:root {
  --brand: #1f6feb;
  --brand-dark: #1556c4;
  --ink: #1b1f23;
  --muted: #586069;
  --bg: #ffffff;
  --surface: #f6f8fa;
  --border: #d0d7de;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}
.container { max-width: 960px; margin: 0 auto; padding: 0 20px; }

.site-header {
  border-bottom: 1px solid var(--border);
  background: var(--surface);
}
.site-header .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 56px;
}
.brand { font-size: 1.25rem; font-weight: 600; color: var(--ink); text-decoration: none; }
.brand strong { color: var(--brand); }
.nav a { margin-left: 16px; color: var(--muted); text-decoration: none; }
.nav a:hover { color: var(--brand); }

main { padding: 40px 0; min-height: 60vh; }
h1 { font-size: 2rem; margin: 0 0 8px; }
.subtitle { color: var(--muted); margin-top: 0; }

.grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px; margin-top: 24px;
}
.card {
  display: block; padding: 20px; border: 1px solid var(--border);
  border-radius: 8px; color: var(--ink); text-decoration: none;
  background: var(--surface);
}
.card:hover { border-color: var(--brand); }
.card h3 { margin: 0 0 6px; font-size: 1rem; }
.card p { margin: 0; color: var(--muted); font-size: 0.9rem; }

.toolbox {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 8px; padding: 24px; margin: 24px 0;
}
.toolbox label { display: block; margin: 12px 0 4px; font-weight: 600; }
.toolbox input, .toolbox select {
  width: 100%; padding: 8px 10px; border: 1px solid var(--border);
  border-radius: 6px; font-size: 1rem;
}
.btn {
  margin-top: 16px; padding: 10px 18px; border: 0; border-radius: 6px;
  background: var(--brand); color: #fff; font-size: 1rem; cursor: pointer;
}
.btn:hover { background: var(--brand-dark); }
.result {
  margin-top: 20px; padding: 16px; border-radius: 6px;
  background: #eaf2ff; border: 1px solid #b6d2ff; display: none;
}
.result .big { font-size: 1.75rem; font-weight: 700; color: var(--brand-dark); }
.chart-box {
  margin-top: 20px; padding: 16px; border-radius: 6px;
  background: #fff; border: 1px solid var(--border);
}
.chart-box canvas { max-height: 280px; }
.newsletter {
  margin-top: 40px; padding: 24px; border-radius: 8px;
  background: var(--surface); border: 1px solid var(--border);
}
.newsletter h2 { margin-top: 0; font-size: 1.25rem; }
.newsletter form { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 12px; }
.newsletter input[type="email"] {
  flex: 1; min-width: 220px; padding: 10px; border: 1px solid var(--border);
  border-radius: 6px; font-size: 1rem;
}
.newsletter .btn { margin-top: 0; }
.newsletter .fine { color: var(--muted); font-size: 0.85rem; margin-bottom: 0; }

.amort-table {
  width: 100%; border-collapse: collapse; font-size: 0.9rem;
}
.amort-table th, .amort-table td {
  padding: 6px 8px; text-align: right; border-bottom: 1px solid var(--border);
}
.amort-table th:first-child, .amort-table td:first-child { text-align: left; }
.amort-table thead th { background: var(--surface); }
#tableBox { max-height: 420px; overflow: auto; }

.site-footer {
  border-top: 1px solid var(--border); color: var(--muted);
  padding: 24px 0; font-size: 0.9rem;
}

.share {
  margin-top: 32px; padding: 16px 0; border-top: 1px solid var(--border);
}
.share h3 { font-size: 0.9rem; color: var(--muted); margin: 0 0 10px; font-weight: 600; }
.share-buttons { display: flex; gap: 8px; flex-wrap: wrap; }
.share-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 14px; border-radius: 6px; border: 1px solid var(--border);
  background: var(--surface); color: var(--ink); font-size: 0.85rem;
  text-decoration: none; cursor: pointer;
}
.share-btn:hover { border-color: var(--brand); }
.share-btn .icon { width: 14px; height: 14px; }
.copy-confirm { color: var(--brand); font-size: 0.8rem; margin-left: 8px; }