/* Pithy Books: reading-first, mobile-first.
   Surfaces: 0 = page, 1 = raised (cards/header), inset = wells/inputs.
   Accent tint is reserved for the takeaways checkpoint only. */
:root {
  --bg: #faf9f7;
  --bg-elev: #ffffff;
  --surface-0: #faf9f7;
  --surface-1: #ffffff;
  --surface-inset: #f1efeB;
  --text: #1a1d21;
  --muted: #5c6570;
  --border: #e4e1db;
  --border-strong: #d3cfc6;
  --accent: #1f6f54;
  --accent-strong: #175a43;
  --accent-soft: #e6f2ed;
  --danger: #9b2c2c;
  --shadow: 0 1px 2px rgba(16, 20, 24, 0.07);
  --shadow-pop: 0 4px 16px rgba(16, 20, 24, 0.12), 0 1px 2px rgba(16, 20, 24, 0.08);
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius: 8px;
  --wrap: 72rem;
  --prose: 44rem;
  --font: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-serif: Georgia, "Times New Roman", serif;
  /* Type scale (deliberate): xs / sm / base / lg / xl / 2xl / 3xl */
  --fs-xs: 0.8125rem;
  --fs-sm: 0.875rem;
  --fs-base: 1.0625rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  /* Spacing (4pt base) */
  --s1: 0.25rem;
  --s2: 0.5rem;
  --s3: 0.75rem;
  --s4: 1rem;
  --s6: 1.5rem;
  --s8: 2rem;
  --s12: 3rem;
  /* Motion: purposeful only, transform + opacity */
  --ease-out: cubic-bezier(0.23, 1, 0.32, 1);
  --ease-in-out: cubic-bezier(0.77, 0, 0.175, 1);
  --dur-press: 140ms;
  --dur-pop: 180ms;
  color-scheme: light;
}

:root[data-theme="dark"] {
  --bg: #121518;
  --bg-elev: #1a1e23;
  --surface-0: #121518;
  --surface-1: #1a1e23;
  --surface-inset: #20262e;
  --text: #e8eaed;
  --muted: #9aa3ad;
  --border: #2a3038;
  --border-strong: #39414c;
  --accent: #4ecf9f;
  --accent-strong: #6bdbb1;
  --accent-soft: #16322a;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-pop: 0 4px 16px rgba(0, 0, 0, 0.4);
  color-scheme: dark;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #121518;
    --bg-elev: #1a1e23;
    --surface-0: #121518;
    --surface-1: #1a1e23;
    --surface-inset: #20262e;
    --text: #e8eaed;
    --muted: #9aa3ad;
    --border: #2a3038;
    --border-strong: #39414c;
    --accent: #4ecf9f;
    --accent-strong: #6bdbb1;
    --accent-soft: #16322a;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
    --shadow-pop: 0 4px 16px rgba(0, 0, 0, 0.4);
    color-scheme: dark;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: var(--fs-base);
  line-height: 1.65;
  color: var(--text);
  background: var(--surface-0);
  text-rendering: optimizeLegibility;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

a:hover {
  color: var(--accent-strong);
}

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

.wrap {
  width: min(100% - 2rem, var(--wrap));
  margin-inline: auto;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: 0.5rem;
  background: var(--accent);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  z-index: 100;
  transform: translateY(-250%);
  transition: transform 150ms var(--ease-out);
}

.skip-link:focus {
  transform: translateY(0);
}

/* Header — solid surface, no blur. Border carries hierarchy on scroll. */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--surface-0);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  min-height: 3.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--text);
  font-weight: 700;
  font-size: 1.05rem;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 1.75rem;
  height: 1.75rem;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  margin-left: auto;
}

.site-nav a {
  text-decoration: none;
  color: var(--text);
  padding: 0.6rem 0.8rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  min-height: 2.75rem;
  display: inline-flex;
  align-items: center;
  transition: background-color var(--dur-press) var(--ease-out), color var(--dur-press) var(--ease-out);
}

.site-nav a[aria-current="page"] {
  background: var(--surface-inset);
  color: var(--text);
  font-weight: 700;
  box-shadow: inset 0 -2px 0 var(--accent);
}

