/* ==========================================================================
   Haoyu Wu — personal academic site
   Design: "Working Paper" — the site as one continuously-numbered manuscript.
   Single serif type system + mono for structural/meta text. One accent color.
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=STIX+Two+Text:ital,wght@0,400;0,500;0,600;1,400&display=swap');

:root {
  --bg: #FAF8F3;
  --surface: #FFFFFF;
  --text: #1C1B19;
  --muted: #6B6558;
  --accent: #7A1F2B;
  --border: #DDD6C7;

  --serif: 'STIX Two Text', Georgia, 'Times New Roman', ui-serif, serif;
  --mono: ui-monospace, 'SF Mono', Menlo, Consolas, 'Liberation Mono', monospace;

  --measure: 860px;
  --nav-h: 56px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #171510;
    --surface: #1E1B15;
    --text: #EDE8DC;
    --muted: #9C9484;
    --accent: #E2A0A0;
    --border: #332E24;
  }
}

:root[data-theme="dark"] {
  --bg: #171510;
  --surface: #1E1B15;
  --text: #EDE8DC;
  --muted: #9C9484;
  --accent: #E2A0A0;
  --border: #332E24;
}

:root[data-theme="light"] {
  --bg: #FAF8F3;
  --surface: #FFFFFF;
  --text: #1C1B19;
  --muted: #6B6558;
  --accent: #7A1F2B;
  --border: #DDD6C7;
}

/* ---- reset & base ---- */

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

html {
  -webkit-text-size-adjust: 100%;
  background: var(--bg);
  /* Root font-size — every rem-sized element on the site (headings, labels,
     badges, nav, etc.) scales off this one number. Bump it to change the
     overall text size site-wide. */
  font-size: 19px;
}

body {
  margin: 0;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text);
  font-family: var(--serif);
  line-height: 1.65;
  transition: background 0.2s ease, color 0.2s ease;
}

main { flex: 1; }

h1, h2, h3 { font-weight: 600; line-height: 1.25; margin: 0 0 0.6em; }
p { margin: 0 0 1.1em; }
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }

::selection { background: var(--accent); color: var(--surface); }

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

/* small-caps-style label, used for "ABSTRACT", eyebrow lines, etc. */
.label {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
}

.rule {
  border: none;
  border-top: 1px solid var(--border);
  margin: 1.6em 0;
}

.rule--double {
  height: 0;
  margin: 1.4em 0 1.8em;
  border-top: 2px solid var(--accent);
  position: relative;
}
.rule--double::after {
  content: "";
  display: block;
  border-top: 1px solid var(--border);
  margin-top: 3px;
}

/* ---- layout shell ---- */

.wrap {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 0 24px;
}

main { padding-bottom: 4rem; }

/* ---- nav / masthead ---- */

header.masthead {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  background-image: radial-gradient(currentColor 0.6px, transparent 0.6px);
  background-size: 14px 14px;
  background-position: 0 0;
}
header.masthead::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--surface);
  opacity: 0.94;
  z-index: -1;
}
header.masthead.is-scrolled {
  backdrop-filter: blur(8px);
}
header.masthead.is-scrolled::before { opacity: 0.86; }

.masthead__inner {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 0 24px;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}

.masthead__name {
  font-family: var(--mono);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
  text-decoration: none;
  color: var(--text);
  font-weight: 600;
  white-space: nowrap;
}

nav.toc {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.02em;
}
nav.toc a {
  color: var(--muted);
  text-decoration: none;
  padding: 2px 1px;
}
nav.toc a:hover { color: var(--accent); }
nav.toc a.current {
  color: var(--text);
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-underline-offset: 4px;
}
nav.toc .divider { color: var(--border); }

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  border-radius: 4px;
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  line-height: 1;
}
.theme-toggle:hover { color: var(--accent); border-color: var(--accent); }
.theme-toggle svg { width: 15px; height: 15px; }
.theme-toggle .icon-moon { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-moon { display: inline-flex; }

