:root {
    --bg: #f8fafc;
    --surface: #ffffff;
    --surface-soft: #f1f5f9;
    --text: #0f172a;
    --muted: #475569;
    --border: #e2e8f0;
    --primary: #0f172a;
    --accent: #2563eb;
    --accent-soft: #dbeafe;
    --success: #166534;
    --success-bg: #dcfce7;
    --radius: 18px;
    --shadow: 0 12px 28px rgba(15, 23, 42, 0.08);
    --container: 1200px;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
    margin: 0;
    font-family: Arial, Helvetica, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.65;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { display: block; max-width: 100%; }
.container { width: min(100% - 32px, var(--container)); margin: 0 auto; }
.skip-link {
    position: absolute; left: -9999px; top: auto; width: 1px; height: 1px; overflow: hidden;
}
.skip-link:focus {
    left: 16px; top: 16px; width: auto; height: auto; overflow: visible; z-index: 1001;
    background: var(--primary); color: #fff; padding: 10px 14px; border-radius: 10px;
}
.site-header {
    position: sticky; top: 0; z-index: 999;
    background: rgba(255,255,255,0.96); backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
}
.header-inner {
    min-height: 66px; display: flex; align-items: center; justify-content: space-between; gap: 18px;
}
.logo {
    display: inline-flex; align-items: center; gap: 12px; color: var(--text); font-weight: 800; text-decoration: none;
}
.logo-badge {
    width: 36px; height: 36px; border-radius: 12px; display: inline-flex; align-items: center; justify-content: center;
    color: #fff; background: linear-gradient(135deg, #2563eb, #0f172a); font-size: 1.1rem;
}
.logo-text-wrap { display: inline-flex; flex-direction: column; line-height: 1.1; font-size: 0.98rem; }
.main-nav ul {
    list-style: none; margin: 0; padding: 0; display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
}
.main-nav a {
    color: var(--text); text-decoration: none; font-weight: 700; padding: 8px 12px; border-radius: 999px;
    transition: background 0.15s ease, color 0.15s ease;
}
.main-nav a:hover, .main-nav a:focus, .main-nav a.current { background: var(--accent-soft); color: #1d4ed8; outline: none; }
.hero { padding: 28px 0 14px; }
.hero-card {
    background: linear-gradient(135deg, #ffffff, #eff6ff); border: 1px solid var(--border); box-shadow: var(--shadow); border-radius: 24px; padding: 24px 28px;
}
.hero-card.compact { padding-bottom: 20px; }
.eyebrow {
    display: inline-block; background: var(--accent-soft); color: #1d4ed8; border-radius: 999px;
    padding: 6px 12px; font-size: 0.85rem; font-weight: 700; margin-bottom: 12px;
}
h1, h2, h3 { margin-top: 0; line-height: 1.2; }
h1 { font-size: clamp(1.9rem, 4vw, 2.8rem); margin-bottom: 10px; }
h2 { font-size: 1.65rem; margin-bottom: 10px; }
h3 { font-size: 1.15rem; margin-bottom: 8px; }
.lead-text, .muted, .hero p { color: var(--muted); }
.hero p { max-width: 760px; margin: 0; font-size: 1.02rem; }
.hero-points { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 16px; }
.hero-points span { background: #fff; border: 1px solid var(--border); border-radius: 999px; padding: 8px 12px; color: var(--muted); }
.breadcrumbs { margin-top: 16px; }
.breadcrumbs ol { margin: 0; padding: 0; list-style: none; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; color: var(--muted); }
.breadcrumbs li:not(:last-child)::after { content: '/'; margin-left: 8px; color: #94a3b8; }
.page-section { padding: 8px 0 36px; }
.content-grid { display: grid; grid-template-columns: minmax(0, 2fr) minmax(260px, 340px); gap: 24px; }
.stack, .stack-inner { display: grid; gap: 18px; }
.card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 22px; }
.link-list, .footer-links, .feature-list, .hub-list { list-style: none; margin: 0; padding: 0; }
.link-list { display: grid; gap: 10px; }
.link-list a, .hub-list a {
