:root {
  --blue: #0d3b66;
  --blue-light: #145374;
  --bg: #f6f8fb;
  --card: #fff;
  --border: #c9d6e3;
  --text: #1a1a1a;
  --muted: #555;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Noto Sans", "Hiragino Sans", "Yu Gothic", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.5;
  color: var(--text);
  background: var(--bg);
}

.site-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 20px;
  padding: 12px 24px;
  background: var(--card);
  border-bottom: 1px solid var(--border);
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--blue);
  font-weight: 700;
  font-size: 1.1rem;
}
.nav-main {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  flex: 1;
}
.nav-main a {
  color: var(--blue-light);
  text-decoration: none;
  font-size: 0.92rem;
}
.nav-main a:hover { text-decoration: underline; }
.nav-cta { font-weight: 600; }
.lang-switch a {
  text-decoration: none;
  color: var(--muted);
  font-size: 0.9rem;
}
.lang-switch a.active { color: var(--blue); font-weight: 700; }

.site-main {
  max-width: 960px;
  margin: 0 auto;
  padding: 28px 20px 48px;
}
.hero h1 { color: var(--blue); font-size: 1.75rem; margin: 0 0 12px; }
.lead { color: var(--muted); font-size: 1.05rem; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 20px; }

.btn {
  display: inline-block;
  padding: 10px 18px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--blue);
  text-decoration: none;
  font-size: 0.95rem;
  cursor: pointer;
}
.btn.primary {
  background: var(--blue);
  color: #fff;
  border-color: var(--blue);
}

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 32px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 18px;
  text-decoration: none;
  color: inherit;
}
.card h2 { margin: 0 0 8px; font-size: 1.1rem; color: var(--blue); }
.card p { margin: 0; font-size: 0.9rem; color: var(--muted); }

.commercial-embed .commercial-doc {
  background: var(--card);
  padding: 16px 20px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.95rem;
}
.commercial-embed .commercial-doc table { font-size: 0.85rem; }
.commercial-contact-hint {
  margin: 0 0 16px;
  padding: 12px 14px;
  background: #eef4fa;
  border-radius: 6px;
  font-size: 0.92rem;
}
.commercial-contact-hint a { font-weight: 600; }
.error { color: #a11; font-weight: 600; }
.sales-cta { margin-top: 20px; display: flex; flex-wrap: wrap; gap: 10px; }

.lesson h1 { color: var(--blue); }
.lesson pre, .lesson code { background: #eef4fa; font-size: 0.88rem; }
.lesson pre { padding: 12px; overflow-x: auto; border-radius: 6px; }

.quiz fieldset {
  border: 1px solid var(--border);
  border-radius: 6px;
  margin: 14px 0;
  padding: 12px;
}
.quiz label { display: block; margin: 6px 0; }

.form-eval label, .form-contact label {
  display: block;
  margin: 12px 0;
}
.form-eval input, .form-contact input, .form-contact textarea, .form-contact select {
  display: block;
  width: 100%;
  max-width: 420px;
  margin-top: 4px;
  padding: 8px;
}

.hint { font-size: 0.9rem; color: var(--muted); }

.site-footer {
  text-align: center;
  padding: 24px;
  font-size: 0.85rem;
  color: var(--muted);
  border-top: 1px solid var(--border);
}
.site-footer a { color: var(--blue-light); }