/* Dr. Jacob Chengwei Feng — personal site
   Palette: warm ivory + ink + jade + burnished bronze
   Type: Libre Caslon Display (display) + Lora (body)
*/

:root {
  --bg: #f4ede0;
  --bg-soft: #ece4d3;
  --bg-card: #fbf6ec;
  --ink: #1a1818;
  --ink-soft: #3a3633;
  --ink-mute: #6b645c;
  --jade: #3d6b5c;
  --jade-soft: #6a9082;
  --jade-deep: #284b40;
  --bronze: #8a6a3a;
  --bronze-soft: #b89762;
  --rule: #d6caad;
  --rule-soft: #e6ddc7;
  --max: 1180px;
  --col: 720px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: 'Lora', Georgia, serif;
  font-size: 18px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4, .display {
  font-family: 'Libre Caslon Display', 'Libre Caslon Text', Georgia, serif;
  font-weight: 400;
  color: var(--ink);
  letter-spacing: -0.005em;
}

a {
  color: var(--jade);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color .15s, color .15s;
}
a:hover { border-bottom-color: var(--jade); color: var(--jade-deep); }

p { margin: 0 0 1em; }

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

/* ─── header / nav ─── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(244, 237, 224, 0.94);
  backdrop-filter: saturate(160%) blur(6px);
  border-bottom: 1px solid var(--rule-soft);
}
.nav-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
}
.nav-brand {
  font-family: 'Libre Caslon Display', Georgia, serif;
  font-size: 18px;
  letter-spacing: 0.02em;
  color: var(--ink);
  border: 0;
}
.nav-brand .ampersand { color: var(--jade); padding: 0 .15em; font-style: italic; }
.nav-links {
  display: flex;
  gap: 22px;
  font-size: 14px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}
.nav-links a {
  color: var(--ink-soft);
  border: 0;
  font-family: 'Lora', serif;
}
.nav-links a:hover { color: var(--jade-deep); }
.nav-toggle {
  display: none;
  background: none;
  border: 0;
  font-size: 22px;
  color: var(--ink);
  cursor: pointer;
  padding: 4px 8px;
}
@media (max-width: 760px) {
  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--rule);
    flex-direction: column;
    gap: 0;
    padding: 12px 0;
    display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 10px 28px; }
  .nav-toggle { display: inline-block; }
}

/* ─── hero ─── */
.hero {
  padding: 80px 0 56px;
  border-bottom: 1px solid var(--rule);
  background:
    radial-gradient(circle at 85% 12%, rgba(61,107,92,0.06), transparent 55%),
    radial-gradient(circle at 8% 95%, rgba(138,106,58,0.05), transparent 50%);
}
.hero-grid {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 56px;
  align-items: center;
}
.eyebrow {
  font-size: 12px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--bronze);
  font-family: 'Lora', serif;
  margin-bottom: 18px;
}
.hero h1 {
  font-size: clamp(38px, 5.5vw, 64px);
  line-height: 1.05;
  margin: 0 0 18px;
}
.hero h1 .ampersand { color: var(--jade); font-style: italic; padding: 0 .1em; }
.hero-tag {
  font-size: clamp(18px, 2vw, 22px);
  line-height: 1.45;
  color: var(--ink-soft);
  font-style: italic;
  font-family: 'Libre Caslon Display', Georgia, serif;
  margin: 0 0 28px;
  max-width: 580px;
}
.hero-intro {
  font-size: 17px;
  color: var(--ink-soft);
  max-width: 580px;
  margin-bottom: 32px;
}
.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}
.btn {
  display: inline-block;
  padding: 12px 22px;
  font-family: 'Lora', serif;
  font-size: 15px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  border: 1px solid var(--jade);
  background: transparent;
  color: var(--jade-deep);
  cursor: pointer;
  transition: background .15s, color .15s;
  border-radius: 0;
}
.btn:hover { background: var(--jade); color: var(--bg); border-bottom-color: var(--jade); }
.btn-primary { background: var(--jade); color: var(--bg); }
.btn-primary:hover { background: var(--jade-deep); color: var(--bg); }

.hero-portrait {
  width: 240px;
  height: 240px;
  overflow: hidden;
  background: var(--bg-soft);
  position: relative;
  box-shadow:
    0 1px 0 var(--rule),
    16px 16px 0 -2px var(--jade-soft);
}
.hero-portrait img { width: 100%; height: 100%; object-fit: cover; display: block; }

@media (max-width: 860px) {
  .hero { padding: 56px 0 40px; }
  .hero-grid { grid-template-columns: 1fr; gap: 28px; }
  .hero-portrait { width: 160px; height: 160px; box-shadow: 0 1px 0 var(--rule), 10px 10px 0 -2px var(--jade-soft); }
}

