/* ============================================================
   productwiki.online — design tokens + all layout rules
   Tokens defined once here, referenced across the site.
   No hard-coded hex colors appear outside this :root block.
   ============================================================ */

:root {
  --ink: #1a1a1a;
  --muted: #8a8a8a;
  --hairline: #e5e3dc;
  --bg: #fafaf7;
  --tint: #f2efe4;
  --measure: 34rem;
  --rail: 15rem;
  --gutter: clamp(1.5rem, 5vw, 4rem);
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

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

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--ink);
}

body {
  font-family: Charter, "Source Serif Pro", "Iowan Old Style", Georgia, "Times New Roman", serif;
  font-size: 1.0625rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.sans {
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

/* ============ Skip link ============ */

.skip-link {
  position: absolute;
  left: 0;
  top: 0;
  padding: 0.75rem 1rem;
  background: var(--ink);
  color: var(--bg);
  text-decoration: none;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  transform: translateY(-120%);
  z-index: 200;
}

.skip-link:focus {
  transform: translateY(0);
  outline: 2px solid var(--ink);
  outline-offset: -2px;
}

/* ============ Shell + rail ============ */

.shell,
.landing-shell {
  display: grid;
  grid-template-columns: var(--rail) minmax(0, 1fr);
  gap: 0;
  min-height: 100vh;
}

.rail {
  position: sticky;
  top: 0;
  align-self: start;
  height: 100vh;
  padding: 3rem 1.5rem 2rem 2rem;
  border-right: 1px solid var(--hairline);
  overflow-y: auto;
}

.rail-eyebrow {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.75rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.25rem 0;
}

.rail-title {
  font-family: Charter, Georgia, serif;
  font-size: 1rem;
  line-height: 1.3;
  margin: 0 0 2rem 0;
  color: var(--ink);
  font-weight: 400;
}

.rail-title a {
  color: inherit;
  text-decoration: none;
}

.rail-title a:hover { text-decoration: underline; text-underline-offset: 3px; }
.rail-title a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

.rail ol {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: chapter;
}

.rail li {
  counter-increment: chapter;
  margin: 0 0 0.875rem 0;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  line-height: 1.35;
}

.rail li a {
  display: block;
  color: var(--muted);
  text-decoration: none;
  position: relative;
  border-left: 2px solid transparent;
  padding: 0.125rem 0 0.125rem 1.75rem;
  margin-left: -0.5rem;
}

.rail li a::before {
  content: counter(chapter, decimal-leading-zero);
  position: absolute;
  left: 0.25rem;
  top: 0.125rem;
  font-variant-numeric: tabular-nums;
  font-size: 0.75rem;
  color: var(--muted);
  letter-spacing: 0.05em;
}

.rail li a[href]:hover { color: var(--ink); }
.rail li a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
.rail li.current a { color: var(--ink); border-left-color: var(--ink); }

.rail li.pending a {
  color: var(--muted);
  cursor: default;
}

.rail li.pending a::after {
  content: "— soon";
  font-size: 0.75rem;
  color: var(--muted);
  margin-left: 0.5rem;
  letter-spacing: 0.02em;
}

.rail li.unnumbered { counter-increment: none; }
.rail li.unnumbered a::before { content: ""; }

.rail-closing {
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--hairline);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
}

.rail-closing a {
  color: var(--muted);
  text-decoration: none;
  padding-left: 1.75rem;
  display: block;
  border-left: 2px solid transparent;
  margin-left: -0.5rem;
  padding: 0.125rem 0 0.125rem 1.75rem;
}

.rail-closing a:hover { color: var(--ink); }
.rail-closing a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
.rail-closing.active a { color: var(--ink); border-left-color: var(--ink); }

/* ============ Main columns ============ */

main.book,
main.landing-main {
  padding: 4rem var(--gutter) 6rem;
  max-width: calc(var(--measure) + var(--gutter) * 2);
}

/* ============ Mobile top-bar (native <details>, zero JS) ============ */

.topbar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg);
  border-bottom: 1px solid var(--hairline);
}

.topbar summary {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.875rem 1.5rem;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  cursor: pointer;
  list-style: none;
  color: var(--ink);
}

.topbar summary::-webkit-details-marker { display: none; }

.topbar summary::after {
  content: "Chapters ↓";
  color: var(--muted);
  font-size: 0.8125rem;
}

.topbar[open] summary::after { content: "Chapters ↑"; }

.topbar summary:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: -2px;
}

.topbar .drawer {
  padding: 0 1.5rem 1.5rem;
  border-top: 1px solid var(--hairline);
}