    display: block; padding: 12px 14px; border-radius: 12px; background: var(--surface-soft); border: 1px solid var(--border); color: var(--text); font-weight: 700; text-decoration: none;
}
.link-list a:hover, .hub-list a:hover { background: #e8eef6; color: var(--accent); }
.calc-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px; align-items: end; }
.field { display: grid; gap: 8px; }
.field label { font-weight: 700; font-size: 0.95rem; }
.field input {
    width: 100%; min-height: 48px; border: 1px solid #cbd5e1; border-radius: 12px; padding: 0 14px; font-size: 1rem; background: #fff; color: var(--text);
}
.field input:focus { outline: 2px solid #93c5fd; outline-offset: 1px; border-color: #60a5fa; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 18px; }
.btn { appearance: none; border: none; min-height: 46px; padding: 0 18px; border-radius: 12px; font-size: 0.98rem; font-weight: 700; cursor: pointer; transition: transform 0.15s ease; }
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--primary); color: #fff; }
.btn-secondary { background: var(--surface-soft); color: var(--text); border: 1px solid var(--border); }
.error { margin-top: 12px; display: none; border-radius: 12px; padding: 12px 14px; background: #fef2f2; color: #b91c1c; font-weight: 700; }
.error.show { display: block; }
.result { margin-top: 16px; display: none; border: 1px solid #bbf7d0; background: var(--success-bg); border-radius: 14px; padding: 18px; }
.result.show { display: block; }
.result strong { display: block; font-size: 1.2rem; color: var(--success); margin-bottom: 6px; }
.formula { margin-top: 10px; color: #166534; }
.examples { display: grid; gap: 14px; }
.example-item { background: var(--surface-soft); border: 1px solid var(--border); border-radius: 14px; padding: 16px; }
.note-box { background: linear-gradient(180deg, #ffffff, #f8fafc); border: 1px solid var(--border); border-radius: 14px; padding: 16px; color: var(--muted); }
.faq details { border: 1px solid var(--border); border-radius: 14px; background: #fff; padding: 16px; }
.faq details + details { margin-top: 12px; }
.faq summary { font-weight: 700; cursor: pointer; list-style: none; }
.faq summary::-webkit-details-marker { display: none; }
.faq p { margin: 12px 0 0; color: var(--muted); }
.info-grid { display: grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap: 16px; }
.info-card, .page-card { background: #fff; border: 1px solid var(--border); border-radius: 18px; padding: 20px; box-shadow: var(--shadow); }
.info-card p, .page-card p { color: var(--muted); margin-bottom: 0; }
.page-cards { display: grid; grid-template-columns: repeat(2, minmax(0,1fr)); gap: 16px; }
.page-card h3 { margin-bottom: 8px; }
.page-card p { margin-top: 0; }
.page-card a.card-link { display: inline-flex; align-items: center; margin-top: 8px; font-weight: 700; }
.hub-list { display: grid; gap: 14px; }
.hub-list li article { background: var(--surface); border: 1px solid var(--border); border-radius: 18px; padding: 18px; box-shadow: var(--shadow); }
.hub-list p { color: var(--muted); margin: 8px 0 0; }
.site-footer { margin-top: 40px; background: #fff; border-top: 1px solid var(--border); }
.footer-inner { padding: 24px 0; display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; color: var(--muted); }
.footer-links { display: flex; flex-wrap: wrap; gap: 14px; }
.footer-links a { color: var(--muted); }
.footer-links a:hover { color: var(--accent); }
.section-divider { border-top: 1px solid var(--border); margin-top: 8px; padding-top: 18px; }
@media (max-width: 980px) {
    .content-grid, .info-grid, .page-cards { grid-template-columns: 1fr; }
    .header-inner { flex-direction: column; align-items: flex-start; padding: 12px 0; }
}
@media (max-width: 720px) {
    .hero-card, .card, .page-card, .info-card { padding: 18px; }
    .calc-grid { grid-template-columns: 1fr; }
    .main-nav ul { gap: 6px; }
    .main-nav a { padding: 8px 10px; font-size: 0.95rem; }
}