.nav-search {
  font-weight: 600;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  min-width: 2.75rem;
  height: 2.75rem;
  padding: 0 0.55rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  cursor: pointer;
  flex-shrink: 0;
  transition: transform var(--dur-press) var(--ease-out), border-color var(--dur-press) var(--ease-out), background-color var(--dur-press) var(--ease-out);
}

.theme-toggle:active {
  transform: scale(0.97);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  margin-left: 0.5rem;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 2.75rem;
  height: 2.75rem;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  cursor: pointer;
  transition: transform var(--dur-press) var(--ease-out), border-color var(--dur-press) var(--ease-out);
}

.nav-toggle:active {
  transform: scale(0.97);
}

.nav-toggle span {
  display: block;
  width: 1.1rem;
  height: 2px;
  margin-inline: auto;
  background: var(--text);
  border-radius: 1px;
}

@media (max-width: 720px) {
  .nav-toggle {
    display: flex;
  }

  .header-actions {
    margin-left: auto;
  }

  .site-nav {
    display: none;
    position: absolute;
    left: 0;
    right: 0;
    top: 100%;
    flex-direction: column;
    align-items: stretch;
    padding: 0.5rem 1rem 1rem;
    background: var(--surface-1);
    border-bottom: 1px solid var(--border);
    opacity: 0;
    transform: translateY(-8px) scale(0.98);
    transform-origin: top center;
    transition: opacity var(--dur-pop) var(--ease-out), transform var(--dur-pop) var(--ease-out), display var(--dur-pop) allow-discrete;
  }

  .site-nav.open {
    display: flex;
    opacity: 1;
    transform: none;
    @starting-style {
      opacity: 0;
      transform: translateY(-8px) scale(0.98);
    }
  }

  .site-nav a {
    padding: 0.75rem;
  }
}

/* Hero — flat, single-column reading entry. Search is primary. */
.hero {
  padding: var(--s12) 0 var(--s8);
  background: var(--surface-0);
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  max-width: var(--prose);
}

.eyebrow {
  margin: 0 0 var(--s2);
  font-size: var(--fs-xs);
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
}

.hero h1 {
  margin: 0 0 var(--s3);
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

.lede {
  margin: 0 0 var(--s6);
  color: var(--muted);
  font-size: 1.1rem;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s2);
  margin-bottom: var(--s4);
}

/* Buttons — one model: secondary outline, primary fill, quiet text.
   Press feedback only; hover gated below for fine pointers. */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  min-height: 2.75rem;
  padding: 0.65rem 1.1rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--surface-1);
  color: var(--text);
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--dur-press) var(--ease-out), border-color var(--dur-press) var(--ease-out), background-color var(--dur-press) var(--ease-out), color var(--dur-press) var(--ease-out);
}

.btn:active {
  transform: scale(0.97);
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.btn-primary:active {
  transform: scale(0.97);
}

.hero-search,
.search-form {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  position: relative;
}

.hero-search input,
.search-form input {
  flex: 1 1 16rem;
  min-width: 0;
  min-height: 2.75rem;
  padding: 0.7rem 0.9rem;
  font: inherit;
  font-size: 1rem;
  color: var(--text);
  background: var(--surface-1);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
}

.hero-search input:focus,
.search-form input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
  border-color: transparent;
}

/* Sections */
.section {
  padding: 2.25rem 0;
}

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.25rem;
}

.section-head h2 {
  margin: 0;
  font-size: 1.35rem;
  letter-spacing: -0.01em;
}

.section-head a {
  font-size: 0.95rem;
  font-weight: 600;
  text-decoration: none;
}

.split {
  display: grid;
  gap: 2rem;
}

@media (min-width: 800px) {
  .split {
    grid-template-columns: 1fr 1fr;
  }
}

.page-head {
  padding: 2rem 0 0.5rem;
}

.page-head h1 {
  margin: 0 0 0.5rem;
  font-size: clamp(1.5rem, 3vw, 2rem);
  letter-spacing: -0.02em;
}

