/* ============================================================
   SITE — single-page redesign for Jin Sun's homepage
   Warm paper background, serif display type, terracotta accent.
   ============================================================ */

:root {
  --font-sans: "DM Sans", system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-serif: "Source Serif 4", "Georgia", "Times New Roman", serif;

  --bg: #fbfaf7;
  --bg-translucent: rgba(251, 250, 247, 0.85);
  --ink: #2a3140;
  --ink-soft: #535d6e;
  --ink-faint: #807d78;
  --hairline: #e6e2da;

  --accent: #8a5a44;
  --accent-soft: #e4ecf2;
  --accent-faint: #f7f5f0;
  --accent-light: #c9dff0;

  --ink-panel: #2d4558;
  --ink-panel-line: #3f5a70;
  --bg-soft: #c9dff0;
  --bg-faint: rgba(255, 251, 245, 0.72);

  --shadow-soft: 0 18px 36px -22px rgba(20, 28, 44, 0.35);
  --radius: 3px;
  --radius-md: 10px;
}

* {
  box-sizing: border-box;
}

html {
  scrollbar-gutter: stable;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.6;
  color: var(--ink);
  background:
    radial-gradient(ellipse 1200px 700px at 50% -10%, var(--accent-faint), transparent),
    var(--bg);
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.container {
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 48px;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(14px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ---------- Nav ---------- */
.site-nav-bar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 48px;
  background: var(--bg-translucent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--hairline);
}

.site-nav-bar .brand-name {
  font-family: var(--font-serif);
  font-size: 20px;
  letter-spacing: 0.02em;
  color: var(--ink);
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}

.site-nav-bar.is-scrolled .brand-name {
  opacity: 1;
  pointer-events: auto;
}

.site-nav-bar nav {
  display: flex;
  gap: 36px;
}

.site-nav-bar nav a {
  font-size: 12.5px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-soft);
  padding-bottom: 3px;
  border-bottom: 1px solid transparent;
  transition: color 0.2s, border-color 0.2s;
}

.site-nav-bar nav a:hover {
  color: var(--accent);
  border-color: var(--accent);
  text-decoration: none;
}

/* ---------- Section divider ---------- */
.divider {
  max-width: 1068px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 56px;
}

.divider .line { flex: 1; height: 1px; background: var(--hairline); }
.divider .diamond { width: 6px; height: 6px; transform: rotate(45deg); border: 1px solid var(--accent); flex-shrink: 0; }

/* ---------- Section shell ---------- */
.page-section {
  max-width: 1180px;
  margin: 0 auto;
  padding: 52px 48px;
  position: relative;
}

.section-kicker {
  position: relative;
  margin-bottom: 28px;
  display: flex;
  align-items: center;
  gap: 40px;
  flex-wrap: wrap;
}

.section-kicker .glyph {
  position: absolute;
  left: -14px;
  top: -26px;
  font-family: var(--font-serif);
  font-size: 72px;
  color: var(--accent);
  opacity: 0.08;
  line-height: 1;
  user-select: none;
}

.section-kicker .label-row {
  display: flex;
  align-items: center;
  gap: 12px;
  position: relative;
  flex-shrink: 0;
}

.section-kicker .label-row .tick {
  width: 22px;
  height: 1px;
  background: var(--accent);
}

.section-kicker .label-row span.label {
  font-size: 13px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
}

.section-kicker .kicker-lead {
  font-size: 16px;
  color: var(--ink-soft);
  line-height: 1.65;
  margin: 0;
  flex: 1;
  min-width: 280px;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  max-width: 1180px;
  margin: 0 auto;
  padding: 56px 48px 44px;
  display: grid;
  grid-template-columns: 1.3fr 0.7fr;
  gap: 44px;
  align-items: center;
  overflow: hidden;
}

.hero .drop-cap {
  position: absolute;
  left: -40px;
  top: -60px;
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 220px;
  line-height: 1;
  color: var(--accent);
  opacity: 0.05;
  pointer-events: none;
  user-select: none;
}

