/* Y2HL site styles. Colours are tokens; dark mode redefines them. */
:root {
  --bg: #fbfaf7;
  --surface: #ffffff;
  --surface-2: #f3f1ec;
  --ink: #1b1e22;
  --muted: #5d636b;
  --line: #e4e0d8;
  --accent: #0f766e;
  --accent-strong: #0b5c56;
  --accent-ink: #ffffff;
  --accent-soft: #e2f1ee;
  --code-bg: #f6f4ef;
  --fill: #fff7e0;
  --fill-line: #e0b84f;
  --co1: #0f766e; --co2: #2563eb; --co3: #7c3aed; --co4: #c2410c; --co5: #b91c1c; --co6: #4d7c0f;
  --radius: 12px;
  --shadow: 0 1px 2px rgba(20, 20, 20, .04), 0 4px 16px rgba(20, 20, 20, .05);
  --font: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --serif: "Source Serif 4", Georgia, serif;
  --mono: "JetBrains Mono", ui-monospace, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #111417; --surface: #171b1f; --surface-2: #1e2328; --ink: #e8e6e1; --muted: #9ba2aa;
    --line: #2b3137; --accent: #2dd4bf; --accent-strong: #5eead4; --accent-ink: #062a26; --accent-soft: #12302c;
    --code-bg: #0d1117; --fill: #2a2412; --fill-line: #8a6d1f;
    --co1: #2dd4bf; --co2: #60a5fa; --co3: #a78bfa; --co4: #fb923c; --co5: #f87171; --co6: #a3e635;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 16px rgba(0, 0, 0, .25);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #111417; --surface: #171b1f; --surface-2: #1e2328; --ink: #e8e6e1; --muted: #9ba2aa;
  --line: #2b3137; --accent: #2dd4bf; --accent-strong: #5eead4; --accent-ink: #062a26; --accent-soft: #12302c;
  --code-bg: #0d1117; --fill: #2a2412; --fill-line: #8a6d1f;
  --co1: #2dd4bf; --co2: #60a5fa; --co3: #a78bfa; --co4: #fb923c; --co5: #f87171; --co6: #a3e635;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 4px 16px rgba(0, 0, 0, .25);
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 84px; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.65 var(--font); }
img { max-width: 100%; }
a { color: var(--accent); text-underline-offset: 3px; }
a:hover { color: var(--accent-strong); }
h1, h2, h3 { font-family: var(--serif); line-height: 1.2; letter-spacing: -.01em; }
h1 { font-size: clamp(2rem, 4.5vw, 3rem); margin: .2em 0 .3em; }
h2 { font-size: clamp(1.4rem, 2.6vw, 1.8rem); }
code, pre { font-family: var(--mono); font-size: .88em; }
.muted { color: var(--muted); }
.skip { position: absolute; left: -999px; }
.skip:focus { left: 16px; top: 8px; z-index: 50; background: var(--surface); padding: 8px 12px; border-radius: 8px; }

.wrap { width: min(1180px, 100% - 32px); margin-inline: auto; }
.wrap.narrow { width: min(760px, 100% - 32px); }
.section { padding: 40px 0; }

/* Header and footer */
.site-header { position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--bg) 88%, transparent); backdrop-filter: blur(10px); border-bottom: 1px solid var(--line); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; gap: 16px; }
.brand { display: flex; align-items: center; gap: 10px; color: var(--ink); text-decoration: none; }
.brand span { display: flex; flex-direction: column; line-height: 1.1; }
.brand strong { font-size: 1.1rem; letter-spacing: .02em; }
.brand small { color: var(--muted); font-size: .75rem; }
.main-nav { display: flex; align-items: center; gap: 4px; }
.main-nav a { color: var(--ink); text-decoration: none; padding: 8px 12px; border-radius: 8px; font-weight: 500; font-size: .95rem; }
.main-nav a:hover, .main-nav a[aria-current] { background: var(--surface-2); }
.theme-toggle { border: 1px solid var(--line); background: var(--surface); color: var(--ink); border-radius: 8px; width: 36px; height: 36px; display: grid; place-items: center; cursor: pointer; margin-left: 6px; }
.site-footer { border-top: 1px solid var(--line); margin-top: 48px; padding: 28px 0; color: var(--muted); font-size: .9rem; }
.footer-inner { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-inner p { margin: 0; }
.footer-inner p:last-child { text-align: right; }