.muted {
  color: var(--muted);
}

/* Book cards — flat bordered rows. No lift: hover changes border only.
   Covers at natural size (never upscaled). */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(100%, 19rem), 1fr));
  gap: var(--s4);
}

.book-card {
  display: flex;
  flex-direction: row;
  align-items: stretch;
  gap: var(--s3);
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  padding: var(--s3);
  transition: border-color var(--dur-press) var(--ease-out);
}

.book-card-cover {
  display: flex;
  align-items: center;
  justify-content: center;
  flex: 0 0 96px;
  width: 96px;
  aspect-ratio: 2 / 3;
  min-height: 0;
  align-self: flex-start;
  background: var(--surface-inset);
  border: 1px solid var(--border);
  overflow: hidden;
  border-radius: var(--radius-sm);
}

.book-card-cover img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  background: var(--surface-1);
  image-rendering: auto;
}

.cover-fallback {
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
  min-height: 135px;
  background: var(--surface-inset);
  color: var(--muted);
  font-size: 1.5rem;
  font-weight: 800;
}

.cover-fallback.small {
  min-height: 135px;
  width: 90px;
  font-size: 1.2rem;
  border-radius: var(--radius-sm);
}

.cover-fallback.big {
  min-height: 135px;
  width: 90px;
  font-size: 1.5rem;
  border-radius: var(--radius-md);
}

.book-card-body {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
  padding: 0;
  flex: 1;
  min-width: 0;
}

.book-card-badges:empty {
  display: none;
}

.book-card-title {
  margin: 0;
  font-size: 1.05rem;
  line-height: 1.35;
}

.book-card-title a {
  color: var(--text);
  text-decoration: none;
}

.book-card-title a:hover {
  color: var(--accent);
}

.book-card-meta {
  margin: 0;
  font-size: 0.9rem;
  color: var(--muted);
}

.book-card-excerpt {
  margin: 0.25rem 0 0;
  font-size: 0.9rem;
  color: var(--muted);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.book-card-stats {
  margin: auto 0 0;
  padding-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--muted);
  border-top: 1px dashed var(--border);
}

/* Badges & tags */
.badge-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 0.75rem;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-sm);
  background: var(--surface-inset);
  color: var(--text);
  border: 1px solid var(--border);
  font-size: var(--fs-xs);
  font-weight: 600;
  text-decoration: none;
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

a.badge:active {
  transform: scale(0.95);
}

.badge-series {
  background: var(--surface-1);
  border-color: var(--border-strong);
  color: var(--text);
}

.badge-new {
  background: #fef3c7;
  color: #92400e;
  border-color: #f5d67b;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-size: 0.72rem;
}

:root[data-theme="dark"] .badge-new {
  background: #3a2c10;
  color: #f5d67b;
  border-color: #6b5416;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .badge-new {
    background: #3a2c10;
    color: #f5d67b;
    border-color: #6b5416;
  }
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  min-height: 2.5rem;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

.tag:active {
  transform: scale(0.97);
}

/* hidden must beat .tag's inline-flex (author styles override UA [hidden]) */
.tag[hidden] {
  display: none;
}

.tag .count {
  font-size: 0.78rem;
  color: var(--muted);
}

.plain-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.plain-list li {
  padding: 0.4rem 0;
  border-bottom: 1px dashed var(--border);
}

.plain-list a {
  text-decoration: none;
  font-weight: 600;
}

.plain-list.big li {
  padding: 0.65rem 0;
}

/* Breadcrumbs */
.breadcrumbs {
  background: var(--surface-0);
  border-bottom: 1px solid var(--border);
  font-size: var(--fs-sm);
}

.breadcrumbs .wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  padding: 0.65rem 0;
  align-items: center;
}

.breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--accent);
}

.breadcrumbs .sep {
  color: var(--border);
}

.breadcrumbs [aria-current] {
  color: var(--text);
  font-weight: 600;
}

/* Book page */
.book-page {
  padding-bottom: 3rem;
}

.book-hero {
  display: grid;
  gap: 1.5rem;
  padding: 2rem 0 1.5rem;
}

@media (min-width: 720px) {
  .book-hero {
    grid-template-columns: minmax(90px, max-content) 1fr;
    gap: 2rem;
  }
}

