:root {
  color-scheme: light;
  --paper: #f5f5f0;
  --ink: #1a1a1a;
  --muted: #66645f;
  --line: rgba(26, 26, 26, 0.16);
  --accent: #ff4500;
}

* {
  box-sizing: border-box;
}

html,
body {
  min-width: 320px;
  min-height: 100%;
  margin: 0;
  background: var(--paper);
}

body {
  color: var(--ink);
  font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, "PingFang SC", "Noto Sans CJK SC", sans-serif;
  line-height: 1.75;
}

a {
  color: inherit;
  text-decoration-color: rgba(26, 26, 26, 0.35);
  text-underline-offset: 4px;
}

a:hover,
a:focus-visible {
  color: var(--accent);
  text-decoration-color: currentColor;
}

.site-nav,
.document,
.site-footer {
  width: min(760px, calc(100% - 48px));
  margin-inline: auto;
}

.site-nav {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  padding: 32px 0 24px;
  border-bottom: 1px solid var(--line);
}

.site-nav a {
  text-decoration: none;
}

.brand {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.brand::after {
  color: var(--accent);
  content: ".";
}

.site-nav div {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  color: var(--muted);
  font-size: 0.875rem;
}

.site-nav [aria-current="page"] {
  color: var(--ink);
}

.document {
  padding: 72px 0 80px;
}

.document header {
  padding-bottom: 48px;
  border-bottom: 2px solid var(--ink);
}

h1 {
  max-width: 12ch;
  margin: 0;
  font-size: clamp(2.5rem, 7vw, 4.75rem);
  line-height: 1.05;
  letter-spacing: -0.06em;
}

.english-title {
  margin: 14px 0 0;
  color: var(--accent);
  font-weight: 600;
}

.updated {
  margin: 32px 0 0;
  color: var(--muted);
  font-size: 0.875rem;
}

.summary {
  max-width: 640px;
  margin: 24px 0 0;
  font-size: 1.125rem;
}

.document section {
  display: grid;
  grid-template-columns: minmax(150px, 0.34fr) minmax(0, 1fr);
  gap: 40px;
  padding: 36px 0;
  border-bottom: 1px solid var(--line);
}

h2 {
  margin: 0;
  font-size: 1rem;
  line-height: 1.5;
}

.section-body p {
  margin: 0 0 16px;
}

.section-body p:last-child {
  margin-bottom: 0;
}

.section-body [lang="en"] {
  color: var(--muted);
  font-size: 0.925rem;
}

.contact-link {
  display: inline-block;
  margin-top: 8px;
  color: var(--accent);
  font-weight: 600;
}

.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 24px;
  padding: 24px 0 40px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 0.8rem;
}

@media (max-width: 640px) {
  .site-nav,
  .document,
  .site-footer {
    width: min(100% - 32px, 760px);
  }

  .site-nav {
    align-items: flex-start;
    flex-direction: column;
  }

  .document {
    padding-top: 48px;
  }

  .document section {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .site-footer {
    flex-direction: column;
  }
}