:root {
  --bg: #f7f8fb;
  --surface: #ffffff;
  --ink: #1a2233;
  --muted: #5b6577;
  --brand: #2f6df6;
  --brand-dark: #1f4fc0;
  --border: #e6e9f0;
  --radius: 14px;
  --shadow: 0 6px 24px rgba(26, 34, 51, 0.06);
  --maxw: 860px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial,
    "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.65;
  font-size: 17px;
}

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

.wrap { max-width: var(--maxw); margin: 0 auto; padding: 0 20px; }

header.site {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
header.site .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}
.brand {
  font-weight: 700;
  font-size: 20px;
  letter-spacing: -0.02em;
  color: var(--ink);
}
.brand span { color: var(--brand); }
header nav a { color: var(--muted); margin-left: 22px; font-size: 15px; }

main { padding: 48px 0 64px; }

.hero h1 {
  font-size: 38px;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 12px;
}
.hero p.lead {
  font-size: 19px;
  color: var(--muted);
  margin: 0 0 8px;
  max-width: 640px;
}

.section-title {
  margin: 44px 0 16px;
  font-size: 24px;
  letter-spacing: -0.01em;
}

.tool-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px 26px;
  margin-bottom: 22px;
}
.tool-card h3 {
  margin: 0 0 4px;
  font-size: 22px;
}
.tool-card .tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  color: var(--brand);
  background: #eaf1ff;
  padding: 3px 10px;
  border-radius: 999px;
  margin-bottom: 12px;
}
.tool-card p { color: var(--muted); margin: 0 0 16px; }
.btn {
  display: inline-block;
  background: var(--brand);
  color: #fff;
  font-weight: 600;
  padding: 11px 20px;
  border-radius: 10px;
  font-size: 15px;
}
.btn:hover { background: var(--brand-dark); text-decoration: none; }

.explain { margin-top: 8px; color: var(--muted); font-size: 16px; }
.explain h2 { color: var(--ink); font-size: 20px; margin: 28px 0 8px; }
.explain p { margin: 0 0 14px; }

footer.site {
  border-top: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  font-size: 14px;
}
footer.site .wrap {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px;
  padding: 24px 20px;
}

/* Tool page specifics */
.calc {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 26px;
  margin-bottom: 28px;
}
.field { margin-bottom: 18px; }
.field label {
  display: block;
  font-weight: 600;
  margin-bottom: 6px;
  font-size: 15px;
}
.field .hint { font-weight: 400; color: var(--muted); font-size: 13px; }
.field input {
  width: 100%;
  padding: 12px 14px;
  font-size: 16px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fbfcfe;
  color: var(--ink);
}
.field input:focus {
  outline: none;
  border-color: var(--brand);
  box-shadow: 0 0 0 3px #eaf1ff;
}
.result {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  margin-top: 8px;
}
.result.four { grid-template-columns: repeat(4, 1fr); }
.warn {
  background: #fff5f2;
  border: 1px solid #ffd4c2;
  color: #9a3412;
  border-radius: 10px;
  padding: 12px 16px;
  margin-top: 14px;
  font-size: 15px;
}
.result .box {
  background: #f3f6fd;
  border-radius: 12px;
  padding: 16px;
  text-align: center;
}
.result .box .k { font-size: 13px; color: var(--muted); }
.result .box .v { font-size: 22px; font-weight: 700; color: var(--ink); margin-top: 4px; }
.note { font-size: 13px; color: var(--muted); margin-top: 14px; }

/* EEAT content sections */
.updated { font-size: 14px; color: var(--muted); margin: 0 0 14px; }
.explain li { margin-bottom: 12px; }
.explain li strong { color: var(--ink); }
.explain h3 { color: var(--ink); font-size: 17px; margin: 18px 0 6px; }

.howto {
  background: #f0f6ff;
  border: 1px solid #d6e4ff;
  border-radius: var(--radius);
  padding: 18px 22px;
  margin-bottom: 26px;
}
.howto h2 { font-size: 17px; margin: 0 0 6px; }
.howto p { margin: 0; color: var(--muted); font-size: 16px; }

.bio {
  display: flex;
  gap: 16px;
  align-items: flex-start;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin-top: 30px;
}
.bio .avatar {
  width: 52px;
  height: 52px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--brand);
  color: #fff;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 19px;
}
.bio .who strong { display: block; font-size: 16px; }
.bio .who p { margin: 4px 0 0; color: var(--muted); font-size: 15px; }

details.faq {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  margin-bottom: 10px;
}
details.faq summary { font-weight: 600; cursor: pointer; color: var(--ink); }
details.faq p { margin: 10px 0 0; color: var(--muted); }

.refs { margin: 0; padding-left: 20px; }
.refs li { margin-bottom: 10px; }

.related-grid { display: grid; gap: 12px; margin-top: 8px; }
.related-grid a.card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 18px;
  color: var(--ink);
  font-weight: 600;
}
.related-grid a.card:hover { border-color: var(--brand); text-decoration: none; }
.related-grid a.card span {
  display: block;
  font-weight: 400;
  color: var(--muted);
  font-size: 14px;
  margin-top: 2px;
}
.related-grid .soon {
  color: var(--muted);
  font-size: 14px;
  padding: 14px 18px;
  border: 1px dashed var(--border);
  border-radius: 10px;
}

/* Amortization schedule */
.schedule { margin: -8px 0 28px; }
.sched-toggle { width: 100%; }
.schedule-body { margin-top: 18px; }
.sched-note {
  font-size: 15px;
  color: var(--ink);
  background: #f0f6ff;
  border: 1px solid #d6e4ff;
  border-radius: 10px;
  padding: 12px 16px;
  margin-bottom: 14px;
}
.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--surface);
  max-height: 520px;
  overflow-y: auto;
}
table.amort {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  min-width: 560px;
}
.amort th,
.amort td {
  padding: 9px 12px;
  text-align: right;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
.amort th:first-child,
.amort td:first-child { text-align: left; }
.amort thead th {
  background: #f7f9fd;
  color: var(--muted);
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  position: sticky;
  top: 0;
  z-index: 1;
}
.amort tr.yr td { font-weight: 600; background: #fbfcff; cursor: pointer; }
.amort tr.yr:hover td { background: #f0f6ff; }
.amort tr.mo td { color: var(--muted); font-weight: 400; }
.amort tr.mo td:first-child { padding-left: 34px; }
.exp {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--brand);
  width: 22px;
  height: 22px;
  border-radius: 6px;
  font-size: 14px;
  line-height: 1;
  cursor: pointer;
  margin-right: 8px;
  font-weight: 700;
}

@media (max-width: 600px) {
  .hero h1 { font-size: 30px; }
  .result, .result.four { grid-template-columns: 1fr; }
  header nav a { margin-left: 14px; }
  table.amort { font-size: 13px; min-width: 520px; }
  .amort th, .amort td { padding: 7px 9px; }
}