.book-hero-cover {
  width: 100%;
  max-width: 200px;
}

.book-hero-cover img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 2 / 3;
  object-fit: cover;
  object-position: center;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface-1);
}

.book-hero-info h1 {
  margin: 0 0 0.4rem;
  font-size: clamp(1.6rem, 3.5vw, 2rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  text-wrap: balance;
}

.byline {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
  color: var(--muted);
}

.byline a {
  font-weight: 600;
}

.book-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
  margin: 0 0 1rem;
  font-size: 0.9rem;
  color: var(--muted);
}

.book-stats span + span::before {
  content: "·";
  margin-right: 0.75rem;
  color: var(--muted);
}

/* Facts — divider rows, not mini-cards. Scans as metadata. */
.fact-table {
  display: grid;
  margin: var(--s4) 0 0;
  border-top: 1px solid var(--border);
}

.fact-table > div {
  display: grid;
  grid-template-columns: 9rem 1fr;
  gap: var(--s2);
  padding: var(--s2) 0;
  border-bottom: 1px solid var(--border);
  background: none;
  border-left: none;
  border-right: none;
  border-top: none;
  border-radius: 0;
}

.fact-table dt {
  font-size: var(--fs-xs);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  font-weight: 700;
}

.fact-table dd {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 600;
  word-break: break-word;
}

/* First-class narrow layout: stack label above value, no squeeze. */
@media (max-width: 420px) {
  .fact-table > div {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }
}

/* Series — neutral inset, accent reserved for takeaways. */
.series-box {
  margin: var(--s4) 0 var(--s6);
  padding: var(--s4);
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-left: 3px solid var(--border-strong);
  border-radius: var(--radius-sm);
}

.series-box h2 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
}

.series-list {
  margin: 0;
  padding-left: 1.2rem;
}

.series-list li {
  padding: 0.2rem 0;
}

.series-list [aria-current="true"] {
  font-weight: 700;
}

/* TOC — mobile-first checkpoint above the read, not a floated sidebar.
   Avoids narrow text wrap on mid widths; no shadow. */
.toc {
  width: 100%;
  margin: 0 0 var(--s6);
  padding: var(--s3) var(--s4);
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  display: flex;
  flex-direction: column;
}

.toc summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 0.9rem;
  line-height: 1.3;
  flex-shrink: 0;
}

.toc[open] summary {
  margin-bottom: 0.35rem;
  padding-bottom: 0.35rem;
  border-bottom: 1px solid var(--border);
}

.toc ol {
  margin: 0;
  padding-left: 1.15rem;
  font-size: 0.88rem;
  line-height: 1.4;
  min-height: 0;
}

.toc li {
  padding: 0.12rem 0;
}

.toc-l3 {
  margin-left: 0.7rem;
  list-style-type: circle;
}

.toc-l4 {
  margin-left: 1.2rem;
  list-style-type: square;
}

.toc a {
  text-decoration: none;
  font-size: 0.88rem;
}

.toc a:hover {
  text-decoration: underline;
}

.toc a.is-active {
  color: var(--accent-strong);
  font-weight: 700;
}

/* Key takeaways — the single tinted checkpoint. Accent tint lives here only. */
.takeaways {
  margin: var(--s8) 0 var(--s6);
  padding: var(--s4);
  background: var(--accent-soft);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius-sm);
}

.takeaways h2 {
  margin: 0 0 0.55rem !important;
  font-size: 0.95rem !important;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  line-height: 1.3;
}

.takeaways ul {
  margin: 0;
  padding-left: 1.15rem;
}

.takeaways li {
  margin: 0.28rem 0;
  font-size: 0.97rem;
  line-height: 1.5;
}

/* FAQ */
.faq {
  clear: both;
  margin: 0.5rem 0 0.5rem;
  padding-top: 0.25rem;
  border-top: 1px solid var(--border);
}

.faq > h2 {
  margin: 1rem 0 0.75rem !important;
  font-size: 1.35rem !important;
  letter-spacing: -0.01em;
}