/* Buttons, tags, stats */
.actions { display: flex; gap: 12px; flex-wrap: wrap; margin-top: 24px; }
.btn { display: inline-flex; align-items: center; padding: 10px 18px; border-radius: 10px; border: 1px solid var(--line); background: var(--surface); color: var(--ink); text-decoration: none; font-weight: 600; font-size: .95rem; }
.btn:hover { border-color: var(--accent); color: var(--ink); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { background: var(--accent-strong); color: var(--accent-ink); }
.tag { display: inline-block; font-size: .75rem; font-weight: 600; padding: 3px 9px; border-radius: 999px; background: var(--accent-soft); color: var(--accent); }
.tag.soft { background: var(--surface-2); color: var(--muted); }
.eyebrow { text-transform: uppercase; letter-spacing: .08em; font-size: .78rem; font-weight: 600; color: var(--accent); margin: 0; display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.lead { font-size: 1.15rem; color: var(--muted); max-width: 68ch; }
.stats { list-style: none; padding: 0; margin: 16px 0 0; display: flex; flex-wrap: wrap; gap: 6px 18px; color: var(--muted); font-size: .9rem; }
.stats strong { color: var(--ink); }
.stats.big { gap: 12px; margin-top: 24px; }
.stats.big li { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px 16px; display: flex; flex-direction: column; min-width: 96px; }
.stats.big strong { font-family: var(--serif); font-size: 1.8rem; line-height: 1.1; }
.co { display: inline-block; font: 600 .72rem/1 var(--font); letter-spacing: .04em; padding: 4px 7px; border-radius: 6px; color: #fff; background: var(--co1); }
.co-co2 { background: var(--co2); } .co-co3 { background: var(--co3); } .co-co4 { background: var(--co4); } .co-co5 { background: var(--co5); } .co-co6 { background: var(--co6); }
:root[data-theme="dark"] .co { color: #0b0d10; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .co { color: #0b0d10; } }

/* Home */
.hero { padding: 72px 0 48px; background: radial-gradient(1000px 400px at 85% -10%, var(--accent-soft), transparent 70%); border-bottom: 1px solid var(--line); }
.hero h1 { max-width: 18ch; font-size: clamp(2.2rem, 6vw, 3.6rem); }
.section-head { display: flex; justify-content: space-between; align-items: baseline; gap: 16px; flex-wrap: wrap; }
.course-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 20px; }
.course-card { display: flex; flex-direction: column; gap: 4px; padding: 24px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); color: var(--ink); text-decoration: none; transition: border-color .15s, transform .15s; }
.course-card:hover { border-color: var(--accent); transform: translateY(-2px); color: var(--ink); }
.course-card h3 { font-size: 1.4rem; margin: 12px 0 0; }
.course-card p { margin: 6px 0; }
.course-card-top { display: flex; gap: 6px; }
.course-tagline { color: var(--accent); font-weight: 600; }
.card-link { margin-top: auto; padding-top: 12px; color: var(--accent); font-weight: 600; }
.three { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; }
.three > div { padding: 20px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.three h3 { margin: 10px 0 6px; font-size: 1.15rem; }
.three p { margin: 0; color: var(--muted); }
.num { display: grid; place-items: center; width: 32px; height: 32px; border-radius: 50%; background: var(--accent-soft); color: var(--accent); font-weight: 700; }
.about-teaser > div { display: flex; gap: 24px; align-items: center; padding: 28px; border-radius: var(--radius); background: var(--surface-2); }
.about-teaser .photo-frame { flex: none; width: 128px; padding: 5px; }
.about-teaser h2 { margin: 6px 0; }

