:root {
    --paper: #F8F9F8;
    --ink: #1B2433;
    --ink-soft: #4B5563;
    --rule: #D9DDE3;
    --link: #2F4A66;
    --panel: #EEF1F4;
    --serif: "Newsreader", Georgia, "Times New Roman", serif;
    --sans: "Public Sans", "Helvetica Neue", Arial, sans-serif;
  }
  @media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
      --paper: #121821;
      --ink: #E5E8EC;
      --ink-soft: #A3ACB8;
      --rule: #2C3542;
      --link: #9DB8D4;
      --panel: #1A222D;
    }
  }
  :root[data-theme="dark"] {
    --paper: #121821;
    --ink: #E5E8EC;
    --ink-soft: #A3ACB8;
    --rule: #2C3542;
    --link: #9DB8D4;
    --panel: #1A222D;
  }

  * { box-sizing: border-box; }
  html { -webkit-text-size-adjust: 100%; }
  body {
    margin: 0;
    background: var(--paper);
    color: var(--ink);
    font-family: var(--serif);
    font-size: 1.1875rem;
    line-height: 1.6;
    font-optical-sizing: auto;
  }
  a { color: var(--link); text-underline-offset: 0.18em; text-decoration-thickness: 1px; }
  a:hover { text-decoration-thickness: 2px; }
  a:focus-visible { outline: 2px solid var(--link); outline-offset: 3px; border-radius: 2px; }

  .wrap { max-width: 1120px; margin: 0 auto; padding: 0 16px; }

  /* Header */
  .site-header {
    display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between;
    gap: 12px 32px; padding: 28px 0 20px; border-bottom: 1px solid var(--rule);
  }
  .brand { text-decoration: none; color: var(--ink); }
  .brand-name { font-family: var(--serif); font-size: 1.5rem; font-weight: 500; letter-spacing: -0.01em; }
  .brand-press { display: block; font-family: var(--sans); font-size: 0.8125rem; color: var(--ink-soft); margin-top: 2px; }
  .site-nav { display: flex; flex-wrap: wrap; gap: 6px 24px; font-family: var(--sans); font-size: 0.9375rem; }
  .site-nav a { color: var(--ink); text-decoration: none; padding: 4px 0; border-bottom: 1px solid transparent; }
  .site-nav a:hover { border-bottom-color: var(--ink); }

  /* Layout */
  .layout {
    display: grid; grid-template-columns: minmax(0, 1fr);
    grid-template-areas: "intro" "aside" "rest";
    row-gap: 48px; padding: 56px 0 80px;
  }
  .intro { grid-area: intro; }
  .aside { grid-area: aside; }
  .rest { grid-area: rest; }
  .intro, .rest { max-width: 680px; min-width: 0; }
  .rest > section:first-child { margin-top: 24px; }
  @media (min-width: 900px) {
    .layout {
      grid-template-columns: minmax(0, 1fr) 300px; column-gap: 72px; row-gap: 0;
      grid-template-areas: "intro aside" "rest aside";
      grid-template-rows: auto 1fr;
    }
    .aside { position: sticky; top: 32px; align-self: start; }
    .rest > section:first-child { margin-top: 72px; }
  }

  /* Opening statement: the one bold element */
  .opening {
    font-family: var(--serif);
    font-weight: 300;
    font-size: clamp(2.125rem, 1.4rem + 3vw, 3.5rem);
    line-height: 1.12;
    letter-spacing: -0.02em;
    margin: 0 0 32px;
    max-width: 18ch;
    text-wrap: balance;
  }
  .lede p { margin: 0 0 1.1em; }
  .lede p:first-child { font-size: 1.3125rem; line-height: 1.55; }