.faq details {
  margin: 0;
  padding: var(--s3) 0;
  background: none;
  border: none;
  border-bottom: 1px solid var(--border);
  border-radius: 0;
}

.faq details:first-of-type {
  border-top: 1px solid var(--border);
}

.faq summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 0.98rem;
  line-height: 1.4;
}

.faq details p {
  margin: 0.55rem 0 0;
  font-size: 0.97rem;
  color: var(--text);
}

/* Prev / next summaries */
.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin: 1.75rem 0 0.5rem;
  clear: both;
}

.post-nav-link {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  padding: 0.85rem 1rem;
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--text);
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
  min-width: 0;
}

.post-nav-link:active {
  transform: scale(0.98);
}

.post-nav-link.next {
  text-align: right;
  grid-column: 2;
}

.post-nav-link.prev {
  grid-column: 1;
}

.post-nav-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
}

.post-nav-title {
  font-weight: 700;
  font-size: 0.95rem;
  line-height: 1.3;
  overflow: hidden;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.post-nav-meta {
  font-size: 0.8rem;
  color: var(--muted);
}

.post-nav-empty {
  display: none;
}

@media (max-width: 520px) {
  .post-nav {
    grid-template-columns: 1fr;
  }

  .post-nav-link.next,
  .post-nav-link.prev {
    grid-column: 1;
    text-align: left;
  }
}

/* Back to top + time-left — opacity only, no movement. Single thumb zone: right. */
#backTop {
  position: fixed;
  right: 1rem;
  bottom: 1rem;
  z-index: 60;
  width: 2.75rem;
  height: 2.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-pop) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

#backTop.is-visible {
  opacity: 1;
  pointer-events: auto;
}

#backTop:active {
  transform: scale(0.95);
}

/* Time-left readout (book pages) */
#timeLeft {
  position: fixed;
  left: 1rem;
  bottom: 1rem;
  z-index: 60;
  padding: 0.35rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--muted);
  font-size: var(--fs-xs);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-pop) var(--ease-out);
}

#timeLeft.is-visible {
  opacity: 1;
}

/* One thumb zone on narrow screens: back-to-top wins, time-left hides. */
@media (max-width: 520px) {
  #timeLeft {
    display: none;
  }
}

/* Prose */
.prose {
  max-width: none;
}

/* Simple content pages (About): cap line length but keep left edge
   aligned with the page title (cap the children, not the section,
   so auto margins don't center the narrowed column). */
section.wrap.prose > * {
  max-width: var(--prose);
}

.book-page .prose {
  margin-top: 0.5rem;
}

.prose h2 {
  margin: var(--s8) 0 var(--s3);
  font-size: var(--fs-xl);
  letter-spacing: -0.01em;
  line-height: 1.3;
  text-wrap: balance;
}

.prose h3 {
  margin: var(--s6) 0 var(--s2);
  font-size: var(--fs-lg);
  line-height: 1.35;
}

.prose p {
  margin: 0 0 1.1rem;
}

.prose ul,
.prose ol {
  margin: 0 0 1.1rem;
  padding-left: 1.35rem;
}

.prose li {
  margin-bottom: 0.35rem;
}

.prose blockquote {
  margin: var(--s6) 0;
  padding: var(--s3) var(--s4);
  border-left: 3px solid var(--border-strong);
  background: var(--surface-1);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--muted);
  font-style: italic;
}

.prose code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  background: var(--surface-inset);
  padding: 0.1em 0.35em;
  border-radius: var(--radius-sm);
}

.prose hr {
  border: 0;
  border-top: 1px solid var(--border);
  margin: 2rem 0;
}

.book-footer {
  max-width: none;
  width: 100%;
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.9rem;
}

.related {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

/* Pagination */
.pagination {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  justify-content: center;
  margin: 2rem 0 1rem;
}

.page-btn,
.page-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.75rem;
  min-height: 2.75rem;
  padding: 0.45rem 0.7rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

.page-btn:active,
.page-num:active {
  transform: scale(0.97);
}

.page-num.current {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.page-btn.disabled {
  opacity: 0.45;
  pointer-events: none;
}