/* Photo mat: an accent-tinted frame so a white-background portrait doesn't bleed into the page. */
.photo-frame { padding: 8px; border-radius: 18px; background: linear-gradient(145deg, var(--accent), var(--accent-soft)); box-shadow: 0 12px 28px rgba(0, 0, 0, .14); }
.photo-frame img { display: block; width: 100%; height: auto; border-radius: 12px; border: 3px solid var(--surface); }

.profile { display: grid; grid-template-columns: 210px 1fr; gap: 28px; align-items: start; margin: 8px 0 32px; padding: 24px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); }
.profile p { margin: 0; }
.profile-name { font-size: 1.4rem; font-weight: 700; }
.profile-role { color: var(--muted); margin-top: 4px !important; }
.profile-facts { margin: 14px 0 0; padding-left: 1.1em; }
.profile-facts li { margin: 3px 0; }

.book { display: grid; grid-template-columns: 180px 1fr; gap: 28px; align-items: start; padding: 24px; background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: var(--shadow); }
.book + .book { margin-top: 16px; }
.book-cover img { display: block; width: 100%; height: auto; border-radius: 4px; box-shadow: 0 12px 28px rgba(0, 0, 0, .22); }
.book .eyebrow { margin: 0; }
.prose .book-title, .book-title { margin: 4px 0 2px; padding: 0; border: 0; font-size: 1.45rem; }
.book-by { margin: 0 0 12px; color: var(--muted); }
.book-details { color: var(--muted); font-size: .9rem; }
.book-reviews { grid-column: 1 / -1; display: flex; flex-wrap: wrap; gap: 12px; padding-top: 18px; border-top: 1px solid var(--line); }
.book-reviews .eyebrow { flex: 1 0 100%; }
.book-reviews figure { flex: 1 1 260px; margin: 0; padding: 14px 16px; border-left: 3px solid var(--accent); background: var(--surface-2); border-radius: 0 var(--radius) var(--radius) 0; }
.prose .book-reviews blockquote, .book-reviews blockquote { margin: 0 0 8px; padding: 0; border: 0; background: none; font-size: 1rem; font-style: italic; }
.book-reviews figcaption { color: var(--muted); font-size: .88rem; }

.pubs { padding-left: 2.2em; }
.pubs li { margin: 0 0 16px; padding-left: 4px; font-weight: 600; line-height: 1.45; }
.pubs li::marker { color: var(--muted); font-weight: 500; font-variant-numeric: tabular-nums; }
.pub-authors, .pub-venue { display: block; font-weight: 400; font-size: .92rem; color: var(--muted); }
.pub-authors strong { color: var(--ink); }

/* Page heads */
.page-head, .course-hero { padding: 48px 0 24px; border-bottom: 1px solid var(--line); }
.course-hero { padding-bottom: 40px; background: radial-gradient(900px 360px at 90% -20%, var(--accent-soft), transparent 70%); }
.crumbs { font-size: .88rem; color: var(--muted); margin: 0 0 12px; }
.crumbs a { color: var(--muted); }

/* Course landing */
.co-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 16px; margin-top: 16px; }
.co-col { display: flex; flex-direction: column; gap: 8px; }
.co-head { margin: 0 0 2px; display: flex; gap: 8px; align-items: center; font-weight: 600; font-size: .92rem; }
.week-card { position: relative; display: flex; flex-direction: column; padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 10px; text-decoration: none; color: var(--ink); }
.week-card:hover { border-color: var(--accent); color: var(--ink); }
.wk-num { font-size: .78rem; color: var(--muted); font-weight: 600; }
.wk-name { font-weight: 600; line-height: 1.35; }
.done-badge { display: none; position: absolute; top: 12px; right: 12px; font-size: .7rem; font-weight: 700; color: var(--accent); background: var(--accent-soft); padding: 2px 8px; border-radius: 999px; }
.is-done .done-badge { display: inline-block; }
.guide-links { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 16px; }
.guide-links a { display: flex; flex-direction: column; gap: 4px; padding: 18px; border-radius: var(--radius); border: 1px solid var(--line); background: var(--surface); text-decoration: none; color: var(--ink); }
.guide-links a:hover { border-color: var(--accent); }
.guide-links span { color: var(--muted); font-size: .92rem; }

