/* math.themodel.be — 共通スタイル。対象読者: 定年前後の教養ある大卒者。大きめの文字・高コントラスト・ゆとりある行間。 */
:root {
  --bg: #fffdf8;
  --fg: #1d1d1b;
  --muted: #5b5b57;
  --accent: #1f4e79;      /* 見出し・リンク */
  --accent-soft: #e8eff6;
  --rule: #d8d5cc;
  --def-bg: #f3f7fb;      /* 定義 */
  --thm-bg: #fbf5e6;      /* 定理 */
  --ex-bg: #f2f8f2;       /* 例 */
  --warn-bg: #fdf1f0;     /* 注意・誤解 */
  --max: 44rem;
  --serif-ja: "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif JP", serif;
  --serif-en: Georgia, "Palatino Linotype", "Book Antiqua", "Noto Serif", serif;
  --mono: "SFMono-Regular", Menlo, Consolas, "Liberation Mono", monospace;
}
html { font-size: 19px; }
body { margin: 0; background: var(--bg); color: var(--fg); font-family: var(--serif-en); line-height: 1.95; }
html[lang="ja"] body { font-family: var(--serif-ja); }
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 0.18em; }
a:hover { text-decoration-thickness: 2px; }
.site-header, .site-footer, .chapter, .portal { max-width: var(--max); margin: 0 auto; padding: 0 1.2rem; }
.site-header { display: flex; justify-content: space-between; align-items: baseline; padding-top: 1.2rem; padding-bottom: .6rem; border-bottom: 1px solid var(--rule); }
.brand { font-weight: 700; text-decoration: none; font-size: 1.05rem; letter-spacing: .02em; }
.site-nav a { margin-left: 1rem; font-size: .9rem; }
.breadcrumb { font-size: .85rem; color: var(--muted); margin-top: 1.2rem; }
h1 { font-size: 1.9rem; line-height: 1.35; margin: .6rem 0 .4rem; color: var(--accent); font-weight: 700; }
h2 { font-size: 1.4rem; margin: 2.6rem 0 .8rem; padding-bottom: .3rem; border-bottom: 2px solid var(--accent-soft); color: var(--accent); }
h3 { font-size: 1.15rem; margin: 1.8rem 0 .5rem; }
.meta { color: var(--muted); font-size: .85rem; margin: 0 0 1.4rem; }
.lede { font-size: 1.12rem; background: var(--accent-soft); padding: 1rem 1.2rem; border-radius: 6px; margin: 0 0 1.4rem; }
.lede p { margin: 0; }
.toc { margin: 0 0 2rem; font-size: .95rem; border: 1px solid var(--rule); border-radius: 6px; padding: .5rem 1rem; }
.toc summary { cursor: pointer; font-weight: 700; }
.toc ul { margin: .4rem 0 .2rem; padding-left: 1.3rem; }
p, li { max-width: 40em; }
blockquote { margin: 1rem 0; padding: .2rem 1rem; border-left: 4px solid var(--rule); color: var(--muted); }
table { border-collapse: collapse; margin: 1rem 0; font-size: .95rem; }
th, td { border: 1px solid var(--rule); padding: .4rem .7rem; vertical-align: top; }
th { background: var(--accent-soft); }
.table-wrap { overflow-x: auto; }
code { font-family: var(--mono); font-size: .88em; background: #f2f1ec; padding: .05em .3em; border-radius: 3px; }
pre { overflow-x: auto; background: #f7f6f1; border: 1px solid var(--rule); padding: 1rem; line-height: 1.55; font-size: .82rem; border-radius: 6px; }
pre code { background: none; padding: 0; font-size: inherit; }
.katex-display { overflow-x: auto; overflow-y: hidden; padding: .3rem 0; }
.katex { font-size: 1.08em; }
/* 定義・定理・例・注意 の箱(Markdown の admonition) */
.admonition { margin: 1.4rem 0; padding: .9rem 1.2rem; border-radius: 6px; border: 1px solid var(--rule); }
.admonition-title { font-weight: 700; margin: 0 0 .4rem; }
.admonition p:last-child { margin-bottom: 0; }
.admonition.definition { background: var(--def-bg); }
.admonition.theorem { background: var(--thm-bg); border-color: #e2cf9c; }
.admonition.example { background: var(--ex-bg); }
.admonition.warning, .admonition.misconception { background: var(--warn-bg); }
.admonition.note { background: #f6f6f3; }
.admonition.proof { background: transparent; border-left: 4px solid var(--rule); border-radius: 0; }
.admonition.proof::after { content: "∎"; display: block; text-align: right; color: var(--muted); }
details.solution { margin: .6rem 0 1.2rem; }
details.solution summary { cursor: pointer; color: var(--accent); }
.prereq-list li a.missing, .prereq-list li span.missing { color: var(--muted); }
.lean-badge { display: inline-block; font-size: .8rem; background: #e6f0e6; color: #205020; border-radius: 4px; padding: .1rem .5rem; margin-left: .5rem; vertical-align: middle; }
.site-footer { margin-top: 3.5rem; padding-top: 1rem; padding-bottom: 3rem; border-top: 1px solid var(--rule); color: var(--muted); font-size: .85rem; }
/* ポータル */
.portal h1 { margin-top: 1.4rem; }
.portal .field { margin: 1.6rem 0; }
.portal .field h2 { margin-top: 1.2rem; }
.portal ul { padding-left: 1.2rem; }
.portal li { margin: .35rem 0; }
.portal .level { color: var(--muted); font-size: .85rem; margin-left: .4rem; }
@media (max-width: 600px) {
  html { font-size: 17px; }
  h1 { font-size: 1.55rem; }
  .site-header { flex-direction: column; gap: .3rem; }
  .site-nav a { margin-left: 0; margin-right: 1rem; }
}
@media (prefers-reduced-motion: reduce) { * { scroll-behavior: auto !important; } }