:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --bg-card: #ffffff;
  --fg: #16181d;
  --fg-muted: #565d6b;
  --border: #e3e6eb;
  --accent: #3454d1;
  --accent-fg: #ffffff;
  --tier-a: #1f8a4c;
  --tier-b: #b8860b;
  --tier-c: #b23b3b;
  --code-bg: #0f1115;
  --code-fg: #e6e8ee;
  --radius: 12px;
  --max-width: 1080px;
  font-synthesis: none;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --bg-alt: #15181f;
    --bg-card: #171a21;
    --fg: #e7e9ee;
    --fg-muted: #9aa1b1;
    --border: #262b36;
    --accent: #7f9bff;
    --accent-fg: #0f1115;
    --tier-a: #4fd08a;
    --tier-b: #e0b23a;
    --tier-c: #ea7a7a;
    --code-bg: #05070a;
    --code-fg: #e6e8ee;
  }
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Noto Sans JP", "PingFang SC", "Noto Sans SC", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.6;
}

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

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* --- top bar --- */
.topbar {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.topbar-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.75rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}
.brand {
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: -0.01em;
  white-space: nowrap;
}
.brand code { font-family: inherit; }
.topnav {
  display: flex;
  gap: 1.1rem;
  flex-wrap: wrap;
  font-size: 0.92rem;
  margin-left: auto;
}
.topnav a { color: var(--fg-muted); text-decoration: none; }
.topnav a:hover { color: var(--fg); }
.topnav a[aria-current="page"] { color: var(--fg); font-weight: 600; }

.langswitch {
  display: flex;
  gap: 0.25rem;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.2rem;
}
.langswitch a {
  text-decoration: none;
  background: transparent;
  color: var(--fg-muted);
  font-size: 0.82rem;
  padding: 0.3rem 0.65rem;
  border-radius: 999px;
  cursor: pointer;
}
.langswitch a[aria-current="true"] {
  background: var(--accent);
  color: var(--accent-fg);
  font-weight: 600;
}

/* --- hero --- */
.hero {
  padding: 3.5rem 0 2.5rem;
}
.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  font-weight: 700;
  margin-bottom: 0.9rem;
}
.hero h1 {
  font-size: clamp(1.7rem, 3.4vw, 2.6rem);
  line-height: 1.25;
  margin: 0 0 1rem;
  max-width: 42ch;
}
.hero p {
  font-size: 1.05rem;
  color: var(--fg-muted);
  max-width: 66ch;
  margin: 0 0 1.6rem;
}
.hero-ctas { display: flex; gap: 0.75rem; flex-wrap: wrap; }

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.05rem;
  border-radius: 999px;
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 600;
  border: 1px solid var(--border);
  color: var(--fg);
}
.btn.primary {
  background: var(--accent);
  color: var(--accent-fg);
  border-color: var(--accent);
}
.btn:hover { filter: brightness(1.06); }

.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-top: 2.2rem;
}
.stat {
  background: var(--bg-card);
  padding: 1rem 1.1rem;
}
.stat b {
  display: block;
  font-size: 1.5rem;
  letter-spacing: -0.02em;
}
.stat span {
  font-size: 0.82rem;
  color: var(--fg-muted);
}

/* --- sections --- */
section { padding: 2.75rem 0; }
section + section { border-top: 1px solid var(--border); }
.section-head { max-width: 70ch; margin-bottom: 1.75rem; }
.section-head h2 {
  font-size: 1.5rem;
  margin: 0 0 0.5rem;
  letter-spacing: -0.01em;
}
.section-head p { color: var(--fg-muted); margin: 0; }

/* --- use cases --- */
.usecases {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}
.usecase-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.2rem;
}
.usecase-card .ico { font-size: 1.5rem; }
.usecase-card h3 { margin: 0.5rem 0 0.4rem; font-size: 1.02rem; }
.usecase-card p { margin: 0; color: var(--fg-muted); font-size: 0.92rem; }

.contract-list {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: rule;
  display: grid;
  gap: 0.6rem;
}
.contract-list li {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.7rem 0.85rem;
  font-size: 0.88rem;
  color: var(--fg-muted);
}
.contract-list li b { color: var(--fg); }

/* --- formats --- */
.tier-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.2rem;
}
.tier-chip {
  display: flex;
  gap: 0.5rem;
  align-items: flex-start;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.55rem 0.75rem;
  font-size: 0.82rem;
  max-width: 320px;
}
.tier-badge {
  flex: none;
  width: 1.5rem;
  height: 1.5rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.82rem;
  color: #fff;
}
.tier-badge.A { background: var(--tier-a); }
.tier-badge.B { background: var(--tier-b); }
.tier-badge.C { background: var(--tier-c); }
.tier-chip span { color: var(--fg-muted); }