.hero-copy {
  position: relative;
  animation: fadeUp 0.9s ease both;
}

.hero-kicker {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 26px;
}

.hero-kicker .tick { width: 34px; height: 1px; background: var(--accent); }

.hero-kicker span.tagline {
  font-family: var(--font-serif);
  font-style: italic;
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--accent);
}

.hero-copy h1 {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: clamp(2.4rem, 4.5vw, 3.5rem);
  line-height: 1.05;
  margin: 0 0 16px;
  letter-spacing: 0.005em;
}

.hero-copy p {
  font-size: 15px;
  line-height: 1.6;
  color: var(--ink-soft);
  max-width: 520px;
  margin: 0 0 16px;
}

.hero-copy p.hero-lede { font-size: 16px; }

.hero-copy p a { color: var(--accent); }

.hero-links {
  display: flex;
  gap: 28px;
  align-items: center;
  margin-top: 6px;
}

.hero-links a {
  font-size: 14px;
  letter-spacing: 0.04em;
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 3px;
}

.hero-links a:hover { text-decoration: none; }

.hero-photo {
  position: relative;
  animation: fadeUp 1.1s ease 0.15s both;
}

.hero-photo .frame {
  position: absolute;
  inset: -14px;
  border: 1px solid var(--hairline);
  border-radius: 4px;
  pointer-events: none;
}

.hero-photo .corner {
  position: absolute;
  width: 22px;
  height: 22px;
  pointer-events: none;
}

.hero-photo .corner.tl { top: -8px; left: -8px; border-top: 1px solid var(--accent); border-left: 1px solid var(--accent); }
.hero-photo .corner.br { bottom: -8px; right: -8px; border-bottom: 1px solid var(--accent); border-right: 1px solid var(--accent); }

.hero-photo img {
  width: 100%;
  height: 340px;
  object-fit: cover;
  border-radius: 4px;
}

/* ---------- News ---------- */
.news-body {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 24px;
}

.news-eyebrow {
  font-size: 13px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-faint);
}

.news-list { display: flex; flex-direction: column; }

.news-item {
  display: grid;
  grid-template-columns: 76px 1fr auto;
  align-items: center;
  gap: 20px;
  padding: 10px 0;
  border-top: 1px solid var(--hairline);
}

.news-date {
  font-family: var(--font-serif);
  font-size: 14px;
  color: var(--accent);
}

.news-title { font-size: 15px; line-height: 1.5; color: var(--ink-soft); }
.news-title a { color: var(--ink-soft); }
.news-title a:hover { color: var(--accent); }

.news-description { font-size: 13px; color: var(--ink-faint); line-height: 1.45; margin-top: 2px; }

.news-type-icon {
  width: 22px; height: 22px; border-radius: 6px;
  display: grid; place-items: center;
  background: var(--accent-soft); color: var(--accent);
  font-size: 0.7rem;
}

.news-past { display: none; flex-direction: column; }
.news-past.is-expanded { display: flex; }

.news-expand-btn {
  margin-top: 14px;
  background: none;
  border: none;
  padding: 0;
  font-family: var(--font-sans);
  font-size: 13px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  cursor: pointer;
}

.news-expand-btn:hover { text-decoration: underline; }

/* ---------- Pillars ---------- */
.pillars {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 8px;
}

.pillar-card {
  padding: 22px 20px;
  border: 1px solid var(--hairline);
  border-radius: var(--radius);
  background: #f2f4f2;
  box-shadow: var(--shadow-soft);
}

.pillar-card h3 {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: 20px;
  margin: 0 0 8px;
}

.pillar-card p {
  font-size: 13.5px;
  line-height: 1.55;
  color: var(--ink-soft);
  margin: 0 0 12px;
}

.pillar-tags { display: flex; flex-wrap: wrap; gap: 8px; }

.pillar-tags span {
  font-size: 12px;
  letter-spacing: 0.03em;
  color: #f4f8fc;
  background: #4a6f9e;
  padding: 5px 11px;
  border-radius: 20px;
}

/* ---------- Publications ---------- */
.pub-section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin: 40px 0 18px;
  flex-wrap: wrap;
  gap: 10px;
}

.pub-section-head h3 {
  font-family: var(--font-serif);
  font-weight: 500;
  font-size: 22px;
  margin: 0;
}

