/* ------------------------------------------------------------------
   Wang Bill Zhu — personal site
   A single, deliberately simple stylesheet. No frameworks.
   ------------------------------------------------------------------ */

:root {
  --bg:        #fbfaf6;
  --surface:   #ffffff;
  --ink:       #1f2024;
  --ink-soft:  #4b4d55;
  --ink-mute:  #7a7c84;
  --rule:      #e7e3d8;
  --accent:    #8a3324;          /* warm crimson */
  --accent-soft: #c87a6b;
  --tag-bg:    #f1ede2;
  --tag-ink:   #5a4634;
  --max-width: 1080px;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: "Source Serif 4", "Source Serif Pro", "Iowan Old Style",
               "Apple Garamond", Georgia, "Times New Roman", serif;
  font-size: 18px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s ease, color 0.15s ease;
}
a:hover { border-bottom-color: var(--accent); }

.wrap {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 56px 28px 80px;
}

/* ---------- Hero / header ---------- */

.hero {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: 40px;
  align-items: start;
}

.portrait img {
  width: 200px;
  height: 200px;
  object-fit: cover;
  border-radius: 50%;
  display: block;
  box-shadow: 0 1px 0 rgba(0,0,0,0.04), 0 8px 28px rgba(50,40,30,0.10);
}

.socials {
  display: flex;
  gap: 16px;
  margin-top: 14px;
  justify-content: center;
  align-items: center;
  flex-wrap: nowrap;
}
.socials a {
  border-bottom: none;
  display: inline-flex;
  align-items: center; justify-content: center;
  font-size: 22px;
  line-height: 1;
  transition: transform 0.12s ease, filter 0.15s ease;
}
.socials a:hover { transform: translateY(-1px); filter: brightness(1.05); border-bottom: none; }

/* Each platform gets its canonical brand color so the row reads like a
   row of recognizable logos rather than uniform grey glyphs. */
.socials .s-email    { color: #d44638; }   /* Gmail red          */
.socials .s-cv       { color: #2a5d6e; }   /* document teal      */
.socials .s-scholar  { color: #4285f4; }   /* Google blue        */
.socials .s-github   { color: #181717; }   /* GitHub near-black  */
.socials .s-x        { color: #000000; }   /* X / Twitter black  */
.socials .s-linkedin { color: #0a66c2; }   /* LinkedIn blue      */

.intro h1 {
  font-family: inherit;
  font-weight: 600;
  font-size: 2.1rem;
  letter-spacing: -0.01em;
  margin: 0 0 0.2rem;
}
.intro .role {
  margin: 0 0 1rem;
  color: var(--ink-mute);
  font-size: 1.02rem;
  font-style: italic;
}
.intro p { margin: 0 0 0.9rem; color: var(--ink-soft); }
.intro ul.research-directions {
  margin: -0.4rem 0 0.9rem;
  padding-left: 1.25rem;
  color: var(--ink-soft);
}
.intro ul.research-directions li { margin-bottom: 0.4rem; }

/* ---------- Section structure ---------- */

section { margin-top: 64px; }

h2.section-title {
  font-family: inherit;
  font-weight: 600;
  font-size: 1.7rem;
  letter-spacing: -0.01em;
  margin: 0 0 1.5rem;
  padding-bottom: 0.55rem;
  color: var(--ink);
  position: relative;
  border-bottom: 1px solid var(--rule);
}
/* A short coloured underline sits on top of the thin grey rule, so each
   section heading reads as the start of a clearly demarcated block. */
h2.section-title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 64px;
  height: 3px;
  background: var(--accent);
  border-radius: 2px;
}

/* ---------- News ---------- */

.news-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 0.6rem;
}
.news-list li {
  display: grid;
  grid-template-columns: 100px 1fr;
  gap: 18px;
  align-items: baseline;
}
.news-date {
  color: var(--ink-mute);
  font-size: 0.92rem;
  font-variant-numeric: tabular-nums;
}
.news-body { color: var(--ink-soft); }
.news-body strong { color: var(--ink); font-weight: 600; }

/* ---------- Publications ---------- */

.tabs {
  display: flex;
  gap: 4px;
  margin-bottom: 1.5rem;
  border-bottom: 1px solid var(--rule);
  flex-wrap: wrap;
}
.tab {
  appearance: none;
  background: none;
  border: none;
  padding: 10px 16px;
  font: inherit;
  font-size: 0.98rem;
  color: var(--ink-mute);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -1px;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.tab:hover { color: var(--ink); }
.tab.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

/* Sub-tab chip row inside taxonomy views ---------------------------- */
.chips {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 1.4rem;
}
.chip {
  appearance: none;
  border: 1px solid var(--rule);
  background: var(--surface);
  color: var(--ink-soft);
  font: inherit;
  font-size: 0.86rem;
  padding: 5px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.chip:hover { color: var(--accent); border-color: var(--accent-soft); }
.chip.active {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.pub-empty {
  color: var(--ink-mute);
  font-style: italic;
  margin: 1rem 0;
}

