:root {
  --bg: #05070b;
  --text: #f5f7fb;
  --muted: #adb8c7;
  --line: rgba(255, 255, 255, .12);
  --accent: #69c9ff;
  --accent2: #8ef0c8;
  --max: 760px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(ellipse at 12% 0, rgba(105, 201, 255, .10), transparent 700px),
    linear-gradient(180deg, var(--bg), #090d14 55%, var(--bg));
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", "PingFang SC", sans-serif;
  line-height: 1.85;
}
a { color: inherit; text-decoration: none; }
.wrap { width: min(100% - 48px, var(--max)); margin-inline: auto; }

.p-progress { position: fixed; inset: auto 0 0; height: 3px; z-index: 100; pointer-events: none; }
.p-progress span { display: block; height: 100%; width: 0; background: linear-gradient(90deg, var(--accent), var(--accent2)); }
.p-nav {
  position: sticky;
  top: 14px;
  z-index: 90;
  width: min(100% - 48px, 1080px);
  margin: 14px auto 0;
  padding: 10px 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(6, 9, 14, .88);
  -webkit-backdrop-filter: blur(18px);
  backdrop-filter: blur(18px);
}
.p-home-link, .p-contents-link {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 650;
  line-height: 1.35;
}
.p-home-link > [aria-hidden] { font-size: 21px; line-height: 1; }
.p-contents-link { margin-left: auto; color: var(--muted); }
.p-nav > a { flex-shrink: 0; }
.p-home-link:hover, .p-contents-link:hover { background: rgba(255, 255, 255, .06); color: var(--text); }

.p-intro { padding-top: clamp(44px, 6vw, 76px); }
.eyebrow {
  margin: 0 0 16px;
  color: var(--muted);
  font: 600 11px/1.6 ui-monospace, SFMono-Regular, Menlo, monospace;
  letter-spacing: .12em;
}
.p-intro h1 { margin: 0; font-size: clamp(32px, 5vw, 54px); line-height: 1.2; letter-spacing: -.045em; text-wrap: balance; }
.lead { margin: 24px 0 0; color: var(--muted); font-size: 17px; }

.p-number { flex-shrink: 0; color: var(--accent); font: 500 11px/1.6 ui-monospace, SFMono-Regular, Menlo, monospace; letter-spacing: .04em; }
.p-chapter { padding: 48px 0; border-bottom: 1px solid var(--line); }
.p-chapter-label { display: flex; align-items: baseline; gap: 12px; margin-bottom: 12px; color: var(--muted); font-size: 13px; }
.p-chapter h2 { margin: 0 0 22px; font-size: clamp(25px, 3.5vw, 34px); line-height: 1.35; letter-spacing: -.035em; text-wrap: balance; }
.p-chapter p { margin: 0 0 20px; font-size: 17px; }
.p-chapter p:last-child { margin-bottom: 0; }
.p-project-link { display: inline-flex; align-items: center; min-height: 44px; padding-block: 8px; color: var(--accent); font-size: 14px; text-decoration: underline; text-underline-offset: 5px; text-decoration-color: rgba(105, 201, 255, .4); }
.p-project-link:hover { color: #b5e8ff; text-decoration-color: currentColor; }
.p-reading { overflow-wrap: break-word; }
.p-return { padding: 28px 0 40px; }
.p-return .p-home-link { padding-left: 0; }
.p-footer { padding: 24px 0 32px; display: flex; flex-wrap: wrap; justify-content: space-between; gap: 10px 20px; color: var(--muted); font-size: 12px; }

@media (max-width: 700px) {
  .wrap { width: calc(100% - 40px); }
  .p-nav { width: calc(100% - 24px); top: 10px; margin-top: 10px; padding: 8px; }
  .p-intro { padding-top: 38px; }
  .p-intro h1 { font-size: clamp(30px, 7vw, 42px); }
  .lead, .p-chapter p { font-size: 16px; line-height: 1.85; }
  .p-chapter { padding-block: 36px; }
  .p-chapter h2 { margin-bottom: 20px; }
  .p-footer { font-size: 11px; }
}

@media (max-width: 480px) {
  .p-nav .p-home-label { display: none; }
  .p-nav .p-home-link { width: 44px; padding: 0; }
  .p-contents-link { font-size: 13px; padding-inline: 8px; }
}

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

/* Chapter links live in the shared header navigation. */
.p-nav > nav { display: flex; gap: 20px; color: var(--muted); font-size: 14px; line-height: 1.5; }
.p-nav > nav a { display: inline-flex; align-items: center; min-height: 44px; white-space: nowrap; }
.p-nav > nav a:hover { color: var(--text); }
@media (min-width: 861px) and (max-width: 1100px) {
  .p-nav > nav { gap: 12px; font-size: 12px; }
}