/* Layout: ledger paper. A single reading column on a faintly ruled ground;
   red ink is reserved for the vital few (the top 20% bars, key marks). */
:root {
  --paper: #EEF1EB;
  --paper-2: #E3E8E0;
  --rule: #C7D1C5;
  --ink: #15241F;
  --ink-2: #44554E;
  --red: #A8322A;
  --red-soft: #E8CFC9;
  --cover-ink: #15241F;
  --cover-sea: #1F4A55;
  --on-dark: #EEF1EB;

  --display: "Young Serif", "Georgia", "Times New Roman", serif;
  --serif: "Source Serif 4", "Georgia", "Times New Roman", serif;
  --sans: "Public Sans", "Helvetica Neue", Arial, sans-serif;
  --mono: "IBM Plex Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --step--1: 0.85rem;
  --step-0: 1.0625rem;
  --step-1: 1.3rem;
  --step-2: 1.75rem;
  --step-3: clamp(2rem, 4.5vw, 2.75rem);
  --step-4: clamp(2.6rem, 7vw, 4.4rem);

  --measure: 66ch;
  --wide: 72rem;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #111A17; --paper-2: #18231F; --rule: #2B3A34;
    --ink: #E4EAE2; --ink-2: #A3B2AB; --red: #E0786B; --red-soft: #3B2421;
    --cover-ink: #0B1210; --cover-sea: #183A42; --on-dark: #E4EAE2;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --paper: #111A17; --paper-2: #18231F; --rule: #2B3A34;
  --ink: #E4EAE2; --ink-2: #A3B2AB; --red: #E0786B; --red-soft: #3B2421;
  --cover-ink: #0B1210; --cover-sea: #183A42; --on-dark: #E4EAE2;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font: 400 var(--step-0)/1.65 var(--sans);
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration-color: var(--red); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--red); }
:focus-visible { outline: 2px solid var(--red); outline-offset: 3px; border-radius: 2px; }
h1, h2, h3 { font-family: var(--display); font-weight: 400; line-height: 1.15; text-wrap: balance; margin: 0; }
p { margin: 0; }

.wrap {
  max-width: var(--wide);
  margin-inline: auto;
  padding-left: max(20px, env(safe-area-inset-left, 0px));
  padding-right: max(20px, env(safe-area-inset-right, 0px));
}
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 16px; background: var(--ink); color: var(--paper); padding: 8px 12px; z-index: 10; }

/* Header */
.site-head { border-bottom: 1px solid var(--rule); }
.site-head .wrap { display: flex; align-items: baseline; justify-content: space-between; gap: 12px 28px; flex-wrap: wrap; padding-block: 22px; }
.brand { font-family: var(--display); font-size: 1.45rem; text-decoration: none; letter-spacing: 0.01em; }
.brand span { color: var(--red); }
.nav { display: flex; gap: 6px 22px; flex-wrap: wrap; font-size: 0.95rem; }
.nav a { text-decoration: none; color: var(--ink-2); padding-block: 4px; border-bottom: 1px solid transparent; }
.nav a:hover, .nav a[aria-current="page"] { color: var(--ink); border-bottom-color: var(--red); }

/* Labels */
.label { font: 500 0.74rem/1.2 var(--mono); letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-2); }
.label.red { color: var(--red); }

/* Hero */
.hero { padding-block: clamp(48px, 8vw, 96px) clamp(40px, 6vw, 72px); border-bottom: 1px solid var(--rule); }
.hero .wrap { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr); gap: 48px; align-items: center; }
.hero h1 { font-size: var(--step-4); letter-spacing: -0.01em; margin-top: 18px; }
.hero h1 em { font-style: normal; color: var(--red); }
.hero .lede { font-family: var(--serif); font-size: var(--step-1); line-height: 1.5; color: var(--ink-2); margin-top: 22px; max-width: 34ch; }
.hero .actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 30px; }
.pareto { width: 100%; }
.pareto text { font-family: var(--mono); font-size: 11px; fill: var(--ink-2); }
.pareto .bar { fill: var(--rule); }
.pareto .bar.vital { fill: var(--red); }
.pareto .curve { fill: none; stroke: var(--ink); stroke-width: 1.6; }
.pareto .axis { stroke: var(--ink-2); stroke-width: 1; }
.pareto .guide { stroke: var(--ink-2); stroke-width: 1; stroke-dasharray: 3 4; }
.pareto .dot { fill: var(--red); stroke: var(--paper); stroke-width: 2; }
.pareto .callout { font-size: 12px; fill: var(--ink); font-weight: 500; }
.chart-cap { margin-top: 10px; font: 400 0.8rem/1.4 var(--mono); color: var(--ink-2); }