.topbar .drawer ol {
  list-style: none;
  padding: 0;
  margin: 1rem 0;
}

.topbar .drawer li a {
  display: block;
  padding: 0.5rem 0;
  color: var(--ink);
  text-decoration: none;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
}

.topbar .drawer li a.pending { color: var(--muted); }
.topbar .drawer li a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }
.topbar .drawer li.divider {
  border-top: 1px solid var(--hairline);
  margin-top: 0.5rem;
  padding-top: 0.25rem;
}

/* ============ Editorial type ============ */

h1.hero {
  font-family: Charter, Georgia, serif;
  font-weight: 400;
  font-size: clamp(2.25rem, 5.5vw, 3.5rem);
  line-height: 1.08;
  letter-spacing: -0.015em;
  margin: 0 0 2rem 0;
  max-width: 28rem;
}

.eyebrow {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.5rem 0;
}

h1.chapter-title {
  font-family: Charter, Georgia, serif;
  font-weight: 400;
  font-size: clamp(2rem, 4.5vw, 2.75rem);
  line-height: 1.12;
  letter-spacing: -0.015em;
  margin: 0 0 1.5rem 0;
}

.deck {
  font-family: Charter, Georgia, serif;
  font-size: clamp(1.1875rem, 2vw, 1.375rem);
  line-height: 1.45;
  color: var(--muted);
  max-width: var(--measure);
  margin: 0 0 3rem 0;
  padding: 0 0 2rem 0;
  border-bottom: 1px solid var(--hairline);
}

main.book article > p,
main.book article > ul,
main.book article > ol {
  max-width: var(--measure);
  margin: 0 0 1.5rem 0;
}

main.book article h2 {
  font-family: Charter, Georgia, serif;
  font-weight: 400;
  font-size: 1.5rem;
  line-height: 1.25;
  letter-spacing: -0.005em;
  margin: 3.5rem 0 1.25rem 0;
  max-width: var(--measure);
}

main.book article h3 {
  font-family: Charter, Georgia, serif;
  font-weight: 600;
  font-size: 1.15rem;
  line-height: 1.35;
  margin: 2rem 0 0.75rem 0;
}

main.book a {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

main.book a:hover { text-decoration-thickness: 2px; }

main.book a:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
  text-decoration: none;
}

main.book article aside.note {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  line-height: 1.55;
  color: var(--muted);
  max-width: var(--measure);
  padding: 1rem 0 1rem 1.25rem;
  border-left: 2px solid var(--hairline);
  margin: 2rem 0;
}

main.book hr.sep,
main.book article hr {
  border: 0;
  border-top: 1px solid var(--hairline);
  margin: 3rem 0;
  max-width: var(--measure);
}

/* Deep-link tint on arrived-at headings and footnotes (no animation) */

main.book article h2:target,
main.book article h3:target {
  background: var(--tint);
  padding: 0.25rem 0.5rem;
  margin-left: -0.5rem;
  border-radius: 2px;
}

/* Footnotes */

.fn-ref {
  font-size: 0.75rem;
  vertical-align: super;
  line-height: 0;
  padding: 0 0.15em;
  text-decoration: none;
}

section.footnotes {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--hairline);
  max-width: var(--measure);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  color: var(--muted);
}

section.footnotes ol { padding-left: 1.25rem; margin: 0; }
section.footnotes li { margin: 0 0 0.75rem 0; }
section.footnotes li:target {
  background: var(--tint);
  padding: 0.25rem 0.5rem;
  margin-left: -0.5rem;
}

/* ============ Landing ============ */

.landing-shell .rail { padding-top: 3rem; }

.thesis {
  font-family: Charter, Georgia, serif;
  font-size: clamp(1.25rem, 2vw, 1.5rem);
  line-height: 1.4;
  color: var(--ink);
  max-width: 30rem;
  margin: 0 0 3rem 0;
  padding: 1.5rem 0;
  border-top: 1px solid var(--hairline);
  border-bottom: 1px solid var(--hairline);
}

.chapters-h {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.8125rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 1.5rem 0;
}

.chapter-list {
  list-style: none;
  padding: 0;
  margin: 0;
  counter-reset: cl;
  max-width: var(--measure);
}

.chapter-list li {
  counter-increment: cl;
  padding: 1.25rem 0;
  border-top: 1px solid var(--hairline);
  display: grid;
  grid-template-columns: 3rem 1fr;
  align-items: baseline;
  gap: 1rem;
}

