:root {
  color-scheme: light;
  --bg: #f7f4ee;
  --panel: #fffdf8;
  --text: #202532;
  --muted: #6b7280;
  --line: #ded7ca;
  --accent: #0f666d;
  --accent-soft: #e7f4f2;
  --code-bg: #101828;
  --code-text: #f8fafc;
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: #11151c;
  --panel: #171d27;
  --text: #edf2f7;
  --muted: #aab4c2;
  --line: #2b3544;
  --accent: #5dd6c9;
  --accent-soft: #193b3d;
  --code-bg: #070a10;
  --code-text: #f8fafc;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    radial-gradient(circle at top left, color-mix(in srgb, var(--accent) 12%, transparent), transparent 34rem),
    var(--bg);
  color: var(--text);
  font-family: "Hiragino Sans", "Yu Gothic", "Noto Sans JP", sans-serif;
  line-height: 1.8;
}
a { color: var(--accent); text-decoration-thickness: 0.08em; text-underline-offset: 0.18em; }
.layout-shell { display: grid; grid-template-columns: minmax(17rem, 21rem) 1fr; min-height: 100vh; }
.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  overflow: auto;
  border-right: 1px solid var(--line);
  background: color-mix(in srgb, var(--panel) 86%, transparent);
  padding: 1rem 0.85rem;
}
.sidebar-header { display: flex; align-items: center; gap: 0.8rem; justify-content: space-between; margin-bottom: 1rem; padding: 0 0.25rem; }
.sidebar h1 { font-size: 1.02rem; line-height: 1.2; margin: 0; white-space: nowrap; letter-spacing: -0.02em; }
.sidebar-home-link { color: var(--text); text-decoration: none; }
.nav-list { display: grid; gap: 0.25rem; font-family: inherit; }
.nav-tree, .nav-children { list-style: none; padding: 0; margin: 0; }
.nav-home, .nav-item a, .nav-group-toggle {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 0.55rem;
  min-height: 1.9rem;
  border: 0;
  border-radius: 0.28rem;
  background: transparent;
  color: var(--text);
  font: inherit;
  text-align: left;
  text-decoration: none;
  cursor: pointer;
}
.nav-home { padding: 0.34rem 0.45rem; font-weight: 800; }
.nav-item a { padding: 0.25rem 0.45rem; font-size: 0.9rem; line-height: 1.35; }
.nav-group-toggle { justify-content: space-between; padding: 0.38rem 0.45rem; font-weight: 800; }
.nav-group-label { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.nav-group-icon {
  width: 0.42rem;
  height: 0.42rem;
  flex: 0 0 auto;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: rotate(-45deg);
  transition: transform .18s ease;
  opacity: 0.72;
}
.nav-group.is-open > .nav-group-toggle .nav-group-icon { transform: rotate(45deg); }
.nav-children { overflow: hidden; transition: max-height .22s ease; }
.nav-home:hover, .nav-item a:hover, .nav-group-toggle:hover,
.nav-home.active, .nav-item a.active { background: var(--accent-soft); color: var(--accent); }
.nav-group.depth-1 { border-top: 1px solid color-mix(in srgb, var(--line) 70%, transparent); margin-top: 0.35rem; padding-top: 0.35rem; }
.nav-item.depth-0 { display: none; }
.nav-item.depth-1 a { padding-left: 0.65rem; }
.nav-item.depth-2 a, .nav-group.depth-2 > .nav-group-toggle { padding-left: 1.05rem; }
.nav-item.depth-3 a, .nav-group.depth-3 > .nav-group-toggle { padding-left: 1.45rem; }
.nav-item.depth-4 a, .nav-group.depth-4 > .nav-group-toggle { padding-left: 1.85rem; }
.nav-group.depth-1 > .nav-group-toggle {
  color: var(--accent);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.content-shell { min-width: 0; padding: clamp(1rem, 4vw, 4rem); }
.content {
  width: min(100%, 58rem);
  margin: 0 auto;
  background: color-mix(in srgb, var(--panel) 76%, transparent);
  border: 1px solid color-mix(in srgb, var(--line) 65%, transparent);
  border-radius: 1rem;
  padding: clamp(1.4rem, 4vw, 3rem);
  box-shadow: 0 1rem 4rem color-mix(in srgb, #000 9%, transparent);
}
.prose h1 { font-size: clamp(2.1rem, 6vw, 4.8rem); line-height: 1.04; margin: 0 0 1.8rem; letter-spacing: -0.06em; }
.prose h2 { border-top: 1px solid color-mix(in srgb, var(--line) 75%, transparent); padding-top: 1.5rem; margin-top: 2.4rem; font-size: clamp(1.5rem, 3vw, 2.2rem); line-height: 1.25; }
.prose h3 { margin-top: 2rem; font-size: 1.28rem; }
.prose img, .prose svg { max-width: 100%; }
.page-toc { background: color-mix(in srgb, var(--accent-soft) 72%, var(--panel)); padding: 1rem 1.2rem; margin-bottom: 2rem; border-radius: 0.32rem; }
.page-toc h2 { margin: 0 0 0.55rem; padding: 0; border: 0; font-size: 1.1rem; }
.page-toc ul { margin: 0; padding: 0; list-style: none; columns: 2 16rem; }
.page-toc li { break-inside: avoid; margin: 0.12rem 0; }
.page-toc a { color: var(--text); text-decoration: none; }
.page-toc a:hover { color: var(--accent); text-decoration: underline; }
pre { overflow: auto; background: var(--code-bg); color: var(--code-text); padding: 1rem; border-radius: 0; font-size: 0.95rem; line-height: 1.65; }
code { font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace; font-size: 0.95em; }
:not(pre) > code { background: color-mix(in srgb, var(--accent) 12%, transparent); padding: 0.08em 0.25em; border-radius: 0.2rem; }
table { width: 100%; border-collapse: collapse; display: block; overflow-x: auto; }
th, td { border: 1px solid var(--line); padding: 0.55rem 0.7rem; }
blockquote { border-left: 0.25rem solid var(--accent); margin-left: 0; padding-left: 1rem; color: var(--muted); }
.callout { background: var(--accent-soft); padding: 1rem 1.1rem; border-radius: 0.3rem; margin: 1.2rem 0; }
.callout-title { margin: 0 0 0.35rem; color: var(--accent); font-weight: 800; }
.theme-toggle, .sidebar-toggle { border: 1px solid var(--line); background: var(--panel); color: var(--text); border-radius: 999px; padding: 0.35rem 0.65rem; cursor: pointer; }
.theme-toggle-track { display: inline-flex; align-items: center; gap: 0.35rem; }
.sidebar-toggle { display: none; margin-bottom: 1rem; }
.mermaid { background: transparent; color: var(--text); text-align: center; }
@media (max-width: 860px) {
  .layout-shell { display: block; }
  .sidebar { position: fixed; z-index: 20; inset: 0 auto 0 0; width: min(86vw, 22rem); transform: translateX(-100%); transition: transform .2s ease; }
  body.sidebar-open .sidebar { transform: translateX(0); }
  .sidebar-toggle { display: inline-block; }
  .content-shell { padding: 1rem; }
  .content { border-radius: 0.6rem; }
}