.pub-controls { display: flex; flex-wrap: wrap; gap: 0.7rem; justify-content: space-between; align-items: center; margin-bottom: 1rem; }
.pub-filters { display: flex; gap: 0.3rem; flex-wrap: wrap; }
.pub-filter-button {
  font-family: var(--font-sans); font-size: 0.78rem; color: var(--ink-soft);
  background: rgba(255,255,255,0.6); border: 1px solid var(--hairline); border-radius: 999px;
  padding: 0.3rem 0.85rem; cursor: pointer; transition: all .18s;
}
.pub-filter-button:hover { color: var(--accent); border-color: var(--accent); }
.pub-filter-button.is-active { background: var(--accent); color: #fff; border-color: transparent; }
.pub-search { display: flex; flex: 1; min-width: 200px; max-width: 320px; }
#pub-search-input {
  width: 100%; font-family: var(--font-sans); font-size: 0.82rem; color: var(--ink);
  background: rgba(255,255,255,0.7); border: 1px solid var(--hairline); border-radius: 999px;
  padding: 0.4rem 0.95rem;
}
#pub-search-input::placeholder { color: var(--ink-faint); }
#pub-search-input:focus { outline: none; border-color: var(--accent); }

.publications-list { display: flex; flex-direction: column; gap: 1.3rem; }
.pub-year-group { display: flex; flex-direction: column; gap: 0; }
.pub-year-heading {
  font-family: var(--font-serif); font-size: 15px; color: var(--accent);
  border-bottom: 1px solid var(--hairline); padding-bottom: 0.4rem; margin-bottom: 0.2rem;
}

.pub-item {
  padding: 12px 10px;
  border-top: 1px solid var(--hairline);
  border-radius: var(--radius);
  transition: background-color 0.15s;
}
.pub-item:hover { background-color: rgba(138, 90, 68, 0.05); }
.pub-item.pub-highlight { background: var(--accent-faint); border-left: 3px solid var(--accent); padding-left: 14px; }
.pub-title { font-size: 15.5px; color: var(--ink); line-height: 1.5; margin-bottom: 4px; }
.pub-title a { color: var(--ink); }
.pub-title a:hover { color: var(--accent); }
.pub-authors { font-size: 13px; color: var(--ink-faint); font-family: "Courier New", monospace; }
.pub-authors strong { color: var(--accent); font-weight: 600; }
.pub-meta { font-size: 12.5px; color: var(--ink-faint); margin-top: 0.25rem; }
.pub-links { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 0.45rem; }
.pub-link {
  font-size: 0.72rem; color: var(--accent); border: 1px solid var(--hairline); border-radius: 999px;
  padding: 0.16rem 0.6rem; background: rgba(255,255,255,0.6);
}
.pub-link:hover { color: #fff; background: var(--accent); text-decoration: none; }
.pub-tags { display: flex; flex-wrap: wrap; gap: 0.25rem; margin-top: 0.4rem; }
.pub-tag-pill { font-size: 0.66rem; background: var(--accent-soft); color: #2d4c62; padding: 0.14rem 0.5rem; border-radius: 999px; }

/* ---------- Teaching ---------- */
.current-course-card {
  padding: 36px 40px;
  border: 1px solid var(--accent-light);
  background: var(--accent-faint);
  border-radius: var(--radius);
  margin-bottom: 32px;
}

.current-course-card .eyebrow {
  font-size: 12px; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 12px;
}

.current-course-card h3 {
  font-family: var(--font-serif); font-weight: 500; font-size: 20px; margin: 0 0 6px;
}

.current-course-card p {
  font-size: 15px; color: var(--ink-soft); line-height: 1.55; margin: 0 0 10px; max-width: 640px;
}

.current-course-card a.course-link {
  font-size: 13.5px; letter-spacing: 0.03em; color: var(--accent);
  border-bottom: 1px solid var(--accent); padding-bottom: 2px;
}
.current-course-card a.course-link:hover { text-decoration: none; }

.past-courses-label {
  font-size: 13px; letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ink-faint); margin-bottom: 18px;
}