.chapter-list li:last-child { border-bottom: 1px solid var(--hairline); }

.chapter-list li::before {
  content: counter(cl, decimal-leading-zero);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-variant-numeric: tabular-nums;
  font-size: 0.875rem;
  color: var(--muted);
  letter-spacing: 0.05em;
}

.chapter-list li.unnumbered { counter-increment: none; }
.chapter-list li.unnumbered::before { content: ""; }

.chapter-list a {
  font-family: Charter, Georgia, serif;
  font-size: 1.25rem;
  line-height: 1.3;
  color: var(--ink);
  text-decoration: none;
  display: block;
}

.chapter-list a[href]:hover {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.chapter-list a:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

.chapter-list .cd {
  display: block;
  font-family: Charter, Georgia, serif;
  font-size: 0.9375rem;
  color: var(--muted);
  margin-top: 0.25rem;
}

.chapter-list li.pending a {
  color: var(--muted);
  cursor: default;
  pointer-events: none;
}

.chapter-list li.pending a::after {
  content: " — soon";
  font-size: 0.875rem;
  color: var(--muted);
  font-family: ui-sans-serif, system-ui, sans-serif;
  letter-spacing: 0.02em;
}

.start-here {
  display: inline-block;
  margin-top: 3rem;
  padding: 0.875rem 0;
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--ink);
  letter-spacing: 0.01em;
}

.start-here:hover {
  padding-bottom: 0.75rem;
  border-bottom-width: 2px;
}

.start-here:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 4px;
}

.start-here::after { content: " →"; }

/* ============ Pager (chapter prev/next) ============ */

.pager {
  display: flex;
  justify-content: space-between;
  max-width: var(--measure);
  margin: 4rem 0 0;
  padding: 2rem 0 0;
  border-top: 1px solid var(--hairline);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
}

.pager a {
  color: var(--ink);
  text-decoration: none;
  display: block;
}

.pager a small {
  display: block;
  font-size: 0.75rem;
  color: var(--muted);
  letter-spacing: 0.05em;
  text-transform: uppercase;
  margin-bottom: 0.25rem;
}

.pager a:hover .pager-t {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.pager .prev { text-align: left; }
.pager .next { text-align: right; }

/* ============ Pending chapter shell ============ */

.pending-page { max-width: 30rem; }

.pending-page h1 {
  font-family: Charter, Georgia, serif;
  font-weight: 400;
  font-size: clamp(2rem, 4.5vw, 2.75rem);
  line-height: 1.12;
  color: var(--muted);
  margin: 0 0 1.5rem 0;
}

.pending-page p {
  color: var(--muted);
  max-width: 28rem;
  margin-bottom: 1.5rem;
}

.pending-page a.back {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--ink);
}

.pending-page a.back:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

/* ============ 404 ============ */

.fourofour { max-width: 30rem; }

.fourofour h1 {
  font-family: Charter, Georgia, serif;
  font-weight: 400;
  font-size: clamp(2.5rem, 6vw, 3.75rem);
  line-height: 1.1;
  margin: 0 0 1.5rem 0;
}

.fourofour p {
  color: var(--muted);
  margin-bottom: 1.5rem;
  max-width: 28rem;
}

.fourofour a {
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.9375rem;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--ink);
}

.fourofour a:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
}

/* ============ Footer ============ */

footer.site {
  padding: 3rem 0 2rem;
  margin-top: 6rem;
  border-top: 1px solid var(--hairline);
  font-family: ui-sans-serif, system-ui, sans-serif;
  font-size: 0.8125rem;
  color: var(--muted);
  letter-spacing: 0.02em;
  max-width: var(--measure);
}

footer.site a {
  color: var(--muted);
  text-decoration: underline;
  text-underline-offset: 3px;
}

footer.site a:hover { color: var(--ink); }
footer.site a:focus-visible { outline: 2px solid var(--ink); outline-offset: 2px; }

/* ============ Responsive ============ */

@media (max-width: 900px) {
  .shell, .landing-shell {
    grid-template-columns: 1fr;
  }
  .rail { display: none; }
  .topbar { display: block; }
  main.book, main.landing-main {
    padding: 2.5rem 1.5rem 4rem;
  }
  footer.site {
    padding: 2rem 0;
    margin-top: 4rem;
  }
}

@media (max-width: 480px) {
  h1.hero { font-size: 2rem; }
  .deck { font-size: 1.0625rem; }
  body { font-size: 1.0625rem; line-height: 1.6; }
  .chapter-list a { font-size: 1.0625rem; }
  .thesis { font-size: 1.125rem; }
}

/* Global focus fallback — ensure every interactive element gets an ink ring */

:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 2px;
}