.table-scroll {
  overflow-x: auto;
  border: 1px solid var(--border);
  border-radius: var(--radius);
}
table.formats {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  min-width: 640px;
}
table.formats th, table.formats td {
  padding: 0.65rem 0.85rem;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--border);
}
table.formats thead th {
  background: var(--bg-alt);
  font-size: 0.76rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--fg-muted);
  position: sticky;
  top: 0;
}
table.formats tbody tr:last-child td { border-bottom: none; }
table.formats .ext code {
  background: var(--bg-alt);
  padding: 0.1rem 0.35rem;
  border-radius: 6px;
  font-size: 0.82rem;
}
table.formats .cat-heading td {
  background: var(--bg-alt);
  font-weight: 700;
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--accent);
}
.tier-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 1.5rem;
  padding: 0.1rem 0.4rem;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.78rem;
  color: #fff;
}
.tier-pill.A { background: var(--tier-a); }
.tier-pill.B { background: var(--tier-b); }
.tier-pill.C { background: var(--tier-c); }
.tier-pill.none { background: transparent; color: var(--fg-muted); font-weight: 400; }
.notes-cell { color: var(--fg-muted); max-width: 42ch; }

/* --- gallery --- */
.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1rem;
}
.gallery-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  overflow: hidden;
  display: flex;
  flex-direction: column;
}
.gallery-thumb {
  aspect-ratio: 4 / 3;
  background:
    linear-gradient(45deg, var(--bg-alt) 25%, transparent 25%) 0 0/16px 16px,
    linear-gradient(-45deg, var(--bg-alt) 25%, transparent 25%) 0 0/16px 16px,
    linear-gradient(45deg, transparent 75%, var(--bg-alt) 75%) 0 0/16px 16px,
    linear-gradient(-45deg, transparent 75%, var(--bg-alt) 75%) 0 0/16px 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.6rem;
}
.gallery-thumb img { max-width: 100%; max-height: 100%; }
.gallery-body { padding: 0.75rem 0.9rem 0.9rem; }
.gallery-body h3 {
  margin: 0 0 0.15rem;
  font-size: 0.95rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.gallery-body .ext-tag {
  font-family: monospace;
  font-size: 0.75rem;
  color: var(--fg-muted);
}
.gallery-links {
  display: flex;
  gap: 0.8rem;
  font-size: 0.8rem;
  margin-top: 0.5rem;
}

/* --- module usage --- */
.usage-tabs {
  display: flex;
  gap: 0.4rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}
.usage-tabs button {
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--fg-muted);
  padding: 0.45rem 1rem;
  border-radius: 999px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
}
.usage-tabs button[aria-selected="true"] {
  background: var(--fg);
  color: var(--bg);
  border-color: var(--fg);
}
.usage-panel { display: grid; gap: 1rem; }
.usage-panel[hidden] { display: none; }
.usage-snippet {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  padding: 1rem 1.1rem 1.1rem;
}
.usage-snippet h3 {
  margin: 0 0 0.6rem;
  font-size: 0.92rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.usage-snippet .lang-tag {
  font-family: monospace;
  font-size: 0.7rem;
  color: var(--fg-muted);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.05rem 0.4rem;
  font-weight: 400;
}
.usage-snippet pre { margin: 0; white-space: pre-wrap; word-break: break-word; }

pre {
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 0.85rem 1rem;
  border-radius: 9px;
  overflow-x: auto;
  font-size: 0.82rem;
  margin: 0;
}
code { font-family: "SFMono-Regular", Consolas, Menlo, monospace; }

/* --- footer --- */
footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0 3rem;
  color: var(--fg-muted);
  font-size: 0.86rem;
}
.footer-links {
  display: flex;
  gap: 1.1rem;
  flex-wrap: wrap;
  margin-bottom: 0.8rem;
}
.footer-links a { color: var(--fg); text-decoration: none; }
.footer-links a:hover { text-decoration: underline; }

.visually-hidden {
  position: absolute;
  width: 1px; height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

/* --- skip link --- */
.skip-link {
  position: absolute;
  left: 1rem;
  top: -3rem;
  background: var(--accent);
  color: var(--accent-fg);
  padding: 0.4rem 0.8rem;
  border-radius: 8px;
  z-index: 10;
}
.skip-link:focus { top: 0.5rem; }

/* --- linked cards (home) --- */
.usecase-card.linked { display: block; transition: border-color 0.15s; }
.usecase-card.linked:hover { border-color: var(--accent); }
.text-links {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1.4rem;
  margin: 1.2rem 0 0;
  font-size: 0.92rem;
  font-weight: 600;
}
.text-links a { text-decoration: none; }
.text-links a:hover { text-decoration: underline; }
.next-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 1rem;
}
.next-card {
  display: block;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-alt);
  padding: 1.1rem 1.2rem;
  transition: border-color 0.15s;
}
.next-card:hover { border-color: var(--accent); }
.next-card h3 { margin: 0 0 0.35rem; font-size: 1rem; color: var(--accent); }
.next-card p { margin: 0; color: var(--fg-muted); font-size: 0.9rem; }