.table-wrapper { overflow-x: auto; border: 1px solid var(--hairline); border-radius: var(--radius); background: rgba(255,255,255,0.5); }
.course-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.course-table th {
  text-align: left; font-size: 0.68rem; letter-spacing: 0.06em; text-transform: uppercase;
  color: var(--ink-faint); padding: 0.6rem 0.9rem; border-bottom: 1px solid var(--hairline); white-space: nowrap;
}
.course-table td { padding: 0.6rem 0.9rem; border-bottom: 1px solid var(--hairline); color: var(--ink-soft); vertical-align: top; line-height: 1.45; }
.course-table tr:last-child td { border-bottom: 0; }
.course-table td:first-child { font-family: var(--font-serif); font-size: 0.85rem; color: var(--accent); white-space: nowrap; }

/* ---------- About ---------- */
.about-grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 44px; margin-top: 24px; }
.about-grid p { font-size: 16px; line-height: 1.65; color: var(--ink-soft); margin: 0 0 14px; }
.about-grid p a { color: var(--accent); }

.timeline { display: flex; flex-direction: column; gap: 0; margin: 0; padding: 0; list-style: none; }
.timeline-item {
  display: grid; grid-template-columns: 100px 1fr; gap: 16px;
  padding: 9px 0; border-top: 1px solid var(--hairline);
}
.timeline-range { font-family: var(--font-serif); font-size: 15px; color: var(--accent); }
.timeline-role { font-size: 14.5px; color: var(--ink); font-weight: 500; margin-bottom: 2px; }
.timeline-place { font-size: 13.5px; color: var(--ink-faint); }

.about-bio-block { margin-top: 28px; }
.about-bio-block .label {
  font-size: 12px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-faint); margin-bottom: 10px;
}

/* ---------- Footer / Contact ---------- */
.contact-footer { background: var(--ink-panel); margin-top: 40px; }

.contact-footer-inner {
  max-width: 1180px; margin: 0 auto; padding: 44px 48px 28px;
  display: grid; grid-template-columns: 1fr 1fr; gap: 32px;
}

.contact-footer .footer-name { font-family: var(--font-serif); font-size: 26px; color: var(--bg); margin-bottom: 16px; }
.contact-footer .footer-address { font-size: 14.5px; line-height: 1.8; color: var(--bg-soft); max-width: 320px; margin: 0; }

.contact-footer .footer-cols { display: flex; gap: 56px; justify-content: flex-end; flex-wrap: wrap; }
.contact-footer .col-label {
  font-size: 12px; letter-spacing: 0.1em; text-transform: uppercase; color: var(--bg-faint); margin-bottom: 14px;
}
.contact-footer .connect-links { display: flex; flex-direction: column; gap: 10px; }
.contact-footer .connect-links a { font-size: 14px; color: var(--bg-soft); }
.contact-footer .connect-links a:hover { color: var(--accent-light); text-decoration: none; }

.sponsor-grid { display: grid; grid-template-columns: repeat(2, 56px); gap: 12px; }
.sponsor-grid img { width: 56px; height: 32px; object-fit: contain; filter: grayscale(1) brightness(1.8); }

.contact-footer .footer-legal {
  max-width: 1180px; margin: 0 auto; padding: 16px 48px;
  border-top: 1px solid var(--ink-panel-line); font-size: 12.5px; color: var(--bg-faint);
}

.footer-inner { font-size: 0.78rem; color: var(--bg-faint); }
.footer-inner p { margin: 0; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .hero { grid-template-columns: 1fr; }
  .pillars { grid-template-columns: 1fr; }
  .about-grid { grid-template-columns: 1fr; }
  .news-body { grid-template-columns: 1fr; }
  .contact-footer-inner { grid-template-columns: 1fr; }
  .contact-footer .footer-cols { justify-content: flex-start; }
}

@media (max-width: 640px) {
  .site-nav-bar { padding: 12px 20px; }
  .site-nav-bar nav { gap: 18px; }
  .page-section, .hero, .divider { padding-left: 20px; padding-right: 20px; }
  .news-item, .timeline-item { grid-template-columns: 1fr; gap: 4px; }
  .course-table td:first-child { white-space: normal; }
}