/* ---- title page / hero (index only) ---- */

.titlepage { padding: 3rem 0 1rem; animation: fade-in 0.4s ease both; }
.titlepage .eyebrow { margin-bottom: 0.9rem; }
.titlepage h1 { font-size: 2.3rem; letter-spacing: -0.01em; }

@keyframes fade-in {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

.abstract { display: flex; gap: 0.9rem; align-items: baseline; margin-bottom: 0.5em; }
.abstract .label { flex: none; }

/* ---- title page layout with portrait column ---- */

.titlepage__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.6rem;
}

@media (min-width: 900px) {
  .titlepage__grid {
    grid-template-columns: 1fr 180px;
    column-gap: 2.5rem;
    align-items: start;
  }
  .titlepage__grid > .portrait { order: 2; }
}

.portrait {
  aspect-ratio: 4 / 5;
  width: 100%;
  max-width: 180px;
  border: 1px dashed var(--border);
  border-radius: 2px;
  background: var(--surface);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.3em;
  padding: 1rem;
  text-align: center;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.portrait:has(img) {
  border-style: solid;
  padding: 0;
}
.portrait img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 1px;
}

/* ---- generic page header (non-index pages) ---- */

.pagehead { padding: 2.4rem 0 0.4rem; }
.pagehead .eyebrow { margin-bottom: 0.6rem; }
.pagehead h1 { font-size: 1.7rem; }
.pagehead .dek { color: var(--muted); font-size: 0.95rem; margin-top: -0.3em; }

/* ---- research entries: citation block (left) + abstract (right) ---- */

.entry {
  padding: 1.6rem 0;
  border-top: 1px solid var(--border);
}
.entry:first-of-type { border-top: none; }

.entry__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}

@media (min-width: 900px) {
  .entry__grid {
    grid-template-columns: 280px 1fr;
    column-gap: 2.5rem;
    align-items: start;
  }
}

.entry__title { font-size: 1.05rem; font-weight: 600; margin-bottom: 0.3em; }

.entry__authors {
  font-size: 0.92rem;
  color: var(--muted);
  margin: 0 0 0.6em;
}

.entry__meta {
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0.5em 0 0.7em;
}

.entry__venue {
  font-size: 0.85rem;
  font-style: italic;
  color: var(--text);
  margin: 0.6em 0 0.5em;
}

.entry__links a {
  font-family: var(--mono);
  font-size: 0.8rem;
  margin-right: 1.1em;
  white-space: nowrap;
}
.entry__links a::before { content: "[ "; color: var(--muted); }
.entry__links a::after { content: " ]"; color: var(--muted); }

.entry__abstract .label { display: block; margin-bottom: 0.5em; }
.entry__abstract p {
  font-size: 0.95rem;
  color: var(--text);
  margin: 0;
}

.placeholder-entry {
  border-top: 1px dashed var(--border);
  padding: 1.4rem 0;
  color: var(--muted);
  font-size: 0.9rem;
}
.placeholder-entry .label { display: block; margin-bottom: 0.4em; }

/* ---- publication tag badge (used inline in entry titles) ---- */

.bib-tag {
  display: inline-block;
  font-family: var(--mono);
  font-weight: 400;
  font-size: 0.68rem;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 3px;
  padding: 0.05em 0.4em;
  margin-right: 0.6em;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  vertical-align: middle;
}

/* ---- CV / vita ---- */

.vita dt {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--muted);
  float: left;
  width: 6.5em;
  clear: left;
  padding-top: 0.15em;
}
.vita dd {
  margin: 0 0 1.1em 6.5em;
}
.fill-blank {
  color: var(--muted);
  border-bottom: 1px dashed var(--muted);
}

.subsection { margin-top: 2.2rem; }
.subsection h2 {
  font-size: 1.05rem;
  font-family: var(--mono);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.4em;
  margin-bottom: 1em;
}
.subsection ul { padding-left: 1.2em; margin: 0; }
.subsection li { margin-bottom: 0.6em; }