.btn { display: inline-flex; align-items: center; gap: 8px; font: 600 0.95rem/1 var(--sans); padding: 13px 20px; border-radius: 2px; text-decoration: none; border: 1.5px solid var(--ink); }
.btn.solid { background: var(--ink); color: var(--paper); }
.btn.solid:hover { background: var(--red); border-color: var(--red); color: var(--on-dark); }
.btn.ghost:hover { border-color: var(--red); }

/* Sections */
.section { padding-block: clamp(48px, 7vw, 88px); border-bottom: 1px solid var(--rule); }
.section-head { display: flex; justify-content: space-between; align-items: baseline; gap: 12px 24px; flex-wrap: wrap; margin-bottom: 36px; }
.section-head h2 { font-size: var(--step-3); }
.section-head a { font-size: 0.95rem; color: var(--ink-2); }

/* Book shelf */
.shelf { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 32px 28px; }
.book-card { display: grid; grid-template-rows: auto auto; gap: 18px; text-decoration: none; }
.book-card .meta { display: grid; gap: 6px; }
.book-card h3 { font-size: 1.3rem; }
.book-card p { color: var(--ink-2); font-size: 0.95rem; line-height: 1.5; }
.book-card:hover h3 { color: var(--red); }
.book-card:hover .cover { transform: translateY(-4px); }

/* Typographic covers */
.cover {
  aspect-ratio: 2 / 3; max-width: 100%; width: 100%;
  display: flex; flex-direction: column; justify-content: space-between;
  padding: 9% 9% 8%;
  border-radius: 1px 4px 4px 1px;
  box-shadow: inset 6px 0 0 rgba(0,0,0,0.14), 0 1px 0 rgba(0,0,0,0.05), 0 14px 26px -18px rgba(0,0,0,0.55);
  transition: transform .25s ease;
  overflow: hidden; position: relative;
}
.cover img { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.cover .c-series { font: 500 0.6rem/1.3 var(--mono); letter-spacing: 0.14em; text-transform: uppercase; opacity: .8; }
.cover .c-title { font-family: var(--display); font-size: clamp(1.15rem, 2.3vw, 1.55rem); line-height: 1.08; }
.cover .c-sub { font-family: var(--serif); font-size: 0.78rem; line-height: 1.35; margin-top: 10px; opacity: .85; }
.cover .c-author { font: 600 0.68rem/1 var(--sans); letter-spacing: 0.2em; text-transform: uppercase; }
.cover .c-mark { height: 3px; width: 34%; background: currentColor; opacity: .9; margin-bottom: 12px; }
.cover.tone-ink { background: var(--cover-ink); color: #EEF1EB; }
.cover.tone-ink .c-mark { background: #D7564A; }
.cover.tone-red { background: #9C2E27; color: #F6EDE9; }
.cover.tone-sea { background: var(--cover-sea); color: #E9F0EE; }
.cover.tone-sea .c-mark { background: #E6B65A; }
.cover.tone-paper { background: #F7F6F1; color: #15241F; box-shadow: inset 6px 0 0 rgba(0,0,0,0.08), 0 0 0 1px var(--rule), 0 14px 26px -18px rgba(0,0,0,0.5); }
.cover.tone-paper .c-mark { background: #A8322A; }

/* Principles strip */
.principles { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); border-top: 1px solid var(--rule); }
.principle { padding: 26px 24px 28px 0; border-bottom: 1px solid var(--rule); display: grid; gap: 8px; align-content: start; }
.principle:not(:nth-child(3n+1)) { padding-left: 24px; border-left: 1px solid var(--rule); }
.principle h3 { font-size: 1.35rem; }
.principle p { color: var(--ink-2); font-family: var(--serif); font-size: 1rem; line-height: 1.55; }

