/* ─────────────────────────────────────────────
   Wanjiang Jacob Zhang · jacobzwj.com
   Editorial system: warm paper, ink, Prussian blue.
   Set in Fraunces (display) & Inter (text).
   ───────────────────────────────────────────── */

@font-face {
  font-family: "Fraunces";
  src: url("assets/fonts/fraunces.woff2") format("woff2");
  font-weight: 300 700;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Fraunces";
  src: url("assets/fonts/fraunces-italic.woff2") format("woff2");
  font-weight: 300 700;
  font-style: italic;
  font-display: swap;
}
@font-face {
  font-family: "Inter";
  src: url("assets/fonts/inter.woff2") format("woff2");
  font-weight: 300 700;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: "Inter";
  src: url("assets/fonts/inter-italic.woff2") format("woff2");
  font-weight: 300 700;
  font-style: italic;
  font-display: swap;
}

:root {
  --paper: #f6f3ec;
  --paper-deep: #efeadf;
  --ink: #191712;
  --ink-soft: #3c3830;
  --muted: #6d675a;
  --line: #ddd6c6;
  --line-soft: #e7e1d3;
  --accent: #1f3d5c;
  --accent-soft: #48627e;
  --serif: "Fraunces", "Songti SC", "SimSun", Georgia, serif;
  --sans: "Inter", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --cjk-serif: "Songti SC", "STSong", "SimSun", serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 5.5rem; }

body {
  font-family: var(--sans);
  font-optical-sizing: auto;
  font-size: 16.5px;
  line-height: 1.68;
  color: var(--ink);
  background-color: var(--paper);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='240' height='240'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 0.35 0 0 0 0 0.33 0 0 0 0 0.28 0 0 0 0.045 0'/%3E%3C/filter%3E%3Crect width='240' height='240' filter='url(%23n)'/%3E%3C/svg%3E");
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

::selection { background: rgba(31, 61, 92, .18); }

.wrap {
  max-width: 1180px;
  margin-inline: auto;
  padding-inline: clamp(22px, 5vw, 60px);
}

a { color: inherit; }

/* ── Header ─────────────────────────────── */

.site-head {
  position: sticky;
  top: 0;
  z-index: 20;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid transparent;
  transition: border-color .3s ease;
}
.site-head.scrolled { border-bottom-color: var(--line); }

.head-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 1.05rem;
}

.brand {
  font-family: var(--serif);
  font-weight: 500;
  font-size: 1.02rem;
  letter-spacing: .01em;
  text-decoration: none;
}
.brand-cjk {
  font-family: var(--cjk-serif);
  font-weight: 400;
  color: var(--muted);
  margin-left: .45em;
  font-size: .92em;
}

.site-nav {
  display: flex;
  gap: clamp(.9rem, 2.4vw, 1.7rem);
  font-size: .74rem;
  font-weight: 500;
  letter-spacing: .14em;
  text-transform: uppercase;
}
.site-nav a {
  text-decoration: none;
  color: var(--muted);
  padding-block: .2rem;
  border-bottom: 1px solid transparent;
  transition: color .25s ease, border-color .25s ease;
}
.site-nav a:hover { color: var(--ink); }
.site-nav a.active { color: var(--accent); border-bottom-color: var(--accent); }
.site-nav .nav-cv { color: var(--accent); }
.site-nav .nav-cv:hover { border-bottom-color: var(--accent); }

/* ── Hero ───────────────────────────────── */

.hero { padding-block: clamp(3.5rem, 9vh, 7rem) clamp(4rem, 10vh, 7.5rem); }

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, .8fr);
  gap: clamp(2.5rem, 6vw, 5.5rem);
  align-items: center;
}

.kicker {
  font-size: .72rem;
  font-weight: 550;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 1.6rem;
}
.kick-sep { margin-inline: .7em; color: var(--line); }

h1 {
  font-family: var(--serif);
  font-weight: 380;
  font-size: clamp(2.9rem, 6.5vw, 5.1rem);
  line-height: 1.02;
  letter-spacing: -.015em;
  margin-bottom: 1.8rem;
}

.lede {
  font-family: var(--serif);
  font-weight: 350;
  font-size: clamp(1.14rem, 1.9vw, 1.34rem);
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: 34em;
  margin-bottom: 2rem;
}

.hero-links {
  font-size: .95rem;
  display: flex;
  flex-wrap: wrap;
  gap: .65em;
  align-items: baseline;
  margin-bottom: 2.4rem;
}
.hero-links a {
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  padding-bottom: .1em;
  transition: border-color .25s ease, color .25s ease;
}
.hero-links a:hover { color: var(--accent); border-bottom-color: var(--accent); }
.hero-links span { color: var(--line); }

