h2 {
  font-size: 24px;
  border-bottom: 3px solid #4a90d9;
  padding-bottom: 12px;
}
h3 {
  font-size: 19px;
  margin-top: 48px;
  padding: 8px 12px;
  background: #f0f6fc;
  border-left: 6px solid #4a90d9;
}
h4 {
  font-size: 16px;
  margin-top: 32px;
  padding: 6px 10px;
  background: #f7f7f7;
  border-left: 4px solid #999;
}
.step-num {
  display: inline-block;
  background: #4a90d9;
  color: #fff;
  border-radius: 50%;
  width: 28px;
  height: 28px;
  text-align: center;
  line-height: 28px;
  margin-right: 8px;
  font-size: 15px;
}
.desc {
  margin: 12px 0;
}
figure {
  margin: 16px 0 32px;
  text-align: center;
}
figure img {
  max-width: 100%;
  border: 1px solid #ddd;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
}
figcaption {
  font-size: 13px;
  color: #666;
  margin-top: 6px;
}
.note {
  background: #fff8e1;
  border: 1px solid #f0d78c;
  border-radius: 6px;
  padding: 12px 16px;
  margin: 16px 0;
  font-size: 14px;
}
.note b { color: #a06b00; }
.tip {
  background: #eef7ee;
  border: 1px solid #b9dcb9;
  border-radius: 6px;
  padding: 12px 16px;
  margin: 16px 0;
  font-size: 14px;
}
.tip b { color: #2e7d32; }
code {
  background: #f2f2f2;
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 13px;
}
table {
  border-collapse: collapse;
  width: 100%;
  margin: 16px 0;
  font-size: 14px;
}
table th, table td {
  border: 1px solid #ddd;
  padding: 8px 10px;
  text-align: left;
  vertical-align: top;
}
table th {
  background: #f0f6fc;
}
table td {
  background: #ffffff;
}
nav {
  background: #ffffff;
  border: 1px solid #e0e6ec;
  border-radius: 8px;
  padding: 16px 20px;
  margin: 24px 0;
}
nav a { color: #4a90d9; text-decoration: none; }
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 56px;
  font-size: 14px;
}
.page-nav a { color: #4a90d9; text-decoration: none; }

/* ==========================================================
   index.html 専用スタイル（目次ページのカード一覧レイアウト）
   ========================================================== */
.chapter-list {
  list-style: none;
  padding: 0;
  margin: 24px 0;
}
.chapter-list li {
  margin-bottom: 16px;
  background-color: #ffffff;
}
.chapter-card {
  display: block;
  padding: 16px 20px;
  border: 1px solid #e0e6ec;
  border-radius: 8px;
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.chapter-card:hover {
  border-color: #4a90d9;
  box-shadow: 0 2px 8px rgba(74,144,217,0.15);
}
.chapter-card .chapter-title {
  display: flex;
  align-items: center;
  font-size: 17px;
  font-weight: bold;
  color: #222;
}
.chapter-card .chapter-desc {
  margin: 8px 0 0 36px;
  font-size: 14px;
  color: #555;
}