*, *::before, *::after {
  box-sizing: border-box;
}

:root {
  color-scheme: light;
  --header-bg: #ffffff;
  --header-text: #1a1a1a;
  --page-bg: #ffffff;
  --panel-bg: #f7f7f7;
  --doc-bg: #ffffff;
  --border: #e6e6e6;
  --border-strong: #d2d2d2;
  --text: #1a1a1a;
  --muted: #5c5c5c;
  --accent: #0065b3;
  --accent-hover: #004b86;
  --accent-soft: #e8f3ff;
  --active-indicator: #5c2d91;
  --code-bg: #f6f6f6;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Segoe UI", "Meiryo", "Yu Gothic UI", system-ui, sans-serif;
  font-size: 16px;
  color: var(--text);
  background: var(--page-bg);
  line-height: 1.6;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  height: 54px;
  display: flex;
  align-items: center;
  padding: 0 32px;
  background: var(--header-bg);
  color: var(--header-text);
  border-bottom: 1px solid var(--border);
}

.brand {
  color: inherit;
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
}

.site-shell {
  display: grid;
  grid-template-columns: minmax(260px, 320px) minmax(0, 1fr);
  min-height: calc(100vh - 54px);
}

.side-nav {
  position: sticky;
  top: 54px;
  height: calc(100vh - 54px);
  overflow: auto;
  padding: 18px 16px 32px 24px;
  background: var(--panel-bg);
  border-right: 1px solid var(--border);
}

.nav-tree,
.nav-tree ul {
  list-style: none;
  margin: 0;
  padding-left: 0;
}

.nav-tree ul {
  margin-top: 2px;
  padding-left: 14px;
  border-left: 1px solid var(--border);
}

.nav-link,
.nav-folder summary {
  display: block;
  width: 100%;
  padding: 6px 8px;
  border-radius: 2px;
  color: #333333;
  font-size: 0.875rem;
  line-height: 1.35;
  text-decoration: none;
  cursor: pointer;
}

.nav-link:hover,
.nav-folder summary:hover {
  color: var(--accent-hover);
  background: #eeeeee;
}

.nav-link.is-active {
  position: relative;
  color: var(--text);
  background: #eeeeee;
  font-weight: 600;
}

.nav-link.is-active::before {
  content: "";
  position: absolute;
  top: 6px;
  bottom: 6px;
  left: 0;
  width: 3px;
  background: var(--active-indicator);
}

.doc-content {
  min-width: 0;
  padding: 32px 48px 64px;
}

.doc-article {
  max-width: 960px;
  min-height: calc(100vh - 118px);
  padding: 0 0 64px;
  background: var(--doc-bg);
}

.doc-article:empty::before {
  content: "このドキュメントはまだ空です。";
  color: var(--muted);
}

h1,
h2,
h3,
h4,
h5,
h6 {
  line-height: 1.35;
  margin: 1.8em 0 0.65em;
}

h1 {
  margin-top: 0;
  padding-bottom: 0.45em;
  border-bottom: 1px solid var(--border);
  font-size: 2.25rem;
  font-weight: 600;
}

h2 {
  padding-bottom: 0.35em;
  border-bottom: 1px solid var(--border);
  font-size: 1.55rem;
  font-weight: 600;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  color: var(--accent-hover);
  text-decoration: underline;
}

img,
video {
  max-width: 100%;
  height: auto;
}

figure {
  margin: 24px 0;
}

figcaption {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.92rem;
}

pre {
  overflow: auto;
  padding: 16px;
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 2px;
}

code {
  padding: 0.15em 0.35em;
  background: var(--code-bg);
  border-radius: 2px;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.95em;
}

pre code {
  padding: 0;
  background: transparent;
}

blockquote,
.callout {
  margin: 18px 0;
  padding: 14px 18px;
  background: #f7f7f7;
  border-left: 4px solid var(--accent);
  border-radius: 2px;
}

.callout-title {
  font-weight: 700;
  margin-bottom: 4px;
}

.callout-warning,
.callout-caution,
.callout-danger {
  border-left-color: #b7791f;
  background: #fff8eb;
}

.callout-tip,
.callout-success {
  border-left-color: #2f855a;
  background: #effaf4;
}

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
}

th,
td {
  padding: 9px 12px;
  border: 1px solid var(--border);
  vertical-align: top;
}

th {
  background: #f7f7f7;
  text-align: left;
  font-weight: 600;
}

mark {
  padding: 0.08em 0.2em;
  background: #fff3a3;
  border-radius: 3px;
}

.tag {
  display: inline-block;
  padding: 0 0.4em;
  color: #333333;
  background: var(--accent-soft);
  border-radius: 2px;
  font-size: 0.9em;
}

.missing-link {
  color: #9b2c2c;
  text-decoration: underline wavy;
}

.task-list-item {
  list-style: none;
}

.task-list-item input {
  margin-right: 0.5em;
}

.footnotes {
  margin-top: 48px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.95rem;
}

.math-inline,
.math-block {
  font-family: Cambria Math, "Times New Roman", serif;
  background: #f8fafb;
}

.math-inline {
  padding: 0.05em 0.3em;
  border-radius: 4px;
}

.math-block {
  overflow-x: auto;
  margin: 18px 0;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  white-space: pre;
}

.block-id {
  color: var(--muted);
  font-size: 0.82em;
  text-decoration: none;
}

@media (max-width: 820px) {
  .site-header {
    position: static;
  }

  .site-shell {
    display: block;
  }

  .side-nav {
    position: static;
    width: 100%;
    height: auto;
    max-height: 45vh;
    border-right: 0;
    border-bottom: 1px solid var(--border);
  }

  .doc-content {
    padding: 16px;
  }

  .doc-article {
    padding: 28px 20px 44px;
  }
}