  /* Sections */
  section { margin-top: 72px; }
  h2 {
    font-family: var(--serif); font-weight: 500; font-size: 1.75rem; line-height: 1.25;
    letter-spacing: -0.01em; margin: 0 0 8px;
  }
  .section-intro { color: var(--ink-soft); margin: 0 0 32px; }
  h3 { font-family: var(--serif); font-weight: 500; font-size: 1.3125rem; line-height: 1.3; margin: 0 0 6px; }
  p { margin: 0 0 1em; }

  /* Featured book */
  .book {
    border-left: 3px solid var(--ink);
    padding: 4px 0 4px 24px;
    margin: 0 0 40px;
  }
  .book-title { font-size: 2rem; font-weight: 400; letter-spacing: -0.015em; line-height: 1.15; margin: 0; }
  .book-subtitle { font-style: italic; color: var(--ink-soft); margin: 6px 0 18px; font-size: 1.1875rem; }
  .actions { display: flex; flex-wrap: wrap; gap: 10px 24px; font-family: var(--sans); font-size: 0.9375rem; margin-top: 4px; }

  .upcoming { display: grid; gap: 28px; }
  .upcoming h3 { font-size: 1.1875rem; }
  .upcoming p { color: var(--ink-soft); margin: 0; }

  /* Projects */
  .projects { list-style: none; margin: 0; padding: 0; }
  .project { padding: 28px 0; border-top: 1px solid var(--rule); }
  .project:last-child { border-bottom: 1px solid var(--rule); }
  .project p { margin: 0 0 12px; }
  .project-meta { font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft); margin: 0; display: flex; flex-wrap: wrap; gap: 4px 20px; }
  .figure { font-variant-numeric: tabular-nums; color: var(--ink); font-weight: 500; }
  .more { margin-top: 24px; color: var(--ink-soft); }

  /* Research */
  .citation { padding-left: 24px; border-left: 1px solid var(--rule); }
  .citation p { margin: 0 0 8px; }
  .citation .ref { font-size: 1.0625rem; color: var(--ink-soft); }

  /* About */
  .credentials { list-style: none; padding: 0; margin: 0 0 24px; }
  .credentials li { padding: 6px 0; }

  /* Aside */
  .aside-panel { background: var(--panel); padding: 28px 24px; border-radius: 4px; }
  .aside h2 { font-size: 1.375rem; margin-bottom: 4px; }
  .aside .note { font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft); margin: 0 0 24px; line-height: 1.5; }
  .free { padding: 20px 0; border-top: 1px solid var(--rule); }
  .free:last-child { padding-bottom: 0; }
  .free h3 { font-size: 1.125rem; margin-bottom: 6px; }
  .free .free-subtitle { font-style: italic; margin-bottom: 8px; }
  .free p { font-size: 1rem; line-height: 1.55; color: var(--ink-soft); margin: 0 0 10px; }
  .status { font-family: var(--sans); font-size: 0.8125rem; color: var(--ink-soft); }
  .free a { font-family: var(--sans); font-size: 0.9375rem; }

  /* Footer */
  .site-footer {
    border-top: 1px solid var(--rule); padding: 24px 0 40px;
    font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft);
    display: flex; flex-wrap: wrap; justify-content: space-between; gap: 8px 24px;
  }
  .site-footer a { color: var(--ink-soft); }

  @media (max-width: 600px) {
    body { font-size: 1.125rem; }
    .site-header { padding-top: 20px; }
    .layout { padding-top: 36px; }
    section { margin-top: 56px; }
    .book { padding-left: 16px; }
    .book-title { font-size: 1.75rem; }
  }

  /* Book page */
  .crumb { font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft); margin: 0 0 20px; }
  .crumb a { color: var(--ink-soft); }
  .book-hero-sub { font-style: italic; color: var(--ink-soft); font-size: 1.3125rem; margin: -16px 0 24px; max-width: 34ch; }
  .facts { list-style: none; padding: 0; margin: 0 0 28px; display: flex; flex-wrap: wrap; gap: 8px 32px; font-family: var(--sans); font-size: 0.9375rem; color: var(--ink-soft); }
  .facts strong { color: var(--ink); font-weight: 600; }
  .notice { font-family: var(--sans); font-size: 0.9375rem; background: var(--panel); border-radius: 4px; padding: 14px 18px; margin: 0 0 8px; }
  .steps { padding-left: 1.4em; margin: 0 0 1em; }
  .steps li { margin-bottom: 10px; }

