/* ---------- Design tokens (matched to gwern.net) ---------- */
:root {
  /* Gwern font stacks — verbatim */
  --serif: "Source Serif 4", "Apple Garamond", "Baskerville", "Libre Baskerville", "Droid Serif", "Times New Roman", "Times", serif, "Noto Emoji", "Quivira";
  --sans:  "Source Sans 3", "Lucida Sans Unicode", "Helvetica", "Trebuchet MS", sans-serif, "Noto Emoji", "Quivira";
  --mono:  "IBM Plex Mono", "Liberation Mono", "Consolas", "Courier", monospace, "Noto Emoji", "Quivira";

  /* Gwern body size + line-height breakpoints */
  --body-font-size: 20px;
  --line-height: 1.60;

  /* Gwern layout */
  --page-max: 935px;
  --side-pad: 20px;

  /* Colors — gwern is monochrome white/black */
  --bg: #ffffff;
  --bg-elev: #f8f8f8;
  --ink: #000000;
  --ink-soft: #333333;
  --muted: #666666;
  --rule: #cccccc;
  --accent: #333333;
  --accent-hover: #888888;
  --accent-visited: #666666;
  --tag-bg: #f0f0f0;
  --code-bg: #fafafa;
}

@media all and (max-width: 1199px) { :root { --line-height: 1.55; } }
@media all and (max-width: 999px)  { :root { --line-height: 1.50; } }
@media all and (max-width: 649px)  {
  :root {
    --body-font-size: 18px;
    --line-height: 1.45;
    --side-pad: 16px;
  }
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --bg: #181818;
    --bg-elev: #222222;
    --ink: #e8e8e8;
    --ink-soft: #cfcfcf;
    --muted: #9a9a9a;
    --rule: #3a3a3a;
    --accent: #d0d0d0;
    --accent-hover: #ffffff;
    --accent-visited: #a8a8a8;
    --tag-bg: #262626;
    --code-bg: #262626;
  }
}
:root[data-theme="dark"] {
  --bg: #181818;
  --bg-elev: #222222;
  --ink: #e8e8e8;
  --ink-soft: #cfcfcf;
  --muted: #9a9a9a;
  --rule: #3a3a3a;
  --accent: #d0d0d0;
  --accent-hover: #ffffff;
  --accent-visited: #a8a8a8;
  --tag-bg: #262626;
  --code-bg: #262626;
}
:root[data-theme="light"] {
  --bg: #ffffff;
  --bg-elev: #f8f8f8;
  --ink: #000000;
  --ink-soft: #333333;
  --muted: #666666;
  --rule: #cccccc;
  --accent: #333333;
  --accent-hover: #888888;
  --accent-visited: #666666;
  --tag-bg: #f0f0f0;
  --code-bg: #fafafa;
}

/* ---------- Reset ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 5rem; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--serif);
  font-size: var(--body-font-size);
  font-weight: 400;
  line-height: var(--line-height);
  -webkit-font-smoothing: antialiased;
  font-feature-settings: "kern", "liga";
  font-variant-numeric: oldstyle-nums;   /* gwern old-style figures */
  text-rendering: optimizeLegibility;
  overflow-wrap: break-word;
}

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.topnav {
  max-width: var(--page-max);
  margin: 0 auto;
  padding: 0.9rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-family: var(--sans);
}
.brand {
  font-family: var(--serif);
  font-weight: 600;
  font-size: 1em;
  color: var(--ink);
  text-decoration: none;
  font-variant-caps: small-caps;
  letter-spacing: 0.02em;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 1.25rem;
}
.nav-links a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.9em;
  font-weight: 400;
  transition: color 0.15s ease;
}
.nav-links a:hover { color: var(--accent); }

#theme-toggle {
  background: transparent;
  border: 1px solid var(--rule);
  border-radius: 999px;
  width: 34px;
  height: 34px;
  cursor: pointer;
  color: var(--ink-soft);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  transition: border-color 0.15s ease, color 0.15s ease, transform 0.15s ease;
}
#theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: rotate(20deg);
}