.hero-prov {
  font-size: .84rem;
  line-height: 1.7;
  color: var(--muted);
  padding-top: 1.3rem;
  border-top: 1px solid var(--line);
  max-width: 36em;
}

.hero-photo {
  position: relative;
  justify-self: end;
  width: min(100%, 400px);
}
.hero-photo img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--ink);
}
.hero-photo::after {
  content: "";
  position: absolute;
  inset: 0;
  translate: 16px 16px;
  border: 1px solid var(--line);
  z-index: -1;
}
.cjk-vert {
  position: absolute;
  top: .2rem;
  left: -2.3rem;
  writing-mode: vertical-rl;
  font-family: var(--cjk-serif);
  font-size: .95rem;
  letter-spacing: .55em;
  color: var(--muted);
}

/* ── Sections ───────────────────────────── */

.section { border-top: 1px solid var(--line); padding-block: clamp(3.6rem, 8vh, 6.2rem); }

.section-grid {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: clamp(2rem, 5vw, 4.5rem);
  align-items: start;
}

.section-label {
  position: sticky;
  top: 5.4rem;
  display: flex;
  align-items: baseline;
  gap: .8rem;
}
.sec-no {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 400;
  font-size: 1.05rem;
  color: var(--accent);
}
.sec-name {
  font-size: .74rem;
  font-weight: 550;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--ink-soft);
}

.prose { max-width: 44em; color: var(--ink-soft); }
.prose a { color: var(--accent); text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: .18em; }
.prose a:hover { text-decoration-color: var(--accent); }

.prose-lg {
  font-family: var(--serif);
  font-weight: 350;
  font-size: clamp(1.25rem, 2.2vw, 1.55rem);
  line-height: 1.5;
  max-width: 30em;
  margin-bottom: 2.6rem;
}
.prose-lg em { font-style: italic; color: var(--accent); }

/* Research areas */

.areas {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(1.4rem, 3vw, 2.6rem);
  margin-bottom: 2.6rem;
}
.area { border-top: 1px solid var(--line); padding-top: 1.1rem; }
.area-no {
  font-family: var(--cjk-serif);
  display: block;
  font-size: .95rem;
  color: var(--accent);
  margin-bottom: .7rem;
}
.area h3 {
  font-family: var(--serif);
  font-weight: 500;
  font-size: 1.08rem;
  margin-bottom: .55rem;
  letter-spacing: .002em;
}
.area p { font-size: .92rem; line-height: 1.62; color: var(--muted); }

.edu { margin-top: 2.8rem; }

.mini-head {
  font-size: .72rem;
  font-weight: 550;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: .9rem;
}

.edu-list { list-style: none; max-width: 44em; }
.edu-list li {
  display: flex;
  gap: 1.6rem;
  padding-block: .55rem;
  border-top: 1px solid var(--line-soft);
  font-size: .95rem;
  color: var(--ink-soft);
}
.edu-year {
  font-family: var(--serif);
  font-style: italic;
  color: var(--accent);
  min-width: 3rem;
}

/* Publications */

.note { font-size: .84rem; color: var(--muted); margin-bottom: 2.2rem; }
.ast { color: var(--accent); font-weight: 600; }

.year-group {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr);
  gap: clamp(1rem, 3vw, 2.5rem);
  margin-bottom: .4rem;
}
.year {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 380;
  font-size: 1.7rem;
  color: var(--accent);
  line-height: 1;
  padding-top: 1.45rem;
  position: sticky;
  top: 5.4rem;
}

.pub {
  padding-block: 1.4rem;
  border-top: 1px solid var(--line);
}
.pub h3 {
  font-family: var(--serif);
  font-weight: 450;
  font-size: 1.16rem;
  line-height: 1.42;
  letter-spacing: .002em;
  margin-bottom: .5rem;
  max-width: 40em;
}
.pub h3 a {
  text-decoration: none;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 0% 1px;
  background-repeat: no-repeat;
  background-position: 0 96%;
  transition: background-size .35s ease, color .25s ease;
}
.pub h3 a:hover { color: var(--accent); background-size: 100% 1px; }
.pub .authors { font-size: .9rem; color: var(--muted); margin-bottom: .15rem; }
.pub .authors strong { color: var(--ink); font-weight: 550; }
.pub .meta { font-size: .9rem; color: var(--ink-soft); }
.pub .meta em { font-family: var(--serif); font-size: 1.02em; }
.pub .zh {
  font-family: var(--cjk-serif);
  font-size: .86rem;
  color: var(--muted);
  margin-top: .45rem;
  max-width: 44em;
}