/* Course layout with sidebar */
.course-layout { display: grid; grid-template-columns: 280px minmax(0, 1fr); gap: 40px; padding-top: 32px; align-items: start; }
.course-nav { position: sticky; top: 84px; max-height: calc(100vh - 100px); overflow: auto; }
.course-nav-box > summary { display: none; }
.course-nav-body { font-size: .92rem; padding-bottom: 24px; }
.nav-title { font-weight: 700; margin: 0 0 8px; }
.nav-title a { color: var(--ink); text-decoration: none; }
.course-nav ul { list-style: none; margin: 0 0 12px; padding: 0; }
.course-nav li a { display: flex; gap: 10px; align-items: baseline; padding: 6px 10px; border-radius: 8px; color: var(--ink); text-decoration: none; }
.course-nav li a:hover { background: var(--surface-2); }
.course-nav li a[aria-current] { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.nav-group { display: flex; gap: 8px; align-items: center; margin: 14px 0 4px; color: var(--muted); font-size: .8rem; font-weight: 600; }
.wk { flex: 0 0 20px; text-align: right; color: var(--muted); font-variant-numeric: tabular-nums; }
.wk-title { flex: 1; }
.done-dot { width: 8px; height: 8px; border-radius: 50%; flex: 0 0 8px; align-self: center; }
.is-done .done-dot { background: var(--accent); }
.course-main { min-width: 0; padding-bottom: 24px; }
.course-main > h1 { margin-top: 8px; }
.reqs { display: flex; flex-wrap: wrap; gap: 6px; align-items: center; color: var(--muted); font-size: .9rem; }
.chip { font: 500 .8rem var(--mono); padding: 2px 8px; border-radius: 6px; border: 1px solid var(--line); background: var(--surface); text-decoration: none; }

/* Week "at a glance" */
.glance { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 14px; margin: 24px 0; }
.glance section { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px 18px; }
.glance h2 { font: 700 .78rem var(--font); text-transform: uppercase; letter-spacing: .08em; color: var(--accent); margin: 0 0 8px; }
.glance ul, .glance ol { margin: 0; padding-left: 18px; }
.glance p { margin: 0 0 6px; }
.glance details { border-top: 1px solid var(--line); padding: 8px 0; }
.glance details:first-of-type { border-top: 0; padding-top: 0; }
.glance summary { cursor: pointer; }
.toc { border-left: 3px solid var(--accent); background: var(--surface-2); border-radius: 0 var(--radius) var(--radius) 0; padding: 12px 18px; margin: 24px 0 8px; }
.toc p { margin: 0 0 6px; font-weight: 700; font-size: .85rem; text-transform: uppercase; letter-spacing: .06em; color: var(--muted); }
.toc ul { margin: 0; padding-left: 18px; }
.toc li { margin: 2px 0; }