/* ---------- Layout ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 3rem var(--side-pad) 4rem;
  display: grid;
  grid-template-columns: 14rem minmax(0, 1fr);
  gap: 3rem;
  align-items: start;
}

/* ---------- Table of Contents ---------- */
.toc {
  position: sticky;
  top: 5rem;
  font-family: var(--sans);
  font-size: 0.85rem;
  max-height: calc(100vh - 6rem);
  overflow-y: auto;
}
.toc-title {
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 0.72rem;
  color: var(--muted);
  margin-bottom: 0.75rem;
  font-weight: 600;
}
.toc ol {
  list-style: none;
  padding: 0;
  margin: 0;
  border-left: 1px solid var(--rule);
}
.toc ol ol {
  border-left: none;
  margin-top: 0.25rem;
  padding-left: 0.75rem;
}
.toc li { margin: 0.25rem 0; }
.toc a {
  display: block;
  padding: 0.2rem 0.75rem;
  color: var(--ink-soft);
  text-decoration: none;
  border-left: 2px solid transparent;
  margin-left: -1px;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.toc a:hover { color: var(--accent); }
.toc a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 600;
}

/* ---------- Prose column ---------- */
.prose {
  max-width: var(--page-max);
  min-width: 0;
}
.prose h1, .prose h2, .prose h3, .prose h4 {
  font-family: var(--serif);
  color: var(--ink);
  line-height: 1.15;
}
/* H1 — gwern page title: small-caps, weight 600, letter-spacing -1px */
.page-title {
  font-size: 2em;
  font-weight: 600;
  margin: 0 0 0.25rem;
  text-align: center;
  line-height: 1.15;
  font-variant-caps: small-caps;
  letter-spacing: -1px;
}
@media all and (max-width: 649px) {
  .page-title { font-size: 1.75em; }
}
.subtitle {
  font-family: var(--serif);
  color: var(--muted);
  font-size: 1em;
  margin: 0 0 2rem;
  text-align: center;
  font-style: italic;
}

/* H2 — gwern: 1.4em, uppercase, dotted border-bottom */
.prose h2 {
  font-size: 1.4em;
  font-weight: 600;
  margin: 2.5rem 0 1rem;
  padding-bottom: 0.05em;
  text-transform: uppercase;
  letter-spacing: 0.02em;
  border-bottom: 1px dotted var(--ink-soft);
}
/* H3 — gwern: 1.35em, bold */
.prose h3 {
  font-size: 1.35em;
  font-weight: 700;
  margin: 1.75rem 0 0.5rem;
}
/* H4 — gwern: 1.2em */
.prose h4 {
  font-size: 1.2em;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
}
.prose p { margin: 0 0 1em; color: var(--ink); }
/* Gwern-style links: dark gray, underlined */
.prose a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color 0.15s ease;
}
.prose a:hover { color: var(--accent-hover); }
.prose a:visited { color: var(--accent-visited); }

/* ---------- Epigraph ---------- */
.epigraph {
  font-family: var(--serif);
  font-style: italic;
  color: var(--ink-soft);
  border-left: 3px solid var(--rule);
  padding: 0.25rem 0 0.25rem 1.25rem;
  margin: 0 auto 2.5rem;
  max-width: 560px;
  font-size: 0.95em;
}
.epigraph p { margin: 0 0 0.35rem; }
.epigraph cite {
  font-style: normal;
  font-size: 0.85em;
  color: var(--muted);
  font-family: var(--serif);
}

/* ---------- Portrait ---------- */
.portrait {
  float: right;
  width: 160px;
  height: 160px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0.25em 0 1em 1.5em;
  border: 1px solid var(--rule);
  box-shadow: 0 2px 6px rgba(0,0,0,0.08);
  shape-outside: circle(50%);
}
@media (max-width: 560px) {
  .portrait {
    float: none;
    display: block;
    margin: 0 auto 1.25em;
    width: 140px;
    height: 140px;
    shape-outside: none;
  }
}

/* ---------- Lede & drop cap ---------- */
.lede { font-size: 1em; }
.dropcap {
  float: left;
  font-family: var(--serif);
  font-weight: 700;
  font-size: 3.5em;
  line-height: 0.85;
  padding: 0.2rem 0.4rem 0 0;
  color: var(--ink);
}

