:root {
  --bg: #000000;
  --surface: #1c1c1e;
  --surface-2: #2c2c2e;
  --fg: #ffffff;
  --fg-dim: #8e8e93;
  --accent: #ff0033;
  --link: #4da3ff;
  --border: #2c2c2e;
  --max: 760px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Hiragino Sans", "Noto Sans JP", sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---- Header ---- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: rgba(0, 0, 0, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
}
.header-inner {
  max-width: var(--max);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 15px;
  text-decoration: none;
  color: var(--fg);
}
.brand-mark {
  width: 26px;
  height: 26px;
  border-radius: 7px;
  background: var(--accent);
  display: grid;
  place-items: center;
}
.brand-mark svg { width: 16px; height: 16px; fill: #fff; }

.header-nav { display: flex; gap: 20px; font-size: 14px; }
.header-nav a {
  color: var(--fg-dim);
  text-decoration: none;
  transition: color 0.15s;
}
.header-nav a:hover { color: var(--fg); }

/* ---- Document ---- */
.doc {
  max-width: var(--max);
  margin: 0 auto;
  padding: 56px 24px 80px;
}

.doc h1 {
  font-size: clamp(28px, 5vw, 40px);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 8px;
}

.updated {
  color: var(--fg-dim);
  font-size: 14px;
  margin-bottom: 32px;
}

.doc section {
  padding-top: 40px;
  margin-top: 40px;
  border-top: 1px solid var(--border);
}
.doc section:first-of-type {
  border-top: none;
  margin-top: 24px;
  padding-top: 0;
}

.doc h2 {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 16px;
}

.doc h3 {
  font-size: 17px;
  font-weight: 600;
  margin-top: 28px;
  margin-bottom: 10px;
}

.doc p {
  margin-bottom: 14px;
  color: #d8d8dc;
}

.doc ul, .doc ol {
  margin: 0 0 16px 22px;
  color: #d8d8dc;
}
.doc li { margin-bottom: 6px; }

.doc a { color: var(--link); }

.doc code {
  background: var(--surface);
  padding: 2px 7px;
  border-radius: 5px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.88em;
  color: var(--fg);
}

/* ---- 目次 ---- */
.toc {
  background: var(--surface);
  border-radius: 14px;
  padding: 20px 24px;
  margin-bottom: 8px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.toc a {
  color: var(--link);
  text-decoration: none;
  font-size: 14px;
}
.toc a:hover { text-decoration: underline; }

/* ---- 補足ボックス ---- */
.note {
  background: var(--surface);
  border-left: 3px solid var(--accent);
  border-radius: 0 12px 12px 0;
  padding: 18px 22px;
  margin: 20px 0;
}
.note strong {
  display: block;
  margin-bottom: 6px;
  font-size: 15px;
}
.note p {
  margin: 0;
  font-size: 14px;
  color: var(--fg-dim);
}

/* ---- 要約ボックス ---- */
.summary-box {
  background: var(--surface);
  border-radius: 14px;
  padding: 24px;
}
.summary-box p {
  font-weight: 600;
  font-size: 16px;
  color: var(--fg);
  margin-bottom: 12px;
}
.summary-box ul {
  margin: 0 0 0 20px;
  color: var(--fg-dim);
  font-size: 14px;
}

/* ---- 定義リスト ---- */
.def-list {
  background: var(--surface);
  border-radius: 14px;
  padding: 8px 24px;
  margin: 16px 0;
}
.def-list dt {
  font-weight: 600;
  font-size: 15px;
  margin-top: 16px;
}
.def-list dd {
  color: var(--fg-dim);
  font-size: 14px;
  margin: 4px 0 16px;
}

/* ---- Footer ---- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 40px 0 56px;
  font-size: 13px;
  color: var(--fg-dim);
}
.footer-inner {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  justify-content: space-between;
  align-items: center;
}
.footer-links { display: flex; gap: 20px; }
.footer-links a {
  color: var(--fg-dim);
  text-decoration: none;
}
.footer-links a:hover { color: var(--fg); }

@media (max-width: 640px) {
  .header-nav { gap: 14px; font-size: 13px; }
  .doc { padding: 40px 20px 64px; }
}