40px rgba(79, 70, 229, 0.08);
    --glass-shadow-hover: 0 12px 48px rgba(79, 70, 229, 0.15);
    --radius: 16px;
    --radius-sm: 10px;
    --radius-full: 9999px;
    --transition: 0.35s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    --max-width: 1280px;
    --error: #dc2626;
    --error-bg: #fef2f2;
    --success: #16a34a;
}

html {
    scroll-behavior: smooth;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: var(--font);
    color: var(--text-primary);
    background:
        radial-gradient(circle at 15% 0%, #eef2ff 0%, transparent 45%),
        radial-gradient(circle at 90% 20%, #faf5ff 0%, transparent 40%),
        #fbfcff;
    -webkit-font-smoothing: antialiased;
}

.wrap {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* ---------- Skip link ---------- */
.skip-link {
    position: absolute;
    top: -48px;
    left: 16px;
    background: var(--text-primary);
    color: #fff;
    padding: 10px 18px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.9rem;
    text-decoration: none;
    z-index: 100;
    transition: top var(--transition);
}
.skip-link:focus {
    top: 12px;
}

/* ---------- Header ---------- */
.site-header {
    position: sticky;
    top: 0;
    z-index: 50;
    background: rgba(251, 252, 255, 0.75);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(79, 70, 229, 0.08);
    padding: 14px 0;
}
.header-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}
.brand {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--text-primary);
    text-decoration: none;
    flex-shrink: 0;
}
.brand-mark { flex-shrink: 0; }

.site-nav {
    display: flex;
    align-items: center;
    gap: 28px;
    margin: 0 auto;
}
.site-nav a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: 0.92rem;
    padding: 6px 2px;
    position: relative;
    transition: color var(--transition);
}
.site-nav a::after {
    content: '';
    position: absolute;
    left: 0; right: 0; bottom: -2px;
    height: 2px;
    background: var(--gradient);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform var(--transition);
}
.site-nav a:hover { color: var(--text-primary); }
.site-nav a:hover::after { transform: scaleX(1); }

.header-badge {
    flex-shrink: 0;
    background: var(--gradient-subtle);
    color: var(--primary-dark);
    font-size: 0.78rem;
    font-weight: 700;
    padding: 6px 14px;
    border-radius: var(--radius-full);
    border: 1px solid rgba(79, 70, 229, 0.12);
    white-space: nowrap;
}

@media (max-width: 720px) {
    .site-nav { display: none; }
    .header-badge { display: none; }
    .header-inner { justify-content: center; }
}

/* Offset anchored sections so the sticky header doesn't cover them */
#calculator, #how-it-works, #faq {
    scroll-margin-top: 84px;
}

/* ---------- Hero ---------- */
.hero { padding: 24px 24px 8px; text-align: center; }
.hero h1 {
    font-size: clamp(2rem, 4vw, 2.75rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 0 0 10px;
}
.hero-sub {
    color: var(--text-secondary);
    font-size: 1.05rem;
    margin: 0 auto;
    max-width: 520px;
}

/* ---------- Calculator layout ---------- */
.calc-wrap {
    display: grid;
    grid-template-columns: 1.15fr 1fr;
    gap: 28px;
    align-items: start;
    padding-top: 32px;
    padding-bottom: 56px;
}
@media (max-width: 900px) {
    .calc-wrap { grid-template-columns: 1fr; }
}

.calc-card, .results-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    box-shadow: var(--glass-shadow);
    border-radius: var(--radius);
    padding: 28px;
    backdrop-filter: blur(16px);
}
.results-card { position: sticky; top: 24px; }
@media (max-width: 900px) { .results-card { position: static; } }

/* ---------- Fields ---------- */
.field-group { margin-bottom: 22px; }
.group-heading h2 { font-size: 1.05rem; margin: 0 0 4px; }
.group-help { color: var(--text-muted); font-size: 0.85rem; margin: 0 0 12px; }

label {
    display: block;
    font-weight: 600;
    font-size: 0.9rem;
    margin-bottom: 6px;
}
.optional-tag { color: var(--text-muted); font-weight: 400; }

input, select {
    font-family: var(--font);
    font-size: 1rem;
    color: var(--text-primary);
    background: #fff;
    border: 1.5px solid #e2e8f0;
    border-radius: var(--radius-sm);
    padding: 12px 14px;
    width: 100%;
    transition: border-color var(--transition), box-shadow var(--transition);
}
input:focus, select:focus, button:focus-visible {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.15);
}