/* ---------- Lists ---------- */
.pretty-list { padding-left: 1.25rem; }
.pretty-list li { margin: 0.5rem 0; }

ul, ol { padding-left: 1.25rem; }
li { margin: 0.25rem 0; }

/* ---------- Timeline (education) ---------- */
.timeline {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.5rem 1.5rem;
  margin: 1rem 0;
}
.timeline dt {
  font-family: var(--sans);
  color: var(--muted);
  font-size: 0.9rem;
  white-space: nowrap;
  padding-top: 0.15rem;
}
.timeline dd { margin: 0; }

/* ---------- Tags ---------- */
.tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.tag {
  background: var(--tag-bg);
  color: var(--ink-soft);
  font-family: var(--sans);
  font-size: 0.82rem;
  padding: 0.18rem 0.6rem;
  border-radius: 999px;
  border: 1px solid transparent;
}

/* ---------- Experience roles ---------- */
.role {
  margin: 1.75rem 0;
  padding-bottom: 0.5rem;
}
.role-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.5rem;
}
.role h3 { margin: 0; }
.role .when {
  font-family: var(--sans);
  color: var(--muted);
  font-size: 0.88rem;
  white-space: nowrap;
}
.role .where {
  color: var(--ink-soft);
  font-style: italic;
  font-size: 0.95rem;
  margin: 0.1rem 0 0.5rem;
}

/* ---------- Projects ---------- */
.project {
  margin: 1.5rem 0;
  padding: 1rem 1.25rem;
  background: var(--bg-elev);
  border: 1px solid var(--rule);
  border-radius: 6px;
}
.project h3 { margin-top: 0; }
.project .meta {
  font-family: var(--sans);
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 0.5rem;
}

/* ---------- Publications ---------- */
.pubs {
  padding-left: 1.25rem;
}
.pubs li {
  margin: 0.75rem 0;
  font-size: 0.98rem;
  line-height: 1.55;
}
.pubs em {
  font-style: italic;
  color: var(--ink);
}
.pubs .doi {
  display: inline-block;
  margin-left: 0.25rem;
  font-family: var(--sans);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 0.05rem 0.5rem;
  background: var(--tag-bg);
  border-radius: 4px;
  border-bottom: none;
}
.pubs .doi:hover {
  background: var(--accent);
  color: var(--bg);
}

/* ---------- Contact list ---------- */
.contact-list {
  list-style: none;
  padding: 0;
  margin: 1rem 0;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}
.contact-list li { margin: 0; }
.contact-list a {
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
  padding: 0.25rem 0;
  text-decoration: none;
  border-bottom: none;
  color: var(--ink);
}
.contact-list a:hover { color: var(--accent-hover); }
.contact-list a:hover .icon { color: var(--accent-hover); }
.contact-list .icon {
  width: 1.1em;
  height: 1.1em;
  flex-shrink: 0;
  color: var(--ink-soft);
  transition: color 0.15s ease;
}

/* ---------- Utility ---------- */
.muted { color: var(--muted); }

/* ---------- Footer ---------- */
.page-footer {
  margin-top: 4rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  color: var(--muted);
  font-size: 0.82rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 960px) {
  .container {
    grid-template-columns: 1fr;
    gap: 1.5rem;
    padding: 2rem 1.25rem 3rem;
  }
  .toc {
    position: static;
    max-height: none;
    border: 1px solid var(--rule);
    border-radius: 6px;
    padding: 1rem 1.25rem;
    background: var(--bg-elev);
  }
  .toc ol { border-left: none; }
  .toc a { padding-left: 0; border-left: none; }
  .toc a.active { border-left: none; }
}
@media (max-width: 560px) {
  body { font-size: 17px; }
  .nav-links { gap: 0.85rem; }
  .nav-links a { font-size: 0.85rem; }
  .nav-links a[href="#experience"],
  .nav-links a[href="#projects"] { display: none; }
  .page-title { font-size: 2rem; }
  .prose h2 { font-size: 1.4rem; }
  .role-head { flex-direction: column; gap: 0.15rem; }
}