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

/* ---------- Course subpages (e.g. _teaching/<term>/index.html) ---------- */
.subpage-nav {
  position: sticky; top: 0; z-index: 50;
  background: var(--bg-translucent); backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--hairline);
}
.subpage-nav-inner {
  max-width: 880px; margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 48px;
}
.subpage-nav .brand-name { font-family: var(--font-serif); font-size: 20px; color: var(--ink); }
.subpage-nav nav { display: flex; gap: 28px; }
.subpage-nav nav a {
  font-size: 12.5px; letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-soft);
  padding-bottom: 3px; border-bottom: 1px solid transparent; transition: color 0.2s, border-color 0.2s;
}
.subpage-nav nav a:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }

.course-main { max-width: 880px; margin: 0 auto; padding: 44px 48px 60px; }
.course-eyebrow { font-size: 12px; letter-spacing: 0.14em; text-transform: uppercase; color: var(--accent); margin: 0 0 0.6rem; }
.course-title { font-family: var(--font-serif); font-weight: 500; font-size: clamp(1.7rem, 3vw, 2.3rem); margin: 0 0 0.9rem; color: var(--ink); }
.course-lead { font-size: 15px; line-height: 1.65; color: var(--ink-soft); margin: 0 0 1.2rem; }

.course-section { margin-top: 2.2rem; }
.course-section h2 {
  font-family: var(--font-serif); font-weight: 500; font-size: 1.25rem; margin: 0 0 0.7rem;
  border-bottom: 1px solid var(--hairline); padding-bottom: 0.4rem; color: var(--ink);
}
.course-section .sub { font-size: 0.86rem; color: var(--ink-faint); margin: -0.3rem 0 0.7rem; }

.fact-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0.7rem; }
.fact-card {
  background: rgba(255,255,255,0.55); border: 1px solid var(--hairline); border-radius: var(--radius);
  padding: 0.9rem 1rem; box-shadow: var(--shadow-soft);
}
.fact-card h3 { font-family: var(--font-sans); font-size: 0.68rem; letter-spacing: 0.1em; text-transform: uppercase; color: var(--ink-faint); margin: 0 0 0.5rem; }
.fact-card p { font-size: 0.85rem; line-height: 1.55; color: var(--ink-soft); margin: 0 0 0.3rem; }
.fact-card p:last-child { margin-bottom: 0; }
.fact-card a { color: var(--accent); }

.plain-list { margin: 0; padding-left: 1.2rem; }
.plain-list li { font-size: 0.88rem; line-height: 1.6; color: var(--ink-soft); margin-bottom: 0.4rem; }

.sched-unit-row td {
  font-family: var(--font-serif); font-weight: 500; font-size: 0.88rem;
  color: var(--accent); background: var(--accent-faint);
  padding: 0.55rem 0.8rem;
}
.badge {
  display: inline-block; font-size: 0.64rem; letter-spacing: 0.03em; text-transform: uppercase;
  padding: 0.14rem 0.5rem; border-radius: 999px; white-space: nowrap;
}
.badge-lecture { background: var(--accent-soft); color: #2d4c62; }
.badge-discussion { background: rgba(128,125,120,0.16); color: var(--ink-faint); }
.badge-midterm { background: #fbe3d0; color: #9a4a1c; }
.badge-presentation { background: #e4dcf7; color: #5a3aa3; }
.badge-project { background: #d9f0df; color: #1f6b3a; }
.sched-note { font-size: 0.8rem; color: var(--ink-faint); margin: 0.5rem 0 0; }

.sched-next-row td { background: var(--accent-faint); }
.sched-next-row td:first-child { box-shadow: inset 3px 0 0 var(--accent); font-weight: 600; }
.sched-next-label {
  display: inline-block; margin-left: 0.5rem; font-family: var(--font-sans); font-size: 0.6rem;
  letter-spacing: 0.06em; text-transform: uppercase; color: #fff; background: var(--accent);
  padding: 0.12rem 0.4rem; border-radius: 999px; vertical-align: middle; white-space: nowrap;
}

.grading-table td:last-child { font-family: var(--font-serif); color: var(--accent); white-space: nowrap; }