/* The 80/20 loop: a real sequence, so it is an ordered list */
.loop { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-top: 2px solid var(--ink); counter-reset: step; }
.loop li { counter-increment: step; padding: 22px 22px 26px 0; display: grid; gap: 8px; align-content: start; position: relative; }
.loop li + li { padding-left: 22px; border-left: 1px solid var(--rule); }
.loop li::before { content: counter(step); font: 400 2.4rem/1 var(--display); color: var(--rule); }
.loop h3 { font-size: 1.35rem; }
.loop p { color: var(--ink-2); font-family: var(--serif); line-height: 1.55; }
.loop-note { margin-top: 18px; font-family: var(--serif); font-style: italic; color: var(--ink-2); }

/* Post lists */
.post-list { display: grid; }
.post-item { display: grid; grid-template-columns: 9rem minmax(0, 1fr); gap: 8px 32px; padding-block: 26px; border-top: 1px solid var(--rule); text-decoration: none; }
.post-item:last-child { border-bottom: 1px solid var(--rule); }
.post-item { grid-template-columns: 11rem minmax(0, 1fr); }
.post-meta { display: grid; gap: 4px; align-content: start; }
.post-meta .label { font-size: 0.66rem; line-height: 1.4; }
.post-item time { font: 400 0.82rem/1.9 var(--mono); color: var(--ink-2); font-variant-numeric: tabular-nums; }
.post-item h3 { font-size: var(--step-1); }
.post-item p { color: var(--ink-2); margin-top: 8px; font-family: var(--serif); max-width: var(--measure); }
.post-item:hover h3 { color: var(--red); }

/* Quote band */
.quote { padding-block: clamp(56px, 8vw, 100px); border-bottom: 1px solid var(--rule); background: var(--paper-2); }
.quote blockquote { margin: 0; max-width: 52rem; }
.quote blockquote p { font-family: var(--display); font-size: var(--step-3); line-height: 1.22; text-wrap: balance; }
.quote cite { display: block; margin-top: 20px; font-style: normal; }

/* Page heads */
.page-head { padding-block: clamp(44px, 7vw, 80px) 36px; border-bottom: 1px solid var(--rule); }
.page-head h1 { font-size: var(--step-4); margin-top: 14px; }
.page-head .lede { font-family: var(--serif); font-size: var(--step-1); color: var(--ink-2); margin-top: 18px; max-width: 44ch; line-height: 1.5; }

/* Book detail */
.book-detail { display: grid; grid-template-columns: minmax(0, 18rem) minmax(0, 1fr); gap: 56px; padding-block: 56px; align-items: start; }
.book-detail .cover { position: sticky; top: calc(24px + env(safe-area-inset-top, 0px)); }
.book-detail .c-title { font-size: 1.7rem; }
.book-facts { display: grid; grid-template-columns: auto minmax(0, 1fr); gap: 6px 20px; margin-top: 28px; font-size: 0.9rem; }
.book-facts dt { font: 500 0.72rem/1.9 var(--mono); letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-2); }
.book-facts dd { margin: 0; font-variant-numeric: tabular-nums; }
.hook { font-family: var(--display); font-size: var(--step-2); line-height: 1.25; color: var(--red); }
.prose { font-family: var(--serif); font-size: 1.15rem; line-height: 1.7; max-width: var(--measure); display: grid; gap: 1.1em; }
.prose h2 { font-size: var(--step-2); margin-top: 0.8em; }
.prose h3 { font-size: var(--step-1); margin-top: 0.6em; }
.prose blockquote { margin: 0.4em 0; padding-left: 20px; border-left: 3px solid var(--red); color: var(--ink-2); font-style: italic; }
.prose ul, .prose ol { margin: 0; padding-left: 1.3em; display: grid; gap: 0.4em; }
.prose hr { border: 0; border-top: 1px solid var(--rule); width: 100%; }
.prose code { font-family: var(--mono); font-size: 0.85em; background: var(--paper-2); padding: 1px 5px; border-radius: 2px; }
.contents-table { width: 100%; border-collapse: collapse; margin-top: 8px; font-size: 0.98rem; }
.contents-table th, .contents-table td { text-align: left; vertical-align: top; padding: 14px 16px 14px 0; border-top: 1px solid var(--rule); }
.contents-table th { font-family: var(--display); font-weight: 400; width: 38%; font-size: 1.05rem; }
.contents-table td { color: var(--ink-2); }
.table-scroll { overflow-x: auto; }
.stack { display: grid; gap: 28px; }

