:root {
  --ink: #172033;
  --muted: #667085;
  --line: #d8dee9;
  --blue: #2457a6;
  --blue-soft: #edf4ff;
  --red: #c82f45;
  --red-soft: #fff1f3;
  --green: #217a4b;
  --green-soft: #edf9f2;
  --surface: #ffffff;
  --background: #f5f7fb;
  --shadow: 0 12px 32px rgba(29, 48, 78, 0.08);
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--background);
  color: var(--ink);
  font-family: Arial, "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  line-height: 1.55;
}
.shell { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }
.site-header { background: rgba(255,255,255,.96); border-bottom: 1px solid var(--line); }
.header-inner { min-height: 76px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { color: inherit; text-decoration: none; display: flex; align-items: center; gap: 12px; }
.brand-mark { width: 42px; height: 42px; display: grid; place-items: center; border-radius: 11px; background: var(--blue); color: white; font-weight: 700; font-size: 22px; }
.brand strong { display: block; letter-spacing: .04em; }
.brand small { display: block; color: var(--muted); font-size: 12px; }
nav { display: flex; align-items: center; gap: 24px; }
nav a { color: #344054; text-decoration: none; font-size: 14px; }
.language-link { padding: 8px 13px; border: 1px solid var(--line); border-radius: 8px; background: white; }
.hero { padding: 56px 0 28px; display: flex; align-items: end; justify-content: space-between; gap: 28px; }
.hero h1, .page-heading h1 { margin: 8px 0 6px; font-size: clamp(28px, 4vw, 42px); line-height: 1.2; }
.hero p, .page-heading p { margin: 0; color: var(--muted); }
.eyebrow { color: var(--blue); font-weight: 700; letter-spacing: .12em; text-transform: uppercase; font-size: 13px; }
.research-badge { background: var(--blue-soft); color: var(--blue); border: 1px solid #cfe0fa; padding: 9px 14px; border-radius: 999px; font-size: 13px; font-weight: 700; }
.calculator-grid { display: grid; grid-template-columns: .9fr 1.1fr; gap: 24px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: 16px; padding: 28px; box-shadow: var(--shadow); }
.card-heading { display: flex; gap: 14px; align-items: flex-start; margin-bottom: 24px; }
.card-heading h2 { margin: 0 0 4px; font-size: 21px; }
.card-heading p { margin: 0; color: var(--muted); font-size: 13px; }
.step-number { flex: 0 0 auto; display: grid; place-items: center; width: 30px; height: 30px; color: white; background: var(--blue); border-radius: 50%; font-weight: 700; }
.field-group { margin: 0 0 18px; }
.field-group label { display: block; font-weight: 700; margin-bottom: 7px; }
.numeric-input { width: 100%; border: 1px solid #bbc5d4; border-radius: 9px; padding: 12px 13px; font: inherit; background: white; }
.numeric-input:focus { outline: 3px solid rgba(36,87,166,.15); border-color: var(--blue); }
.demo-note { color: var(--muted); font-size: 12px; }
button { width: 100%; border: 0; border-radius: 9px; padding: 13px; background: var(--blue); color: white; font: inherit; font-weight: 700; cursor: pointer; }
button:hover { background: #194989; }
.result-card { min-height: 470px; }
.result-placeholder { min-height: 300px; display: grid; place-items: center; align-content: center; text-align: center; color: var(--muted); }
.placeholder-ring { width: 90px; height: 90px; border-radius: 50%; border: 10px solid #e8edf4; border-top-color: #aab9cf; margin-bottom: 22px; }
.probability-block { background: var(--blue-soft); border-radius: 14px; padding: 24px; margin-bottom: 18px; }
.probability-block span, .probability-block small { display: block; color: var(--muted); }
.probability-block strong { display: block; font-size: 54px; line-height: 1.1; margin: 7px 0; color: var(--blue); font-variant-numeric: tabular-nums; }
.result-metrics { display: grid; grid-template-columns: 1fr auto; gap: 16px; align-items: center; margin-bottom: 18px; }
.result-metrics span { display: block; color: var(--muted); font-size: 13px; }
.result-metrics strong { font-size: 24px; }
.risk-pill { border-radius: 999px; padding: 11px 18px; font-weight: 700; }
.risk-pill.high { background: var(--red-soft); color: var(--red); border: 1px solid #fac8d1; }
.risk-pill.low { background: var(--green-soft); color: var(--green); border: 1px solid #bde7cd; }
.interpretation { border-top: 1px solid var(--line); padding-top: 17px; color: #475467; }
.notice { border-radius: 10px; padding: 13px 15px; margin: 12px 0; }
.notice p { margin: 4px 0 0; }
.notice.error, .field-error { color: #9b1c31; background: var(--red-soft); }
.notice.warning { background: #fff8e7; color: #805b16; }
.field-error { font-size: 12px; padding: 5px 8px; border-radius: 5px; }
.boundary-strip { margin: 24px 0 44px; border-left: 4px solid var(--blue); background: white; padding: 16px 20px; display: flex; gap: 18px; box-shadow: var(--shadow); }
.boundary-strip span { color: var(--muted); }
.page-heading { padding: 52px 0 25px; }
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; margin-bottom: 50px; }
.about-grid .model-card { grid-column: 1 / -1; }
.about-grid h2 { margin-top: 0; }
dl { margin: 0; }
dl div { display: grid; grid-template-columns: 180px 1fr; gap: 20px; padding: 10px 0; border-bottom: 1px solid #edf0f5; }
dt { color: var(--muted); } dd { margin: 0; font-weight: 600; }
.site-footer { background: #172033; color: #d6deea; padding: 28px 0; font-size: 12px; }
.site-footer p { margin: 5px 0; }
@media (max-width: 780px) {
  .header-inner, .hero { align-items: flex-start; flex-direction: column; padding: 16px 0; }
  nav { width: 100%; gap: 15px; flex-wrap: wrap; }
  .calculator-grid, .about-grid { grid-template-columns: 1fr; }
  .about-grid .model-card { grid-column: auto; }
  .boundary-strip { flex-direction: column; gap: 6px; }
  .result-card { min-height: auto; }
  dl div { grid-template-columns: 1fr; gap: 3px; }
}