.page-gap {
  align-self: center;
  color: var(--muted);
  padding: 0 0.2rem;
}

/* A-Z letter nav */
.letter-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin: 1rem 0 1.5rem;
}

.letter-nav a,
.letter-nav span {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.75rem;
  min-height: 2.75rem;
  padding: 0.35rem 0.6rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.9rem;
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

.letter-nav a:active {
  transform: scale(0.97);
}

.letter-nav a[aria-current="page"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.letter-nav span.disabled {
  opacity: 0.4;
}

.hero-stats {
  margin: 0 0 1.25rem;
  font-size: 0.95rem;
  color: var(--muted);
}

.hero-botd {
  margin: 0.6rem 0 0;
  font-size: 0.92rem;
}

.search-hint {
  margin: 0.6rem 0 0;
  font-size: 0.85rem;
}

.search-hint kbd {
  font-family: inherit;
  font-size: 0.8em;
  padding: 0.1em 0.4em;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  background: var(--bg-elev);
}

.tag-filter {
  margin: 0 0 1.25rem;
  max-width: 28rem;
}

.more-tags {
  margin-top: 1.25rem;
  padding: 0.7rem 0.9rem;
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.more-tags > summary {
  cursor: pointer;
  font-weight: 700;
  font-size: 0.95rem;
}

.more-tags .tag-cloud {
  margin-top: 0.75rem;
}
.tag-filter input {
  width: 100%;
  min-height: 2.75rem;
  padding: 0.7rem 0.9rem;
  font: inherit;
  font-size: 1rem;
  color: var(--text);
  background: var(--surface-1);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
}

/* Reader settings — collapsed by default so the 2,500-word read starts
   immediately. Same disclosure pattern as the TOC. */
.reader-settings {
  margin: 0 0 var(--s4);
  background: var(--surface-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.reader-settings > summary {
  cursor: pointer;
  padding: var(--s3) var(--s4);
  min-height: 2.75rem;
  font-weight: 600;
  font-size: 0.95rem;
}

.reader-controls {
  display: flex;
  flex-wrap: wrap;
  gap: var(--s2);
  align-items: center;
  margin: 0;
  padding: 0 var(--s4) var(--s3);
}

.rc-group {
  display: inline-flex;
  gap: 0.25rem;
}

.reader-controls button {
  padding: 0.3rem 0.6rem;
  min-height: 2.5rem;
  min-width: 2.5rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text);
  font-size: 0.85rem;
  cursor: pointer;
  transition: transform var(--dur-press) var(--ease-out), border-color var(--dur-press) var(--ease-out);
}

.reader-controls button:active {
  transform: scale(0.97);
}

.reader-controls button[aria-pressed="true"] {
  background: var(--surface-1);
  border-color: var(--accent);
  box-shadow: inset 0 -2px 0 var(--accent);
  font-weight: 700;
}

.prose[data-rsize="0"] { font-size: 0.95rem; }
.prose[data-rsize="2"] { font-size: 1.18rem; }
.prose[data-rsize="3"] { font-size: 1.32rem; }

.prose[data-rsize] .takeaways li,
.prose[data-rsize] .faq details p {
  font-size: 1em;
}

.prose[data-rnarrow="1"] > * {
  max-width: 40rem;
}

.prose[data-rserif="1"] {
  font-family: var(--font-serif);
}

/* Similar-books list (Books like X pages) */
.similar-list {
  list-style: none;
  margin: 0 0 1.5rem;
  padding: 0;
  display: grid;
  gap: 1rem;
}

.similar-row {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.9rem;
  transition: border-color var(--dur-press) var(--ease-out);
}

.similar-cover {
  flex: 0 0 72px;
  width: 72px;
  aspect-ratio: 2 / 3;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--surface-inset);
  border: 1px solid var(--border);
}

.similar-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.similar-body {
  min-width: 0;
  flex: 1;
}

.similar-title {
  margin: 0 0 0.15rem;
  font-size: 1.05rem;
  line-height: 1.35;
}