/* Article */
.article-head { padding-block: clamp(44px, 7vw, 80px) 32px; }
.article-head h1 { font-size: var(--step-4); margin-top: 16px; max-width: 18ch; }
.article-head .dek { font-family: var(--serif); font-size: var(--step-1); color: var(--ink-2); margin-top: 20px; max-width: 46ch; line-height: 1.5; }
.byline { display: flex; gap: 8px 18px; flex-wrap: wrap; margin-top: 26px; font: 400 0.85rem/1.4 var(--mono); color: var(--ink-2); }
.article-body { padding-block: 8px 64px; border-bottom: 1px solid var(--rule); }
.article-body .prose > p:first-of-type::first-letter { font-family: var(--display); float: left; font-size: 3.6em; line-height: 0.85; padding: 6px 10px 0 0; color: var(--red); }
.from-book { display: grid; grid-template-columns: 5.5rem minmax(0, 1fr); gap: 20px; align-items: center; margin-top: 48px; padding: 20px; border: 1px solid var(--rule); max-width: var(--measure); text-decoration: none; }
.from-book .cover { padding: 10%; }
.from-book .cover .c-title { font-size: 0.62rem; }
.from-book .cover .c-sub, .from-book .cover .c-series, .from-book .cover .c-author { display: none; }
.from-book h3 { font-size: 1.2rem; margin-top: 4px; }
.from-book:hover h3 { color: var(--red); }

/* About */
.two-col { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 20rem); gap: 56px; padding-block: 56px; align-items: start; }
.facts { display: grid; gap: 0; border-top: 1px solid var(--rule); }
.facts div { padding-block: 16px; border-bottom: 1px solid var(--rule); display: grid; gap: 4px; }
.facts strong { font-family: var(--display); font-weight: 400; font-size: 1.15rem; }
.facts span { color: var(--ink-2); font-size: 0.95rem; }

/* Footer */
.site-foot { padding-block: 40px 56px; font-size: 0.9rem; color: var(--ink-2); }
.site-foot .wrap { display: flex; justify-content: space-between; gap: 16px 32px; flex-wrap: wrap; }
.site-foot nav { display: flex; gap: 8px 20px; flex-wrap: wrap; }
.site-foot a { text-decoration: none; }
.site-foot a:hover { color: var(--red); }

/* 404 */
.notfound { padding-block: 96px; }
.notfound h1 { font-size: var(--step-4); margin-top: 14px; }
.notfound p { margin-top: 18px; font-family: var(--serif); font-size: var(--step-1); color: var(--ink-2); }

@media (max-width: 960px) {
  .shelf { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .loop { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .loop li:nth-child(3) { padding-left: 0; border-left: 0; }
  .loop li:nth-child(n+3) { border-top: 1px solid var(--rule); }
  .hero .wrap { grid-template-columns: minmax(0, 1fr); }
  .hero .lede { max-width: 44ch; }
}
@media (max-width: 760px) {
  .principles { grid-template-columns: minmax(0, 1fr); }
  .principle, .principle:not(:nth-child(3n+1)) { padding: 22px 0; border-left: 0; }
  .book-detail, .two-col { grid-template-columns: minmax(0, 1fr); gap: 36px; }
  .book-detail .cover { position: static; max-width: 15rem; }
  .post-item { grid-template-columns: minmax(0, 1fr); }
  .post-meta { grid-auto-flow: column; justify-content: start; gap: 14px; align-items: baseline; }
  .loop { grid-template-columns: minmax(0, 1fr); }
  .loop li, .loop li + li { padding: 20px 0; border-left: 0; border-top: 1px solid var(--rule); }
  .loop li:first-child { border-top: 0; }
}
@media (max-width: 440px) {
  .shelf { gap: 28px 16px; }
  .cover .c-sub { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  * { transition: none !important; }
}