/* Long-form content */
.prose { max-width: 820px; }
.prose h2 { margin-top: 2em; }
.prose h3 { font-size: 1.35rem; margin: 2.2em 0 .6em; padding-top: 1em; border-top: 1px solid var(--line); }
.prose > h3:first-child { border-top: 0; margin-top: 1em; }
.prose p, .prose li { max-width: 72ch; }
.prose :not(pre) > code { background: var(--code-bg); border: 1px solid var(--line); border-radius: 5px; padding: .08em .35em; overflow-wrap: anywhere; }
.prose blockquote { margin: 1.2em 0; padding: 14px 20px; border-left: 4px solid var(--accent); background: var(--accent-soft); border-radius: 0 var(--radius) var(--radius) 0; font-size: 1.05rem; }
.prose blockquote p { margin: 0; }
.prose pre { position: relative; background: var(--code-bg); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; overflow-x: auto; line-height: 1.5; }
.prose pre code.hljs { background: transparent; padding: 0; }
.copy-btn { position: absolute; top: 8px; right: 8px; font: 600 .72rem var(--font); padding: 4px 8px; border-radius: 6px; border: 1px solid var(--line); background: var(--surface); color: var(--muted); cursor: pointer; opacity: 0; transition: opacity .15s; }
.prose pre:hover .copy-btn, .copy-btn:focus { opacity: 1; }
.table-wrap { overflow-x: auto; margin: 1.2em 0; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.prose table { border-collapse: collapse; width: 100%; font-size: .92rem; }
.prose th, .prose td { text-align: left; vertical-align: top; padding: 10px 12px; border-bottom: 1px solid var(--line); }
.prose th { background: var(--surface-2); font-weight: 600; white-space: nowrap; }
.prose tr:last-child td { border-bottom: 0; }
.prose td:first-child { white-space: nowrap; color: var(--muted); font-variant-numeric: tabular-nums; }
.prose strong:first-child { color: var(--ink); }
.fill { display: block; min-width: 110px; min-height: 1.6em; background: var(--fill); border-bottom: 2px dashed var(--fill-line); border-radius: 4px; }
.worksheet-note { display: inline-block; font-size: .85rem; font-weight: 600; color: var(--muted); background: var(--fill); border: 1px dashed var(--fill-line); padding: 4px 10px; border-radius: 8px; margin-bottom: 0; }

/* Week footer */
.mark-done { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 16px; margin: 40px 0 16px; padding: 16px 18px; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
.mark-done label { font-weight: 600; display: flex; gap: 10px; align-items: center; cursor: pointer; }
.mark-done input { width: 18px; height: 18px; accent-color: var(--accent); }
.pager { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.pager a { display: flex; flex-direction: column; padding: 16px 18px; border: 1px solid var(--line); border-radius: var(--radius); text-decoration: none; color: var(--ink); font-weight: 600; background: var(--surface); }
.pager a:hover { border-color: var(--accent); }
.pager span { color: var(--muted); font-size: .82rem; font-weight: 500; }
.pager .next { text-align: right; }

@media (max-width: 900px) {
  .course-layout { grid-template-columns: 1fr; gap: 8px; padding-top: 16px; }
  .course-nav { position: static; max-height: none; }
  .course-nav-box { border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
  .course-nav-box > summary { display: flex; justify-content: space-between; padding: 12px 16px; cursor: pointer; font-weight: 600; }
  .course-nav-body { padding: 0 12px 12px; }
  .progress-label { color: var(--muted); font-weight: 500; font-size: .85rem; }
}
@media (max-width: 600px) {
  body { font-size: 15.5px; }
  .brand small { display: none; }
  .main-nav a { padding: 8px; }
  .hero { padding: 48px 0 32px; }
  .pager { grid-template-columns: 1fr; }
  .pager .next { text-align: left; }
  .footer-inner p:last-child { text-align: left; }
  .prose td:first-child { white-space: normal; }
  .profile { grid-template-columns: 1fr; padding: 18px; }
  .profile .photo-frame { max-width: 190px; }
  .book { grid-template-columns: 1fr; padding: 18px; }
  .book-cover { max-width: 160px; }
  .about-teaser > div { flex-direction: column; align-items: flex-start; }
}
@media print {
  .site-header, .site-footer, .course-nav, .pager, .mark-done, .copy-btn, .theme-toggle { display: none !important; }
  .course-layout { display: block; }
  body { background: #fff; color: #000; }
  .table-wrap { overflow: visible; }
}