.similar-title a {
  color: var(--text);
  text-decoration: none;
}

.similar-title a:hover {
  color: var(--accent);
}

.similar-meta {
  margin: 0 0 0.35rem;
  font-size: 0.88rem;
  color: var(--muted);
}

.similar-reason {
  margin: 0 0 0.35rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent-strong);
}

.similar-exc {
  margin: 0;
  font-size: 0.92rem;
  color: var(--muted);
}

/* About stat grid */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(8.5rem, 1fr));
  gap: 0.6rem;
  margin: 1.25rem 0;
}

.stat-grid > div {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.75rem;
}

.stat-num {
  font-size: 1.4rem;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.stat-label {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
}

/* Stat bars (stats page) */
.stat-bars {
  display: grid;
  gap: 0.45rem;
}

.stat-bar-row {
  display: grid;
  grid-template-columns: minmax(9rem, 14rem) 1fr;
  gap: 0.75rem;
  align-items: center;
  font-size: 0.92rem;
}

.stat-bar-label {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.stat-bar {
  display: block;
  height: 0.65rem;
  background: var(--surface-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.stat-bar > span {
  display: block;
  height: 100%;
  background: var(--accent);
  border-radius: 0;
}

@media (max-width: 520px) {
  .stat-bar-row {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }
}

/* Heading copy-links */
.heading-link {
  margin-left: 0.5rem;
  font-size: 0.8em;
  text-decoration: none;
  opacity: 0;
  color: var(--muted);
}

h2:hover .heading-link,
h3:hover .heading-link,
.heading-link:focus-visible {
  opacity: 1;
}

.heading-link:hover {
  color: var(--accent);
}

/* Coarse pointers have no hover: keep copy-links discoverable. */
@media (hover: none), (pointer: coarse) {
  .heading-link {
    opacity: 0.65;
  }
}

/* Book rows (compact lists) */
.book-row-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.book-row {
  border-bottom: 1px solid var(--border);
}

.book-row-link {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  padding: 0.75rem 0.5rem;
  text-decoration: none;
  color: var(--text);
  border-radius: var(--radius-sm);
  transition: background-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

.book-row-link:active {
  transform: scale(0.99);
}

/* Compact rows reserve a fixed cover box so async covers never shift text. */
.book-row-cover {
  flex: 0 0 44px;
  width: 44px;
  aspect-ratio: 2 / 3;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background: var(--surface-inset);
  border: 1px solid var(--border);
}

.book-row-cover img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center;
  background: var(--surface-1);
}

.book-row-cover .cover-fallback {
  display: grid;
  place-items: center;
  width: 100%;
  height: 100%;
  min-height: 0;
  background: var(--surface-inset);
  color: var(--muted);
  font-size: 1.1rem;
  font-weight: 800;
  border-radius: 0;
}

.book-row-info {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  min-width: 0;
}

.book-row-title {
  font-weight: 700;
}

.book-row-meta {
  font-size: 0.875rem;
  color: var(--muted);
}

.book-row-arrow {
  margin-left: auto;
  color: var(--muted);
}

/* Search */
.search-page {
  padding-bottom: 3rem;
}

.search-results {
  margin-top: 1.25rem;
  display: grid;
  gap: 0.75rem;
}

.search-hit {
  display: flex;
  gap: 0.9rem;
  align-items: center;
  padding: 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  text-decoration: none;
  color: var(--text);
  transition: border-color var(--dur-press) var(--ease-out), transform var(--dur-press) var(--ease-out);
}

.search-hit:active {
  transform: scale(0.99);
}

.search-hit img {
  display: block;
  width: 54px;
  height: 81px;
  object-fit: cover;
  object-position: center;
  background: var(--surface-inset);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.search-hit .cover-fallback {
  display: grid;
  place-items: center;
  width: 54px;
  height: 81px;
  min-height: 0;
  background: var(--surface-inset);
  color: var(--muted);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.search-hit strong {
  display: block;
}

.search-hit .meta {
  font-size: 0.875rem;
  color: var(--muted);
}

.search-hit .exc {
  font-size: 0.875rem;
  color: var(--muted);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

mark {
  background: var(--accent-soft);
  color: inherit;
  padding: 0 0.1em;
  border-radius: 2px;
}