.input-row { display: flex; gap: 8px; }
.input-row input { flex: 1 1 auto; min-width: 0; }
.input-row select { flex: 0 0 auto; width: auto; min-width: 110px; }
.unit-suffix {
    display: flex; align-items: center; padding: 0 10px;
    color: var(--text-secondary); font-weight: 600;
}

.two-col { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 480px) { .two-col { grid-template-columns: 1fr; } }

.unit-field { margin-bottom: 14px; }
.helper-text { font-size: 0.82rem; color: var(--text-muted); margin: 6px 0 0; }
.field-error {
    font-size: 0.82rem;
    color: var(--error);
    margin: 6px 0 0;
    display: none;
}
.field-error.visible { display: block; }
input.invalid, select.invalid { border-color: var(--error); background: var(--error-bg); }

/* ---------- Eave rows ---------- */
.eave-rows { display: flex; flex-direction: column; gap: 10px; }
.eave-row { display: grid; grid-template-columns: 1fr 110px 100px 40px; gap: 8px; align-items: center; }
@media (max-width: 560px) { .eave-row { grid-template-columns: 1fr 1fr; grid-template-areas: "label label" "len unit" "remove remove"; } }
.eave-row .row-label { font-weight: 500; }
.running-total { margin-top: 12px; font-size: 0.95rem; }
.running-total strong { color: var(--primary); }

.btn-icon-remove {
    background: none; border: none; cursor: pointer; color: var(--text-muted);
    font-size: 1.1rem; padding: 8px; border-radius: var(--radius-sm);
    transition: color var(--transition), background var(--transition);
}
.btn-icon-remove:hover { color: var(--error); background: var(--error-bg); }
.btn-icon-remove:disabled { opacity: 0.3; cursor: not-allowed; }

/* ---------- Collapsibles ---------- */
.collapsible {
    border: 1px solid #e2e8f0;
    border-radius: var(--radius-sm);
    margin-bottom: 14px;
    overflow: hidden;
}
.collapsible summary {
    cursor: pointer;
    padding: 14px 16px;
    font-weight: 600;
    font-size: 0.95rem;
    list-style: none;
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.collapsible summary::-webkit-details-marker { display: none; }
.collapsible summary::after {
    content: '+';
    font-size: 1.2rem;
    color: var(--primary);
    transition: transform var(--transition);
}
.collapsible[open] summary::after { transform: rotate(45deg); }
.collapsible-body { padding: 0 16px 16px; }

/* ---------- Buttons ---------- */
.btn-primary {
    width: 100%;
    background: var(--gradient);
    color: #fff;
    border: none;
    font-family: var(--font);
    font-weight: 700;
    font-size: 1rem;
    padding: 15px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: transform var(--transition), box-shadow var(--transition);
    box-shadow: 0 6px 20px rgba(79, 70, 229, 0.25);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 10px 28px rgba(79, 70, 229, 0.32); }

.btn-secondary {
    width: 100%;
    background: transparent;
    color: var(--text-secondary);
    border: 1.5px solid #e2e8f0;
    font-family: var(--font);
    font-weight: 600;
    font-size: 0.95rem;
    padding: 13px;
    border-radius: var(--radius-sm);
    margin-top: 10px;
    cursor: pointer;
    transition: border-color var(--transition), color var(--transition);
}
.btn-secondary:hover { border-color: var(--primary); color: var(--primary); }

.btn-ghost {
    background: none;
    border: 1.5px dashed var(--primary-light);
    color: var(--primary);
    font-family: var(--font);
    font-weight: 600;
    font-size: 0.9rem;
    padding: 10px 14px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background var(--transition);
}
.btn-ghost:hover { background: var(--gradient-subtle); }
.btn-ghost.small { padding: 8px 12px; font-size: 0.82rem; border-style: solid; }

/* ---------- Results card ---------- */
.results-empty { color: var(--text-muted); text-align: center; padding: 40px 10px; }
.results-content { animation: fadeSlideIn 0.4s ease; }
@keyframes fadeSlideIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

