:root {
  --bg: #ffffff;
  --ink: #111111;
  --sub: #333333;
  --line: #dcdcdc;
  --line-light: #eeeeee;
  --hover-bg: #f5f5f5;
  --accent: #0969da;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic", sans-serif;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 18px;
  line-height: 1.85;
}

a { color: var(--accent); text-decoration: underline; text-underline-offset: .25em; }
a:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; border-radius: 2px; }

.wrap { width: min(100% - 2.5rem, 1040px); margin-inline: auto; }

/* Header */
.site {
  background: transparent;
  color: var(--ink);
  padding-block: 2.5rem 1.5rem;
  border-bottom: 1px solid var(--line-light);
}
.site h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.4rem);
  font-weight: 700;
  letter-spacing: -.01em;
  line-height: 1.2;
}

/* Links (Pill Buttons) */
.links {
  display: flex;
  flex-wrap: wrap;
  gap: .6rem;
  margin: 1.2rem 0 0;
  padding: 0;
  list-style: none;
}
.links a {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  padding: .35rem .95rem;
  color: var(--ink);
  font-size: .95rem;
  font-weight: 500;
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: transparent;
  transition: background .15s ease, border-color .15s ease, color .15s ease;
}
.links a:hover {
  background: var(--hover-bg);
  border-color: var(--ink);
}
.links svg { width: 1.1em; height: 1.1em; flex-shrink: 0; }

/* Layout & Navigation */
.layout {
  padding-block: 2rem 4rem;
}
.toc {
  margin: 0 0 2rem;
}
.toc ul {
  display: flex;
  gap: .45rem;
  margin: 0;
  padding: .2rem 0;
  overflow-x: auto;
  list-style: none;
  white-space: nowrap;
  -webkit-overflow-scrolling: touch;
}
.toc a {
  display: inline-block;
  padding: .25rem .85rem;
  color: var(--sub);
  font-size: .95rem;
  line-height: 1.6;
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: transparent;
  transition: background .15s ease, border-color .15s ease, color .15s ease;
}
.toc a:hover, .toc a.on {
  color: var(--ink);
  border-color: var(--ink);
  background: var(--hover-bg);
  font-weight: 600;
}

/* Main Content */
main {
  max-width: 44rem;
}
main h2 {
  margin: 2.8rem 0 .6rem;
  font-size: clamp(1.25rem, 2.4vw, 1.5rem);
  font-weight: 700;
  line-height: 1.4;
  scroll-margin-top: 1.5rem;
  color: var(--ink);
}
main p {
  margin: .4rem 0 1rem;
  color: var(--sub);
  letter-spacing: .01em;
}

/* Topic Navigation Pills (Guide Links) */
.topic-links {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  margin: .8rem 0 2rem;
}
.topic-links a {
  display: inline-flex;
  align-items: center;
  gap: .3rem;
  padding: .25rem .8rem;
  color: var(--ink);
  font-size: .95rem;
  font-weight: 500;
  text-decoration: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: transparent;
  transition: background .15s ease, border-color .15s ease;
}
.topic-links a:hover {
  background: var(--hover-bg);
  border-color: var(--ink);
}

/* Privacy Policy */
#privacypolicy {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}
#privacypolicy h2 {
  margin-top: 0;
  font-size: 1.15rem;
}
#privacypolicy h3 {
  margin: 1.6rem 0 .4rem;
  font-size: .95rem;
  font-weight: 600;
  color: var(--ink);
}
#privacypolicy p {
  font-size: .88rem;
  line-height: 1.8;
}
#privacypolicy .update-date {
  margin-top: 1.2rem;
  font-size: .8rem;
  color: var(--sub);
}

/* Footer */
.site-footer {
  color: var(--sub);
  border-top: 1px solid var(--line-light);
}
.site-footer .wrap {
  padding-block: 1.5rem 3rem;
  font-size: .82rem;
}

/* Desktop 2-column layout */
@media (min-width: 900px) {
  .layout {
    display: grid;
    grid-template-columns: 220px minmax(0, 44rem);
    gap: 4.5rem;
    align-items: start;
  }
  .toc {
    position: sticky;
    top: 2rem;
    align-self: start;
    margin: 0;
  }
  .toc ul {
    display: flex;
    flex-direction: column;
    gap: .4rem;
    overflow: visible;
    white-space: normal;
  }
  .toc a {
    display: block;
    text-align: left;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}