:root{
  --bg:#f5f7fb;
  --card:#ffffff;
  --muted:#6b7280;
  --accent:#1464f4;
  --radius:10px;
}
*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font-family:Segoe UI, Roboto, "Helvetica Neue", Arial, sans-serif;
  background:var(--bg);
  color:#111827;
}
.site-header{
  display:flex;
  align-items:center;
  justify-content:space-between;
  padding:18px 24px;
  background:linear-gradient(90deg, #fff, #f8fafc);
  box-shadow:0 1px 0 rgba(16,24,40,0.04);
}
.site-title{margin:0;font-size:18px}
.site-nav{display:flex;gap:12px}
.nav-link{color:var(--muted);text-decoration:none;padding:8px 12px;border-radius:8px}
.nav-link.active{background:rgba(20,100,244,0.08);color:var(--accent);font-weight:600}
.container{max-width:920px;margin:28px auto;padding:0 16px}
.card{background:var(--card);border-radius:var(--radius);padding:20px;box-shadow:0 6px 18px rgba(15,23,42,0.06)}
.card-title{margin-top:0;margin-bottom:12px}
.calc-form{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
.calc-form label{display:flex;flex-direction:column;font-size:14px;color:var(--muted)}
.calc-form input[type=number]{padding:10px;border:1px solid #e6e9ef;border-radius:8px;margin-top:6px}
.form-actions{grid-column:1/-1;display:flex;gap:8px;justify-content:flex-start;margin-top:6px}
.btn{background:var(--accent);color:#fff;padding:10px 14px;border-radius:8px;border:0;cursor:pointer}
.btn-ghost{background:transparent;color:var(--accent);border:1px solid rgba(20,100,244,0.12)}
.result{margin-top:14px;padding:12px;border-radius:8px;background:#f8fafc;color:#0f172a}
/* 摊还表样式 */
.amort-table{width:100%;border-collapse:collapse;font-size:13px}
.amort-table th,.amort-table td{padding:8px 10px;border-bottom:1px solid #eef2f7;text-align:right}
.amort-table th{background:#fbfdff;position:sticky;top:0;text-align:center}
.amort-wrap{overflow:auto}
.amort-note{font-size:13px;color:var(--muted);margin-top:8px}
fieldset{border:1px solid #eef2f7;padding:12px;border-radius:8px;margin:0}
legend{padding:0 6px;color:var(--muted)}
@media (max-width:560px){.calc-form{grid-template-columns:1fr}.site-header{flex-direction:column;align-items:flex-start;gap:8px}}