:root {
  color-scheme: dark;
  font-family: "Yu Gothic UI", "Noto Sans JP", system-ui, sans-serif;
  color: #f4f7f9;
  background: #080d16;
  --panel: #111927;
  --panel-soft: #152231;
  --line: #26384a;
  --accent: #55d2b1;
  --accent-strong: #82efd2;
  --muted: #afbdc9;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 15% 0%, rgba(38, 151, 128, 0.2), transparent 32rem),
    #080d16;
  line-height: 1.8;
}

.page-shell {
  width: min(920px, calc(100% - 32px));
  margin: 0 auto;
  padding: 64px 0 80px;
}

.page-header {
  padding: 0 4px 24px;
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

h1,
h2 {
  line-height: 1.35;
}

h1 {
  margin: 0;
  font-size: clamp(2rem, 5vw, 3.25rem);
}

h2 {
  margin: 0 0 12px;
  font-size: 1.25rem;
}

.lead {
  max-width: 720px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 1.05rem;
}

.updated {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

section {
  margin-top: 24px;
  padding: 24px 28px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: linear-gradient(150deg, rgba(21, 34, 49, 0.96), rgba(17, 25, 39, 0.96));
  box-shadow: 0 16px 42px rgba(0, 0, 0, 0.18);
}

section p:last-child,
section ul:last-child,
section ol:last-child {
  margin-bottom: 0;
}

.notice {
  border-color: rgba(85, 210, 177, 0.55);
}

a {
  color: var(--accent-strong);
  text-underline-offset: 0.2em;
}

code {
  padding: 0.18em 0.42em;
  border: 1px solid #32485b;
  border-radius: 6px;
  background: #0a111d;
  color: #dffcf4;
  overflow-wrap: anywhere;
}

li + li {
  margin-top: 8px;
}

.page-nav {
  display: flex;
  gap: 16px;
  margin-top: 28px;
  padding: 20px 4px 0;
  border-top: 1px solid var(--line);
}

@media (max-width: 600px) {
  .page-shell {
    width: min(100% - 20px, 920px);
    padding: 36px 0 52px;
  }

  section {
    padding: 20px;
    border-radius: 14px;
  }
}