/* Projects */

.feature {
  border: 1px solid var(--line);
  padding: clamp(1.4rem, 3vw, 2.2rem);
  margin-bottom: 2.8rem;
  position: relative;
  background: color-mix(in srgb, var(--paper-deep) 55%, transparent);
}
.feature::before {
  content: "";
  position: absolute;
  top: -1px; left: -1px;
  width: 2.4rem; height: 2.4rem;
  border-top: 2px solid var(--accent);
  border-left: 2px solid var(--accent);
}
.feature-title {
  font-family: var(--serif);
  font-weight: 480;
  font-size: 1.5rem;
  margin-bottom: .7rem;
}
.feature-title a { text-decoration: none; transition: color .25s ease; }
.feature-title a:hover { color: var(--accent); }

.wip { list-style: none; }
.wip li { padding-block: 1.15rem; border-top: 1px solid var(--line-soft); }
.wip-title {
  font-family: var(--serif);
  font-weight: 430;
  font-size: 1.06rem;
  line-height: 1.45;
  max-width: 42em;
  margin-bottom: .25rem;
}
.wip-meta { font-size: .85rem; color: var(--muted); }

/* Teaching */

.teach-cols {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(1.8rem, 4vw, 3.4rem);
}
.teach-cols .mini-head:not(:first-child) { margin-top: 2rem; }
.plain-list { list-style: none; }
.plain-list li {
  font-size: .95rem;
  color: var(--ink-soft);
  padding-block: .5rem;
  border-top: 1px solid var(--line-soft);
  line-height: 1.55;
}
.plain-list em { font-family: var(--serif); }

/* Recognition */

.awards { list-style: none; }
.awards li {
  display: grid;
  grid-template-columns: 110px minmax(0, 1fr);
  gap: clamp(1rem, 3vw, 2.5rem);
  padding-block: 1.15rem;
  border-top: 1px solid var(--line);
}
.awards li:first-child { border-top: none; padding-top: 0; }
.award-year {
  font-family: var(--serif);
  font-style: italic;
  color: var(--accent);
  font-size: 1.05rem;
}
.award-name { font-weight: 500; font-size: 1rem; margin-bottom: .1rem; }
.award-org { font-size: .88rem; color: var(--muted); }

/* Contact */

.contact-lede {
  font-family: var(--serif);
  font-weight: 350;
  font-size: clamp(1.2rem, 2vw, 1.45rem);
  color: var(--ink-soft);
  margin-bottom: .9rem;
}
.contact-email { margin-bottom: 3rem; }
.contact-email a {
  font-family: var(--serif);
  font-style: italic;
  font-weight: 400;
  font-size: clamp(1.35rem, 3.2vw, 2.15rem);
  letter-spacing: .002em;
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: color .25s ease, border-color .25s ease;
}
.contact-email a:hover { color: var(--accent); border-bottom-color: var(--accent); }

.contact-cols {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(1.8rem, 4vw, 3.4rem);
  max-width: 40em;
}
.contact-cols .prose { font-size: .95rem; }
.contact-cols a { color: var(--ink-soft); text-underline-offset: .18em; text-decoration-color: var(--line); }
.contact-cols a:hover { color: var(--accent); text-decoration-color: var(--accent); }

/* Footer */

.site-foot { border-top: 1px solid var(--line); padding-block: 1.6rem 2.2rem; }
.foot-row {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  font-size: .82rem;
  color: var(--muted);
}
.foot-colophon { font-family: var(--serif); font-style: italic; }

/* ── Reveal on scroll ───────────────────── */

.reveal { opacity: 0; transform: translateY(12px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }
.d1 { transition-delay: .08s; }
.d2 { transition-delay: .16s; }
.d3 { transition-delay: .24s; }
.d4 { transition-delay: .32s; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* ── Responsive ─────────────────────────── */

@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; }
  .hero-photo { justify-self: start; margin-left: 2.3rem; width: min(78vw, 360px); }
  .section-grid { grid-template-columns: 1fr; gap: 1.6rem; }
  .section-label { position: static; }
  .areas { grid-template-columns: 1fr; gap: 1.2rem; }
  .teach-cols, .contact-cols { grid-template-columns: 1fr; }
  .year-group { grid-template-columns: 1fr; gap: 0; }
  .year { position: static; padding-top: 1.6rem; font-size: 1.45rem; }
}

@media (max-width: 640px) {
  .head-row { flex-direction: column; align-items: flex-start; gap: .5rem; padding-block: .85rem; }
  .site-nav { flex-wrap: wrap; gap: .8rem 1.1rem; }
  html { scroll-padding-top: 7.5rem; }
  .awards li { grid-template-columns: 1fr; gap: .15rem; }
}