/* ============================================================
   Alan Xu — personal site
   ============================================================ */

:root {
  --paper:      #F4F7FA;
  --ink:        #1C2321;
  --water:      #1A5C8A;   /* darkened Carolina blue — for links and small text */
  --carolina:   #4B9CD3;   /* true Carolina blue — large text and accents only */
  --muted:      #6E7A72;
  --rule:       #CBDCE8;   /* faint Carolina tint for hairlines */

  --serif: "Iowan Old Style", "Charter", "Palatino Linotype", Palatino,
           Georgia, "Songti SC", "SimSun", serif;
  --han:   "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
           "Source Han Sans SC", "Noto Sans CJK SC", sans-serif;
  --sans:  system-ui, -apple-system, "Segoe UI", Roboto,
           "Helvetica Neue", Arial, sans-serif;

  --measure: 62ch;
}

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

html { font-size: 18px; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  padding: 0 1.5rem 6rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1rem;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.page { max-width: 54rem; margin: 0 auto; }

/* ---------- links ---------- */

a {
  color: var(--water);
  text-decoration: none;
  border-bottom: 1px solid rgba(31, 78, 95, 0.3);
}
a:hover { border-bottom-color: var(--water); }
a:focus-visible {
  outline: 2px solid var(--water);
  outline-offset: 3px;
  border-radius: 1px;
}

.skip {
  position: absolute;
  left: -9999px;
}
.skip:focus {
  left: 1.5rem;
  top: 1rem;
  background: var(--ink);
  color: var(--paper);
  padding: 0.5rem 0.9rem;
  border: 0;
  z-index: 10;
}

/* ---------- header + nav ---------- */

.masthead {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.75rem 2rem;
  padding: 2.25rem 0 0;
}

.wordmark {
  font-size: 1.0625rem;
  color: var(--ink);
  border-bottom: 0;
  white-space: nowrap;
}
.wordmark .han { font-family: var(--han); margin-left: 0.4em; color: var(--water); }
.wordmark:hover { color: var(--water); }

.nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0 1.5rem;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--sans);
  font-size: 0.8125rem;
  letter-spacing: 0.01em;
}
.nav a {
  color: var(--muted);
  border-bottom: 0;
  padding-bottom: 2px;
}
.nav a:hover { color: var(--ink); }
.nav a[aria-current="page"] {
  color: var(--ink);
  border-bottom: 1px solid var(--ink);
}

/* ---------- page title (interior pages) ---------- */

.page-title {
  margin: 3.5rem 0 2.5rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--rule);
  font-weight: 400;
  font-size: 2.125rem;
  letter-spacing: -0.015em;
}

/* ---------- the rail layout ---------- */

.band {
  display: grid;
  grid-template-columns: 9rem 1fr;
  gap: 0 2.75rem;
  padding: 2.75rem 0;
  border-top: 1px solid var(--rule);
}
.band:first-of-type { border-top: 0; }

.band > h2 {
  margin: 0;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 600;
  line-height: 1.9;
  color: var(--muted);
  letter-spacing: 0.02em;
}

.band-body > *:first-child { margin-top: 0; }
.band-body > *:last-child  { margin-bottom: 0; }
.band-body p { max-width: var(--measure); margin: 0 0 1.1em; }

/* ---------- publications ---------- */

.pubs { margin: 0; padding: 0; list-style: none; }

.pub {
  display: grid;
  grid-template-columns: 3.25rem 1fr;
  gap: 0 1.25rem;
  margin-bottom: 1.9rem;
}
.pub:last-child { margin-bottom: 0; }

.pub .year {
  font-family: var(--sans);
  font-size: 0.8125rem;
  color: var(--muted);
  line-height: 1.9;
  font-variant-numeric: tabular-nums;
}
.pub .title { display: block; line-height: 1.45; }
.pub .meta {
  display: block;
  margin-top: 0.2em;
  font-size: 0.9375rem;
  color: var(--muted);
}
.pub .venue { font-style: italic; }

/* ---------- projects ---------- */

.projects { margin: 0; padding: 0; list-style: none; }

.project { margin-bottom: 1.9rem; max-width: var(--measure); }
.project:last-child { margin-bottom: 0; }
.project h3 {
  margin: 0 0 0.3em;
  font-size: 1.0625rem;
  font-weight: 600;
  line-height: 1.4;
}
.project p { margin: 0 0 0.4em; }
.project .status {
  font-family: var(--sans);
  font-size: 0.8125rem;
  color: var(--muted);
  line-height: 1.55;
  display: block;
}

/* ---------- courses ---------- */

.courses { margin: 0 0 2rem; padding: 0; list-style: none; }
.courses:last-child { margin-bottom: 0; }

.course {
  display: grid;
  grid-template-columns: 7.5rem 1fr;
  gap: 0 1.25rem;
  margin-bottom: 0.85rem;
}
.course .code {
  font-family: var(--sans);
  font-size: 0.8125rem;
  color: var(--muted);
  line-height: 1.9;
}
.course .name { line-height: 1.45; }
.course .where { color: var(--muted); font-size: 0.9375rem; }

.subhead {
  margin: 2.25rem 0 0.9rem;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--ink);
}
.subhead:first-child { margin-top: 0; }

/* ---------- student comments ---------- */

.comments { margin: 0; padding: 0; list-style: none; max-width: var(--measure); }
.comments li {
  margin-bottom: 1.4rem;
  padding-left: 1.25rem;
  border-left: 2px solid var(--rule);
  font-size: 0.9375rem;
  line-height: 1.65;
  color: var(--ink);
}
.comments li:last-child { margin-bottom: 0; }