/* Category labels (when "All" is selected and groups appear) ------- */
/* Visually distinct from paper titles: small caps, sans-serif feel,
   colored block to the left, sits in its own row.                    */
.pub-group { margin-top: 1.6rem; }
.pub-group:first-child { margin-top: 0; }
.pub-group-title {
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI",
               Helvetica, Arial, sans-serif;
  font-weight: 600;
  font-size: 0.78rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 0.6rem;
  padding: 0.35rem 0.8rem;
  display: inline-block;
  background: var(--tag-bg);
  border-left: 3px solid var(--accent);
  border-radius: 2px;
}
.pub-group:first-child .pub-group-title { margin-top: 0; }

.pub-list { list-style: none; padding: 0; margin: 0; }
.pub-list li { padding: 0.7rem 0; border-bottom: 1px dashed var(--rule); }
.pub-list li:last-child { border-bottom: none; }

.pub-title { font-weight: 600; color: var(--ink); }
.pub-authors { color: var(--ink-soft); font-size: 0.97rem; }
.pub-authors .me {
  font-weight: 600;
  color: var(--ink);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}
.pub-venue { color: var(--ink-mute); font-style: italic; font-size: 0.95rem; }
/* Award marker — bright magenta, plain text, no highlighter or box.
   High contrast against the cream background and clearly distinct from
   the page's crimson accent so spotlights jump out at a glance. */
.pub-award {
  display: inline-block;
  margin-left: 0.4rem;
  color: #db2777;
  font-style: normal;
  font-weight: 800;
  font-size: 0.92rem;
  letter-spacing: 0.01em;
}
.pub-award::before { content: "["; }
.pub-award::after  { content: "]"; }

/* News-item marker — plain bold text wrapped in brackets, no color or
   uppercase tricks. Stays unobtrusive but signals "this is a tag." */
.news-tag {
  font-weight: 700;
  color: var(--ink);
}

.pub-actions {
  margin-top: 0.3rem;
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
  align-items: center;
}
.pub-link, .bib-toggle {
  font: inherit;
  font-size: 0.85rem;
  padding: 2px 10px;
  border: 1px solid var(--rule);
  border-radius: 4px;
  color: var(--ink-soft);
  background: var(--surface);
  cursor: pointer;
  border-bottom: 1px solid var(--rule);
  text-decoration: none;
}
.pub-link:hover, .bib-toggle:hover {
  color: var(--accent);
  border-color: var(--accent-soft);
}
.bib-toggle.active {
  color: #fff;
  background: var(--accent);
  border-color: var(--accent);
}
.bib-block {
  width: 100%;
  margin: 0.45rem 0 0;
  padding: 0.75rem 1rem;
  background: #faf6ec;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--accent-soft);
  border-radius: 4px;
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.78rem;
  line-height: 1.5;
  color: var(--ink-soft);
  overflow-x: auto;
  white-space: pre;
}
.bib-block[hidden] { display: none; }

.pub-tags {
  margin-top: 0.35rem;
  display: flex;
  gap: 0.3rem;
  flex-wrap: wrap;
}
.pub-tag {
  font-size: 0.78rem;
  padding: 2px 9px;
  border-radius: 999px;
  background: var(--tag-bg);
  color: var(--tag-ink);
  font-style: normal;
}

/* ---------- Footer ---------- */

footer {
  margin-top: 96px;
  padding-top: 24px;
  border-top: 1px solid var(--rule);
  color: var(--ink-mute);
  font-size: 0.88rem;
  text-align: center;
}

/* ---------- Work-with-me page ---------- */

.subpage h1 {
  font-weight: 600;
  font-size: 2rem;
  margin: 0 0 0.4rem;
}
.subpage .lede {
  color: var(--ink-mute);
  font-style: italic;
  margin: 0 0 2rem;
}
.callout {
  background: var(--surface);
  border-left: 4px solid var(--accent);
  padding: 1.1rem 1.3rem;
  margin: 1.5rem 0;
  border-radius: 4px;
  box-shadow: 0 1px 2px rgba(0,0,0,0.03);
}
.callout strong { color: var(--accent); }

.subpage h2 {
  font-weight: 600;
  font-size: 1.3rem;
  margin: 2rem 0 0.8rem;
}
.subpage ul { padding-left: 1.2rem; }
.subpage li { margin-bottom: 0.5rem; color: var(--ink-soft); }

.back-link {
  display: inline-block;
  margin-bottom: 1.5rem;
  font-size: 0.95rem;
  color: var(--ink-mute);
  border-bottom: none;
}
.back-link:hover { color: var(--accent); border-bottom: none; }

/* ---------- Responsive ---------- */

/* Tablet & narrow laptop — relax the wide hero into something less airy. */
@media (max-width: 900px) {
  .wrap { padding: 48px 24px 72px; }
}

/* Phones — collapse hero into a single centered column. */
@media (max-width: 640px) {
  body { font-size: 17px; }
  .wrap { padding: 36px 20px 60px; }
  .hero { grid-template-columns: 1fr; gap: 24px; }
  .portrait { display: flex; flex-direction: column; align-items: center; }
  .portrait img { width: 160px; height: 160px; }
  .socials { margin-top: 14px; gap: 14px; }
  .news-list li { grid-template-columns: 1fr; gap: 2px; }
  .news-date { font-size: 0.85rem; }
  .intro h1 { font-size: 1.7rem; }
  h2.section-title { font-size: 1.4rem; }
  .bib-block { font-size: 0.72rem; }
}