/* Autocomplete — occasional use, standard pop. Interruptible transition. */
.ac-list {
  position: absolute;
  top: calc(100% + 4px);
  left: 0;
  right: 0;
  z-index: 70;
  background: var(--surface-1);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-pop);
  overflow: hidden;
  transform-origin: top center;
  transition: opacity var(--dur-pop) var(--ease-out), transform var(--dur-pop) var(--ease-out), display var(--dur-pop) allow-discrete;
  @starting-style {
    opacity: 0;
    transform: translateY(-4px) scale(0.98);
  }
}

.ac-list[hidden] {
  display: none;
  opacity: 0;
  transform: translateY(-4px) scale(0.98);
}

.ac-item {
  display: block;
  padding: 0.5rem 0.8rem;
  text-decoration: none;
  color: var(--text);
}

.ac-item + .ac-item {
  border-top: 1px solid var(--border);
}

.ac-item[aria-selected="true"] {
  background: var(--surface-inset);
}

.ac-item strong {
  display: block;
  font-size: 0.95rem;
  font-weight: 600;
}

.ac-item span {
  font-size: 0.82rem;
  color: var(--muted);
}

/* Footer */
.site-footer {
  margin-top: 3rem;
  border-top: 1px solid var(--border);
  background: var(--surface-1);
}

.footer-inner {
  padding: 2rem 0;
  display: grid;
  gap: 1.25rem;
}

.footer-inner p {
  margin: 0.35rem 0 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.footer-inner nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.1rem;
}

.footer-inner nav a {
  text-decoration: none;
  font-weight: 600;
  font-size: 0.92rem;
}

.fine {
  font-size: 0.82rem !important;
}

/* Reading progress — transform only (GPU), set via scaleX in site.js */
#readProgress {
  position: fixed;
  top: 0;
  left: 0;
  height: 3px;
  width: 100%;
  background: var(--accent);
  z-index: 100;
  transform: scaleX(0);
  transform-origin: left center;
}

/* Hover is fine-pointer only: avoids sticky hover on touch. */
@media (hover: hover) and (pointer: fine) {
  a:hover {
    color: var(--accent-strong);
  }

  .site-nav a:hover {
    background: var(--surface-inset);
  }

  .btn:hover {
    border-color: var(--accent);
  }

  .btn-primary:hover {
    background: var(--accent-strong);
    border-color: var(--accent-strong);
    color: #fff;
  }

  .book-card:hover {
    border-color: var(--border-strong);
  }

  .book-card-title a:hover,
  .similar-title a:hover {
    color: var(--accent-strong);
  }

  .tag:hover,
  .page-btn:hover,
  .page-num:hover,
  .letter-nav a:hover,
  .post-nav-link:hover,
  .search-hit:hover,
  .similar-row:hover {
    border-color: var(--accent);
  }

  .book-row-link:hover {
    background: var(--surface-inset);
  }

  .ac-item:hover {
    background: var(--surface-inset);
  }

  .theme-toggle:hover,
  .reader-controls button:hover,
  #backTop:hover {
    border-color: var(--accent);
  }
}

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

  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    /* Keep opacity/color (comprehension), kill movement: no transform/position motion */
    transition-property: opacity, background-color, border-color, color, box-shadow !important;
    transition-duration: 150ms !important;
  }

  #readProgress {
    transform: none;
    width: 0;
  }

  .site-nav,
  .site-nav.open,
  .ac-list,
  .ac-list[hidden] {
    transform: none !important;
  }
}

@media print {
  .site-header,
  .site-footer,
  .hero-search,
  .hero-actions,
  .breadcrumbs,
  .badge-row,
  .pagination,
  .letter-nav,
  .tag-filter,
  .related,
  .post-nav,
  .reader-settings,
  .reader-controls,
  #readProgress,
  #timeLeft,
  #backTop {
    display: none !important;
  }

  .toc {
    width: 100%;
    page-break-inside: avoid;
  }

  body {
    background: #fff;
    color: #000;
  }
}