/* ─── section primitives ─── */
section { padding: 72px 0; border-bottom: 1px solid var(--rule); }
section:last-of-type { border-bottom: 0; }
.section-eyebrow {
  font-size: 12px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--bronze);
  margin-bottom: 14px;
}
.section-title {
  font-size: clamp(28px, 3.5vw, 42px);
  line-height: 1.1;
  margin: 0 0 8px;
}
.section-lede {
  font-size: 19px;
  color: var(--ink-soft);
  max-width: 720px;
  margin: 0 0 36px;
  font-style: italic;
  font-family: 'Libre Caslon Display', Georgia, serif;
}
.section-rule {
  width: 60px;
  border: 0;
  border-top: 1px solid var(--bronze);
  margin: 0 0 28px;
}

/* ─── about ─── */
.about-grid {
  display: grid;
  grid-template-columns: 1.4fr 1fr;
  gap: 56px;
  align-items: start;
}
.bio p { font-size: 18px; line-height: 1.65; }
.bio p:first-of-type::first-letter {
  font-family: 'Libre Caslon Display', Georgia, serif;
  font-size: 3.6em;
  float: left;
  line-height: 0.88;
  padding: 0.05em 0.12em 0 0;
  color: var(--jade);
}
.about-aside {
  background: var(--bg-card);
  padding: 28px 32px;
  border-left: 2px solid var(--bronze);
}
.about-aside h3 {
  font-size: 13px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--bronze);
  font-family: 'Lora', serif;
  margin: 0 0 10px;
}
.about-aside ul {
  list-style: none;
  margin: 0 0 20px;
  padding: 0;
  font-size: 15.5px;
  line-height: 1.5;
}
.about-aside li { padding: 4px 0; border-bottom: 1px dotted var(--rule-soft); }
.about-aside li:last-child { border-bottom: 0; }
.about-aside .role { color: var(--ink); }
.about-aside .institution { color: var(--ink-mute); font-style: italic; display: block; font-size: 14px; }
@media (max-width: 860px) {
  .about-grid { grid-template-columns: 1fr; gap: 32px; }
}

/* ─── books ─── */
.books-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
}
.book-card {
  display: grid;
  grid-template-columns: 180px 1fr;
  gap: 24px;
}
.book-cover {
  width: 180px;
  background: var(--bg-soft);
  box-shadow: 0 4px 18px rgba(26,24,24,0.18), 0 1px 0 rgba(0,0,0,0.04);
}
.book-cover img { width: 100%; height: auto; display: block; }
.book-card h3 {
  font-size: 22px;
  line-height: 1.2;
  margin: 0 0 6px;
}
.book-meta {
  font-size: 14px;
  color: var(--ink-mute);
  font-style: italic;
  margin-bottom: 12px;
}
.book-card p { font-size: 15.5px; color: var(--ink-soft); line-height: 1.55; }
.book-links { display: flex; flex-wrap: wrap; gap: 14px; font-size: 14px; margin-top: 10px; }
.book-links a {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  border-bottom: 1px solid var(--jade-soft);
  padding-bottom: 2px;
}
.oa-tag {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  background: var(--jade);
  color: var(--bg);
  padding: 3px 10px;
  margin-bottom: 12px;
  font-family: 'Lora', serif;
}
@media (max-width: 860px) {
  .books-grid { grid-template-columns: 1fr; gap: 40px; }
  .book-card { grid-template-columns: 140px 1fr; gap: 20px; }
  .book-cover { width: 140px; }
}

/* ─── research areas ─── */
.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  margin-bottom: 36px;
}
.research-card {
  padding: 22px 22px 24px;
  background: var(--bg-card);
  border-top: 2px solid var(--jade);
  transition: transform .15s, box-shadow .15s;
}
.research-card:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(26,24,24,0.06); }
.research-card .num {
  font-family: 'Libre Caslon Display', Georgia, serif;
  color: var(--bronze);
  font-size: 14px;
  letter-spacing: 0.18em;
  display: block;
  margin-bottom: 8px;
}
.research-card h4 {
  font-size: 17px;
  line-height: 1.3;
  margin: 0;
  color: var(--ink);
}

.qi-feature {
  background: var(--bg-card);
  padding: 36px 40px;
  border-left: 3px solid var(--jade);
  margin-top: 16px;
}
.qi-feature h3 {
  font-size: 24px;
  margin: 0 0 12px;
  color: var(--jade-deep);
}
.qi-feature p { margin: 0; color: var(--ink-soft); font-size: 16px; }