/* --- pages with a sidebar --- */
.page-grid {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 2.75rem;
  padding-top: 2.25rem;
  padding-bottom: 3rem;
}
.sidenav {
  position: sticky;
  top: 1.25rem;
  align-self: start;
  max-height: calc(100vh - 2.5rem);
  overflow-y: auto;
  font-size: 0.88rem;
}
.sidenav > summary { display: none; }
.sidenav ol { list-style: none; margin: 0; padding: 0; border-left: 1px solid var(--border); }
.sidenav a {
  display: block;
  padding: 0.35rem 0 0.35rem 0.9rem;
  margin-left: -1px;
  border-left: 2px solid transparent;
  color: var(--fg-muted);
  text-decoration: none;
  line-height: 1.4;
}
.sidenav a:hover { color: var(--fg); }
.sidenav a[aria-current="true"] { color: var(--accent); border-left-color: var(--accent); font-weight: 600; }

.page-head { margin-bottom: 1.5rem; max-width: 70ch; }
.page-head h1 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  line-height: 1.25;
  margin: 0 0 0.6rem;
  letter-spacing: -0.01em;
}
.page-head p { color: var(--fg-muted); font-size: 1.02rem; margin: 0; }

.doc-section { padding: 1.9rem 0; scroll-margin-top: 1rem; }
.doc-section + .doc-section { border-top: 1px solid var(--border); }
.doc-section h2 {
  font-size: 1.3rem;
  margin: 0 0 0.7rem;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.doc-section > p { max-width: 70ch; }
.doc-section p.lead { color: var(--fg-muted); margin-top: 0; }
.h-ico { font-size: 1.3rem; }
.bullets { padding-left: 1.2rem; max-width: 70ch; }
.bullets li { margin: 0.35rem 0; }
.doc-section pre { margin: 0.9rem 0; }

.detail-grid {
  display: grid;
  grid-template-columns: 11rem minmax(0, 1fr);
  gap: 0.7rem 1.25rem;
  margin: 1rem 0 0;
  max-width: 78ch;
}
.detail-grid dt { font-weight: 700; font-size: 0.85rem; color: var(--accent); padding-top: 0.1rem; }
.detail-grid dd { margin: 0; }

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1rem;
  margin-top: 1rem;
}
.info-card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  padding: 1rem 1.1rem;
  display: flex;
  flex-direction: column;
}
.info-card h3 { margin: 0 0 0.4rem; font-size: 0.98rem; }
.info-card p { margin: 0 0 0.8rem; color: var(--fg-muted); font-size: 0.9rem; flex: 1; }
.info-card pre { margin: 0; }

.contract-list li { counter-increment: rule; }
.contract-list li::before { content: counter(rule) ". "; font-weight: 700; color: var(--fg); }

/* --- formats page --- */
.how-box {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.3rem 1.2rem;
  margin-bottom: 1.5rem;
}
.how-box h2 { font-size: 1.05rem; margin: 0 0 0.4rem; }
.how-box h3 { font-size: 0.9rem; margin: 1rem 0 0.6rem; }
.how-box ul { margin: 0; padding-left: 1.2rem; }
.how-box li { margin: 0.25rem 0; font-size: 0.92rem; }
.how-box .tier-legend { margin-bottom: 0; }

.search-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem 1rem;
  margin-bottom: 0.5rem;
}
.search-bar > label:first-child { font-weight: 700; font-size: 0.92rem; flex-basis: 100%; }
.search-bar input[type="search"] {
  flex: 1 1 260px;
  font: inherit;
  padding: 0.6rem 0.85rem;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--bg-card);
  color: var(--fg);
}
.search-bar input[type="search"]:focus { outline: 2px solid var(--accent); outline-offset: 1px; }
.search-bar .check { display: inline-flex; align-items: center; gap: 0.4rem; font-size: 0.9rem; cursor: pointer; }
.result-count { color: var(--fg-muted); font-size: 0.88rem; margin-left: auto; }
.empty-note { color: var(--fg-muted); }
.count-chip {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--fg-muted);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.05rem 0.55rem;
}
.format-group .table-scroll { margin-top: 0.4rem; }

@media (max-width: 860px) {
  .page-grid { grid-template-columns: minmax(0, 1fr); gap: 0.5rem; padding-top: 1.25rem; }
  .sidenav {
    position: static;
    max-height: none;
    border: 1px solid var(--border);
    border-radius: 10px;
    background: var(--bg-alt);
  }
  .sidenav > summary { display: block; padding: 0.7rem 1rem; font-weight: 600; cursor: pointer; }
  .sidenav nav { padding: 0 1rem 0.8rem; }
  .detail-grid { grid-template-columns: 1fr; gap: 0.2rem; }
  .detail-grid dd { margin-bottom: 0.7rem; }
  .result-count { margin-left: 0; }
}