.cv-download {
  display: inline-block;
  margin-top: 0.6em;
  font-family: var(--mono);
  font-size: 0.85rem;
}
.cv-download::before { content: "[ "; color: var(--muted); }
.cv-download::after { content: " ]"; color: var(--muted); }

/* ---- talks & posters, listed under a research entry's abstract ---- */

.entry__talks { margin-top: 1.4rem; }
.entry__talks .talk-list {
  list-style: none;
  padding: 0;
  margin: 0 0 1.2rem;
}
.entry__talks .talk-list:last-child { margin-bottom: 0; }
.entry__talks .talk-list li {
  border-left: 2px solid var(--border);
  padding: 0.1rem 0 0.1rem 0.9rem;
  margin-bottom: 0.9rem;
}
.entry__talks .talk__event { font-size: 0.92rem; font-style: italic; }
.entry__talks .bib-tag { font-style: normal; }
.entry__talks .talk__meta {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0.15em 0 0.45em;
}
.entry__talks .talk-list li > :last-child { margin-bottom: 0; }

/* ---- notes page ---- */

.notes-list { padding-left: 1.2em; }
.notes-list li { margin-bottom: 0.5em; }

.notes-callout {
  border-left: 2px solid var(--accent);
  padding: 0.2em 0 0.2em 1rem;
  margin: 1.6em 0;
  color: var(--muted);
  font-style: italic;
  font-size: 0.95rem;
}

/* ---- visitor map (small block in the home-page footer) ---- */

.footer-grid {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1.5rem 3rem;
  flex-wrap: wrap;
}

.visitors { width: 300px; max-width: 100%; }

.visitor-toggle {
  font-family: var(--mono);
  font-size: 0.7rem;
  letter-spacing: 0.02em;
  margin-bottom: 0.35rem;
}
.visitor-toggle button {
  background: none;
  border: none;
  padding: 2px 1px;
  cursor: pointer;
  font: inherit;
  color: var(--muted);
}
.visitor-toggle button:hover { color: var(--accent); }
.visitor-toggle button[aria-pressed="true"] {
  color: var(--text);
  text-decoration: underline;
  text-decoration-color: var(--accent);
  text-underline-offset: 4px;
}
.visitor-toggle .divider { color: var(--border); }

.visitor-map svg { display: block; width: 100%; height: auto; }
.visitor-map .land {
  fill: none;
  stroke: var(--border);
  stroke-width: 3;
  stroke-linecap: round;
}
.visitor-map .vdot {
  fill: var(--accent);
  fill-opacity: 0.7;
  stroke: var(--accent);
  stroke-width: 0.6;
  stroke-opacity: 0.9;
}

#visitor-stats { margin: 0.35rem 0 0; font-size: 0.65rem; }

/* ---- footer ---- */

footer.colophon {
  border-top: 1px solid var(--border);
  margin-top: 2rem;
  padding: 1.6rem 0 3rem;
  background-image: radial-gradient(currentColor 0.6px, transparent 0.6px);
  background-size: 14px 14px;
}
footer.colophon .contact { margin: 0; font-size: 0.85rem; }
footer.colophon .contact a { color: var(--muted); }

/* ---- misc ---- */

.hide-js { display: none; }
.js .hide-js { display: inline-flex; }

/* phones: the nav drops below the name, so let the masthead grow to fit
   instead of spilling over the page */
@media (max-width: 600px) {
  .masthead__inner {
    height: auto;
    min-height: var(--nav-h);
    padding-top: 10px;
    padding-bottom: 10px;
    row-gap: 6px;
  }
  nav.toc { gap: 0.3rem; font-size: 0.7rem; }
}

@media (max-width: 480px) {
  .titlepage h1 { font-size: 1.9rem; }
  .abstract { flex-direction: column; gap: 0.2rem; }
}