/* ─── articles carousel ─── */
.carousel-wrap {
  position: relative;
  margin: 0 -28px;
}
.carousel {
  display: flex;
  gap: 18px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  padding: 8px 28px 28px;
  scrollbar-width: thin;
  scrollbar-color: var(--bronze-soft) transparent;
}
.carousel::-webkit-scrollbar { height: 8px; }
.carousel::-webkit-scrollbar-thumb { background: var(--bronze-soft); border-radius: 4px; }
.article-card {
  flex: 0 0 320px;
  scroll-snap-align: start;
  background: var(--bg-card);
  padding: 22px 24px 24px;
  border-top: 1px solid var(--rule);
  position: relative;
  display: flex;
  flex-direction: column;
}
.article-card .journal {
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--bronze);
  margin-bottom: 8px;
  font-family: 'Lora', serif;
}
.article-card h4 {
  font-size: 17px;
  line-height: 1.3;
  margin: 0 0 10px;
  flex: 1;
}
.article-card .meta {
  font-size: 13.5px;
  color: var(--ink-mute);
  font-style: italic;
  margin-bottom: 12px;
}
.article-card .doi {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border-bottom: 1px solid var(--jade-soft);
  padding-bottom: 2px;
  align-self: flex-start;
}

/* ─── full publications collapsible ─── */
.pubs-toggle {
  display: inline-block;
  margin-top: 24px;
  font-size: 14px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  border-bottom: 1px solid var(--bronze);
  cursor: pointer;
  color: var(--ink-soft);
  background: none;
  border-top: 0;
  border-left: 0;
  border-right: 0;
  padding: 6px 0;
  font-family: 'Lora', serif;
}
.pubs-toggle:hover { color: var(--jade-deep); border-bottom-color: var(--jade); }
.pubs-full {
  display: none;
  margin-top: 32px;
  background: var(--bg-card);
  padding: 36px 40px;
}
.pubs-full.open { display: block; }
.pubs-full h3 {
  font-size: 18px;
  margin: 0 0 14px;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--bronze);
  font-family: 'Lora', serif;
}
.pubs-full h3:not(:first-child) { margin-top: 28px; }
.pubs-full ol {
  padding-left: 22px;
  margin: 0;
  font-size: 15.5px;
  line-height: 1.55;
}
.pubs-full ol li { padding: 6px 0; color: var(--ink-soft); }
.pubs-full em { color: var(--ink); }
.pubs-full a { color: var(--jade-deep); border-bottom: 1px solid var(--rule); }
.pubs-full a:hover { border-bottom-color: var(--jade); }

/* ─── lectures (video grid) ─── */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 22px;
}
.video-card {
  background: var(--bg-card);
  display: flex;
  flex-direction: column;
  cursor: pointer;
  border: 1px solid var(--rule-soft);
  transition: border-color .15s, transform .15s;
}
.video-card:hover { border-color: var(--jade); transform: translateY(-2px); }
.video-thumb {
  position: relative;
  aspect-ratio: 16 / 9;
  background: var(--ink);
  overflow: hidden;
}
.video-thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.video-thumb::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 50% 50%, rgba(0,0,0,0) 28%, rgba(0,0,0,0.32) 70%);
  pointer-events: none;
}
.play-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 54px;
  height: 54px;
  margin: -27px 0 0 -27px;
  border-radius: 50%;
  background: rgba(244, 237, 224, 0.95);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform .15s, background .15s;
  pointer-events: none;
}
.video-card:hover .play-btn { transform: scale(1.08); background: var(--jade); }
.video-card:hover .play-btn::before { border-left-color: var(--bg); }
.play-btn::before {
  content: "";
  width: 0; height: 0;
  border-style: solid;
  border-width: 9px 0 9px 15px;
  border-color: transparent transparent transparent var(--jade-deep);
  margin-left: 4px;
  transition: border-color .15s;
}
.video-meta { padding: 14px 18px 18px; }
.video-date {
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--bronze);
  margin-bottom: 6px;
}
.video-title {
  font-size: 15px;
  line-height: 1.35;
  color: var(--ink);
  margin: 0;
}
.video-venue {
  font-size: 13px;
  color: var(--ink-mute);
  font-style: italic;
  margin-top: 6px;
}

/* ─── conference talks (carousel) ─── */
.talk-card {
  flex: 0 0 320px;
  scroll-snap-align: start;
  background: var(--bg-card);
  padding: 22px 24px;
  border-top: 1px solid var(--rule);
  display: flex;
  flex-direction: column;
}
.talk-card .date {
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--bronze);
  margin-bottom: 8px;
}
.talk-card h4 {
  font-size: 16px;
  line-height: 1.35;
  margin: 0 0 10px;
  flex: 1;
}
.talk-card .venue {
  font-size: 13.5px;
  color: var(--ink-mute);
  font-style: italic;
}