/* ---------- coauthors ---------- */

.people { margin: 0; padding: 0; list-style: none; }
.people li { margin-bottom: 0.55rem; line-height: 1.45; }
.people .affil { color: var(--muted); font-size: 0.9375rem; }

/* ---------- contact / elsewhere lists ---------- */

.stack { margin: 0; padding: 0; list-style: none; }
.stack li { margin-bottom: 0.5rem; line-height: 1.5; }
.stack .note {
  font-family: var(--sans);
  font-size: 0.75rem;
  color: var(--muted);
  margin-left: 0.5em;
}

/* ---------- figures ---------- */

figure { margin: 0 0 2.5rem; max-width: var(--measure); }
figure:last-child { margin-bottom: 0; }
figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--rule);
}
figcaption {
  margin-top: 0.7rem;
  font-size: 0.9375rem;
  line-height: 1.55;
  color: var(--muted);
}

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

.foot {
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.75rem;
  color: var(--muted);
}
.foot a { color: var(--muted); border-bottom-color: var(--rule); }
.foot a:hover { color: var(--ink); }

/* ---------- narrow screens ---------- */

@media (max-width: 46rem) {
  html { font-size: 17px; }
  body { padding-left: 1.25rem; padding-right: 1.25rem; }

  .band {
    grid-template-columns: 1fr;
    gap: 0;
    padding: 2.25rem 0;
  }
  .band > h2 { margin-bottom: 1rem; }

  .lockup { padding: 3rem 0 2.25rem; }
  .course { grid-template-columns: 1fr; gap: 0; }
  .course .code { line-height: 1.5; }
}

/* ---------- accessibility + print ---------- */

@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
}

@media print {
  body { background: #fff; padding: 0; font-size: 11pt; }
  .nav, .skip, .foot { display: none; }
  a { color: inherit; border-bottom: 0; }
  .band { break-inside: avoid; border-top: 1px solid #ccc; }
}

/* ---------- Carolina blue accents ---------- */

.lockup .han        { color: var(--carolina); }
.slide-dot.is-active { background: var(--carolina); border-color: var(--carolina); }
.page-title         { border-bottom-color: var(--carolina); }


/* ---------- embedded CV ---------- */

.pdf-frame {
  display: block;
  width: 100%;
  height: 85vh;
  min-height: 36rem;
  margin-top: 1.25rem;
  border: 1px solid var(--rule);
  background: #fff;
}

@media (max-width: 46rem) {
  .pdf-frame { display: none; }
}

/* ---------- slideshow ---------- */

.slideshow { max-width: var(--measure); }

.slides {
  position: relative;
  aspect-ratio: 3 / 2;
  overflow: hidden;
  border: 1px solid var(--rule);
  background: var(--rule);
}

.slide {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
  transition: opacity 700ms ease;
}
.slide.is-active { opacity: 1; }

.slide-dots { display: flex; gap: 0.5rem; margin-top: 0.75rem; }

.slide-dot {
  width: 0.5rem;
  height: 0.5rem;
  padding: 0;
  border: 1px solid var(--muted);
  border-radius: 50%;
  background: transparent;
  cursor: pointer;
}
.slide-dot.is-active { background: var(--water); border-color: var(--water); }
.slide-dot:focus-visible { outline: 2px solid var(--water); outline-offset: 3px; }

/* ---------- academicpages-style profile layout ---------- */

.profile-layout {
  display: grid;
  grid-template-columns: 15rem 1fr;
  gap: 0 3.5rem;
  padding-top: 3.5rem;
  align-items: start;
}

.profile-card { position: sticky; top: 2.5rem; }

.profile-photo {
  display: block;
  width: 100%;
  aspect-ratio: 4 / 5;
  object-fit: cover;
  border: 1px solid var(--rule);
  margin-bottom: 1.25rem;
}

.profile-name {
  margin: 0;
  font-weight: 400;
  font-size: 1.75rem;
  line-height: 1.15;
  letter-spacing: -0.015em;
}
.profile-name .han {
  display: block;
  font-family: var(--han);
  font-size: 1.125rem;
  letter-spacing: 0.14em;
  color: var(--carolina);
  margin-top: 0.35em;
}

.profile-role {
  margin: 0.75rem 0 1.5rem;
  font-size: 0.9375rem;
  line-height: 1.45;
  color: var(--muted);
}

.profile-links {
  margin: 0;
  padding: 1.25rem 0 0;
  list-style: none;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.875rem;
}
.profile-links li {
  display: grid;
  grid-template-columns: 1.5em 1fr;
  align-items: start;
  margin-bottom: 0.7rem;
  line-height: 1.45;
  color: var(--muted);
}
.profile-links svg {
  width: 1em;
  height: 1em;
  margin-top: 0.2em;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.75;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.profile-links a { border-bottom: 0; }
.profile-links a:hover { border-bottom: 1px solid var(--water); }

.profile-links svg.brand {
  fill: currentColor;
  stroke: none;
}

.profile-main > *:first-child { margin-top: 0; }
.profile-main p { max-width: var(--measure); margin: 0 0 1.15em; }

.profile-main .lede {
  font-size: 1.4375rem;
  line-height: 1.45;
  font-style: italic;
  color: var(--water);
  max-width: 38ch;
  margin-bottom: 2rem;
}

.profile-main h2 {
  margin: 2.5rem 0 0.9rem;
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--muted);
  letter-spacing: 0.02em;
}

@media (max-width: 46rem) {
  .profile-layout { grid-template-columns: 1fr; gap: 2.5rem 0; padding-top: 2.25rem; }
  .profile-card { position: static; }
  .profile-photo { width: 9rem; }
}

.pubs-status .pub { grid-template-columns: 5.5rem 1fr; }