/* 整流版 25記事 共通スタイル(apex.html と整合) */
* { box-sizing: border-box; }
body {
  font-family: "Hiragino Mincho ProN", "Yu Mincho", "Hiragino Sans", serif;
  background: #f7f7f8;
  color: #2c3e50;
  margin: 0 auto;
  padding: 32px 24px 80px;
  line-height: 1.9;
  max-width: 820px;
}
.level-tag {
  display: inline-block;
  background: #1a1a1a;
  color: #fff;
  padding: 4px 12px;
  font-size: 11px;
  letter-spacing: 0.18em;
  margin-bottom: 16px;
  font-family: "Hiragino Sans", sans-serif;
}
h1 {
  font-size: 26px;
  margin: 0 0 8px;
  padding-bottom: 10px;
  border-bottom: 3px solid #3498db;
  line-height: 1.45;
}
.subtitle {
  color: #7f8c8d;
  font-size: 14px;
  margin-bottom: 32px;
  font-style: italic;
}
h2 {
  font-size: 18px;
  font-weight: bold;
  margin: 32px 0 12px;
  padding-left: 12px;
  border-left: 4px solid #3498db;
  color: #2c3e50;
}
h3 {
  font-size: 14px;
  font-weight: bold;
  margin: 20px 0 8px;
  color: #c0392b;
  font-family: "Hiragino Sans", sans-serif;
}
p {
  margin: 0 0 12px;
  font-size: 15px;
  text-align: justify;
}
strong { color: #c0392b; font-weight: bold; }
.eq {
  background: #fff;
  border-left: 4px solid #3498db;
  padding: 14px 18px;
  margin: 16px 0;
  font-family: "JetBrains Mono", "Menlo", monospace;
  font-size: 14px;
  text-align: center;
  border-radius: 4px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
  overflow-x: auto;
}
blockquote {
  border-left: 4px solid #95a5a6;
  padding: 8px 16px;
  margin: 16px 0;
  background: #fafafa;
  font-size: 14px;
  color: #555;
}
ul, ol { margin: 10px 0 16px 8px; padding-left: 22px; }
li { margin-bottom: 6px; font-size: 14px; }
table {
  border-collapse: collapse;
  margin: 18px 0;
  width: 100%;
  font-size: 13px;
  background: #fff;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
}
th, td {
  border: 1px solid #e0e0e0;
  padding: 8px 12px;
  text-align: left;
}
th {
  background: #ecf0f1;
  font-weight: bold;
  font-family: "Hiragino Sans", sans-serif;
}
.boundary-note {
  background: #fff5e6;
  border: 1px solid #e67e22;
  border-radius: 6px;
  padding: 10px 14px;
  margin: 14px 0;
  font-size: 12px;
  color: #6e3500;
}
.boundary-note b { color: #d35400; }
.nav-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 28px;
  padding-bottom: 12px;
  border-bottom: 1px dashed #ccc;
  font-size: 12px;
  font-family: "Hiragino Sans", sans-serif;
}
.nav-bar a {
  color: #7f8c8d;
  text-decoration: none;
  padding: 4px 8px;
  border-radius: 3px;
  transition: all 0.2s;
}
.nav-bar a:hover {
  color: #3498db;
  background: rgba(52, 152, 219, 0.08);
}
.nav-bar a.nav-prev {
  color: #7f8c8d;
}
.nav-bar a.nav-prev:hover {
  color: #3498db;
  background: rgba(52, 152, 219, 0.08);
}
.footer-note {
  margin-top: 48px;
  padding-top: 16px;
  border-top: 1px solid #ddd;
  font-size: 11px;
  color: #95a5a6;
  font-style: italic;
}