.unit-toggle { display: inline-flex; background: #fff; border-radius: var(--radius-full); padding: 4px; margin-bottom: 18px; border: 1px solid #e2e8f0; }
.unit-toggle-btn {
    border: none; background: none; padding: 6px 16px; border-radius: var(--radius-full);
    font-family: var(--font); font-weight: 600; font-size: 0.82rem; cursor: pointer; color: var(--text-secondary);
    transition: background var(--transition), color var(--transition);
}
.unit-toggle-btn.active { background: var(--gradient); color: #fff; }

.result-label { color: var(--text-secondary); font-size: 0.9rem; margin: 0 0 4px; }
.result-main {
    font-size: 2.6rem; font-weight: 800; margin: 0 0 20px;
    background: var(--gradient); -webkit-background-clip: text; background-clip: text; color: transparent;
}

.result-table {
    background: var(--gradient-subtle);
    border-radius: var(--radius-sm);
    padding: 6px 16px;
    margin: 0 0 20px;
}
.result-row { display: flex; justify-content: space-between; padding: 10px 0; border-bottom: 1px solid rgba(79, 70, 229, 0.08); font-size: 0.92rem; }
.result-row:last-child { border-bottom: none; }
.result-row dt { color: var(--text-secondary); margin: 0; font-weight: 500; }
.result-row dd { margin: 0; font-weight: 700; }

.result-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.copy-toast { color: var(--success); font-size: 0.82rem; font-weight: 600; margin: 10px 0 0; }

/* ---------- Info / FAQ ---------- */
.info-section, .faq-section { padding: 40px 24px; max-width: 760px; }
.info-section h2, .faq-section h2 { font-size: 1.5rem; margin-bottom: 14px; }
.info-section p, .faq-item p { color: var(--text-secondary); line-height: 1.7; }
.example {
    background: var(--gradient-subtle);
    padding: 14px 18px;
    border-radius: var(--radius-sm);
    color: var(--text-primary) !important;
    font-weight: 600;
    display: inline-block;
}
.faq-item { margin-bottom: 22px; }
.faq-item h3 { font-size: 1.05rem; margin: 0 0 6px; }

/* ---------- Footer ---------- */
.site-footer {
    border-top: 1px solid #e2e8f0;
    margin-top: 20px;
    background: var(--gradient-subtle);
}
.footer-grid {
    display: grid;
    grid-template-columns: 1.6fr 1fr 1fr;
    gap: 32px;
    padding: 44px 24px 32px;
}
@media (max-width: 720px) {
    .footer-grid { grid-template-columns: 1fr; gap: 28px; text-align: center; }
    .footer-brand .brand { justify-content: center; }
}
.footer-brand .brand {
    font-size: 1.05rem;
    margin-bottom: 10px;
}
.footer-blurb {
    color: var(--text-secondary);
    font-size: 0.88rem;
    line-height: 1.6;
    max-width: 320px;
    margin: 0;
}
@media (max-width: 720px) { .footer-blurb { max-width: none; margin: 0 auto; } }

.footer-col h3 {
    font-size: 0.8rem;
    text-transform: none;
    color: var(--text-muted);
    font-weight: 700;
    margin: 0 0 12px;
}
.footer-col a {
    display: block;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    padding: 5px 0;
    transition: color var(--transition);
}
.footer-col a:hover { color: var(--primary); }

.footer-bottom {
    border-top: 1px solid rgba(79, 70, 229, 0.1);
    padding: 20px 24px 28px;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.82rem;
}
.disclaimer { max-width: 560px; margin: 20px auto 0; }

/* ---------- Legal pages ---------- */
.legal-page { padding: 48px 24px 60px; max-width: 720px; }
.legal-page h1 { font-size: 2rem; margin-bottom: 6px; }
.legal-updated { color: var(--text-muted); font-size: 0.85rem; margin-bottom: 28px; }
.legal-page h2 { font-size: 1.15rem; margin: 28px 0 8px; }
.legal-page p { color: var(--text-secondary); line-height: 1.7; }
.legal-page a { color: var(--primary); }
.legal-note {
    margin-top: 32px;
    padding: 14px 16px;
    background: var(--gradient-subtle);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    color: var(--text-secondary) !important;
}
.contact-email { font-size: 1.2rem; font-weight: 700; margin: 20px 0; }

/* ---------- Print ---------- */
@media print {
    .site-header, .calc-card, .info-section, .faq-section, .site-footer, .result-actions, .unit-toggle { display: none !important; }
    .results-card { box-shadow: none; border: none; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
    * { animation: none !important; transition: none !important; }
}