/* ─── teaching ─── */
.teaching-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 36px;
}
.teaching-block h3 {
  font-size: 14px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--bronze);
  margin: 0 0 16px;
  font-family: 'Lora', serif;
  font-weight: 600;
}
.teaching-block ul {
  list-style: none;
  padding: 0;
  margin: 0;
}
.teaching-block li {
  padding: 12px 0;
  border-bottom: 1px solid var(--rule-soft);
  font-size: 16px;
  line-height: 1.45;
}
.teaching-block li:last-child { border-bottom: 0; }
.teaching-block .term {
  display: block;
  font-size: 13px;
  color: var(--ink-mute);
  font-style: italic;
  margin-top: 4px;
}
.teaching-block .inst {
  display: block;
  font-size: 13px;
  color: var(--ink-mute);
  margin-top: 4px;
}
.teaching-flagship {
  grid-column: 1 / -1;
  background: var(--bg-card);
  padding: 28px 32px;
  border-left: 3px solid var(--jade);
}
.teaching-flagship h3 {
  font-family: 'Libre Caslon Display', Georgia, serif;
  font-size: 24px;
  text-transform: none;
  letter-spacing: 0;
  color: var(--jade-deep);
  font-weight: 400;
  margin: 0 0 10px;
}
.teaching-flagship p { margin: 0; color: var(--ink-soft); font-size: 15.5px; }
@media (max-width: 760px) {
  .teaching-grid { grid-template-columns: 1fr; gap: 28px; }
}

/* ─── events ─── */
.events-list {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}
.event-card {
  background: var(--bg-card);
  padding: 24px 28px;
  border-top: 1px solid var(--rule);
}
.event-card .date {
  font-size: 12px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--bronze);
  margin-bottom: 10px;
}
.event-card h4 {
  font-size: 18px;
  line-height: 1.3;
  margin: 0 0 8px;
}
.event-card .meta { font-size: 14px; color: var(--ink-mute); font-style: italic; }
.event-card .role { font-size: 13px; color: var(--jade-deep); text-transform: uppercase; letter-spacing: 0.12em; margin-top: 8px; }
@media (max-width: 760px) {
  .events-list { grid-template-columns: 1fr; }
}

/* ─── contact / footer ─── */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 56px;
  align-items: start;
}
.contact-block h3 {
  font-size: 13px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--bronze);
  font-family: 'Lora', serif;
  margin: 0 0 14px;
}
.contact-email {
  font-family: 'Libre Caslon Display', Georgia, serif;
  font-size: 22px;
  display: block;
  margin-bottom: 8px;
  color: var(--ink);
  border: 0;
}
.contact-email:hover { color: var(--jade-deep); }
.contact-block ul { list-style: none; padding: 0; margin: 0; }
.contact-block li { padding: 6px 0; font-size: 15px; }
.contact-block li a { color: var(--ink-soft); }
@media (max-width: 760px) { .contact-grid { grid-template-columns: 1fr; gap: 28px; } }

footer.site-footer {
  background: var(--ink);
  color: var(--bg);
  padding: 36px 0;
  font-size: 14px;
}
footer.site-footer a { color: var(--bg); }
footer.site-footer .container { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 16px; }
footer.site-footer .copyright { opacity: 0.7; }

/* ─── modal for video playback ─── */
.video-modal {
  position: fixed;
  inset: 0;
  background: rgba(15, 12, 10, 0.92);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 28px;
}
.video-modal.open { display: flex; }
.video-modal-frame {
  width: min(960px, 100%);
  aspect-ratio: 16 / 9;
  background: #000;
  position: relative;
}
.video-modal iframe { width: 100%; height: 100%; border: 0; display: block; }
.video-modal-close {
  position: absolute;
  top: -36px;
  right: 0;
  background: transparent;
  border: 0;
  color: var(--bg);
  font-size: 24px;
  cursor: pointer;
  font-family: 'Libre Caslon Display', Georgia, serif;
}

/* ─── version switcher (shared with v2) ─── */
.version-switch {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background: var(--ink);
  color: var(--bg);
  padding: 6px;
  display: flex;
  gap: 4px;
  z-index: 200;
  border-radius: 2px;
  box-shadow: 0 6px 24px rgba(0,0,0,0.25);
  font-size: 13px;
  letter-spacing: 0.12em;
  font-family: 'Lora', serif;
}
.version-switch a {
  display: inline-block;
  padding: 8px 16px;
  color: var(--bg);
  border: 0;
  text-decoration: none;
  background: transparent;
  border-radius: 2px;
  transition: background .15s;
}
.version-switch a:hover { background: rgba(255,255,255,0.12); }
.version-switch a.active {
  background: var(--jade);
  color: var(--bg);
  pointer-events: none;
  cursor: default;
}