  .picker { background: var(--panel); border-radius: 4px; padding: 24px; }
  .picker label { display: block; font-family: var(--sans); font-size: 0.9375rem; font-weight: 600; margin-bottom: 8px; }
  .picker select {
    width: 100%; font-family: var(--sans); font-size: 1rem; color: var(--ink);
    background: var(--paper); border: 1px solid var(--rule); border-radius: 4px; padding: 10px 12px;
  }
  .picker select:focus-visible { outline: 2px solid var(--link); outline-offset: 2px; }
  .request-text {
    font-family: var(--serif); font-size: 1.0625rem; line-height: 1.55; background: var(--paper);
    border-left: 3px solid var(--ink); padding: 16px 18px; margin: 18px 0 12px; white-space: pre-wrap;
  }
  .checkin { font-size: 1rem; color: var(--ink-soft); margin: 16px 0 0; }
  .checkin q { color: var(--ink); }
  .row { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 16px; font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft); }
  .btn {
    font-family: var(--sans); font-size: 0.9375rem; font-weight: 500; color: var(--paper); background: var(--ink);
    border: 0; border-radius: 4px; padding: 9px 16px; cursor: pointer;
  }
  .btn:hover { opacity: 0.9; }
  .btn:focus-visible { outline: 2px solid var(--link); outline-offset: 3px; }
  .btn.secondary { background: transparent; color: var(--ink); border: 1px solid var(--ink); }

  .tool-group { padding: 24px 0; border-top: 1px solid var(--rule); }
  .tool-group:last-of-type { border-bottom: 1px solid var(--rule); }
  .tool-group h3 { margin-bottom: 4px; }
  .tool-group .for { font-family: var(--sans); font-size: 0.875rem; color: var(--ink-soft); margin: 0 0 12px; }
  .tool-group ul { margin: 0; padding-left: 1.2em; }
  .tool-group li { margin-bottom: 8px; }
  .sources { font-size: 1rem; color: var(--ink-soft); padding-left: 1.2em; }
  .sources li { margin-bottom: 6px; overflow-wrap: anywhere; }
  .free-title { color: var(--ink); text-decoration: none; }
  .free-title:hover { text-decoration: underline; }
  .free .free-link { margin: 10px 0 0; }

  /* Book cover (Climb It or Go Around It) */
  .cover {
    background: #16272B; color: #F1F3EF; border-radius: 4px;
    aspect-ratio: 2 / 3; padding: 28px 24px 22px; margin-bottom: 24px;
    display: flex; flex-direction: column; justify-content: space-between; gap: 16px;
    box-shadow: 0 1px 2px rgba(22, 39, 43, 0.25), 0 8px 24px rgba(22, 39, 43, 0.18);
  }
  .cover .ct { font-family: var(--sans); font-weight: 600; font-size: 1.875rem; line-height: 1.05; letter-spacing: -0.015em; text-wrap: balance; }
  .cover .cs { font-family: var(--serif); font-size: 0.9375rem; line-height: 1.4; opacity: 0.85; margin-top: 12px; }
  .cover svg { width: 100%; height: auto; display: block; }
  .cover .ca { font-family: var(--sans); font-weight: 500; font-size: 0.9375rem; letter-spacing: 0.02em; }
  @media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .cover { box-shadow: none; border: 1px solid var(--rule); } }
  :root[data-theme="dark"] .cover { box-shadow: none; border: 1px solid var(--rule); }
  @media (max-width: 899px) { .cover { max-width: 300px; } }