/* =========================================================================
   Dongting Li — personal academic site
   Palette (五行 金水土 · 忌木火):
     纸白 paper · 砂岩 sandstone · 玄墨 ink · 石墨 graphite
     靛青 indigo (interaction only) · 鎏金 gold (rare accent) · 雾蓝 mist
   Type: Spectral (display) · Source Sans 3 (body) · JetBrains Mono (meta)
   ========================================================================= */

:root {
  --paper:      #f5f3ec;   /* 纸白 — warm paper, softer than #fff        */
  --sand:       #ece7db;   /* 砂岩 — section breathing layer             */
  --ink:        #1b2a33;   /* 玄墨 — water-tinged blue-black text        */
  --ink-soft:   #3b4a52;   /* softened ink for body copy                */
  --graphite:   #5e6b73;   /* 石墨 — dates, venues, captions            */
  --indigo:     #0e5c87;   /* 靛青 — the ONLY interactive color         */
  --indigo-deep:#0a4a6d;
  --gold:       #b58a3c;   /* 鎏金 — decorative accent, used sparingly  */
  --gold-ink:   #8a6b38;   /* legible gold for hover text               */
  --mist:       #dbe6ec;   /* 雾蓝 — highlight / quote background        */
  --line:       rgba(27, 42, 51, 0.13);
  --line-soft:  rgba(27, 42, 51, 0.07);
  --fold:       rgba(27, 42, 51, 0.020);
  --nav-bg:     rgba(245, 243, 236, 0.82);
  --shadow:     rgba(27, 42, 51, 0.50);

  --maxw: 1140px;
  --gut: clamp(1.25rem, 5vw, 4rem);

  --f-display: "Spectral", Georgia, "Times New Roman", serif;
  --f-body: "Source Sans 3", -apple-system, BlinkMacSystemFont, system-ui, sans-serif;
  --f-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;
  --f-fangsong: "STFangsong", "STFangSong", "FangSong", "仿宋", "FangSong_GB2312", "KaiTi", serif;

  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper:      #141d24;   /* deep water blue base, not pure black */
    --sand:       #1b2833;
    --ink:        #e8e6e0;   /* warm gray-white */
    --ink-soft:   #c4c8c9;
    --graphite:   #93a1a8;
    --indigo:     #6b9bbf;   /* brightened */
    --indigo-deep:#8fb7d4;
    --gold:       #c6a24e;
    --gold-ink:   #d4b46a;
    --mist:       #1f303b;
    --line:       rgba(232, 230, 224, 0.15);
    --line-soft:  rgba(232, 230, 224, 0.07);
    --fold:       rgba(232, 230, 224, 0.028);
    --nav-bg:     rgba(20, 29, 36, 0.82);
    --shadow:     rgba(0, 0, 0, 0.6);
  }
}

/* ----- Reset-ish ----- */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background-color: var(--paper);
  background-image:
    repeating-linear-gradient(135deg, var(--fold) 0 1px, transparent 1px 28px),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.022'/%3E%3C/svg%3E");
  color: var(--ink);
  font-family: var(--f-body);
  font-size: clamp(1rem, 0.5vw + 0.92rem, 1.08rem);
  line-height: 1.65;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

::selection { background: var(--indigo); color: #fff; }

/* ----- Layout helpers ----- */
.wrap { max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gut); }
.section { padding-block: clamp(1.75rem, 4vw, 3.5rem); }
.section--tight { padding-block: clamp(1.25rem, 3vw, 2.5rem); }

/* ----- Typography ----- */
h1, h2, h3, h4 { font-family: var(--f-display); font-weight: 500; line-height: 1.08; letter-spacing: -0.005em; margin: 0; color: var(--ink); }
.h-xl { font-size: clamp(2.7rem, 7vw, 5rem); font-weight: 500; }
.h-lg { font-size: clamp(2rem, 4.5vw, 3.1rem); }
.h-md { font-size: clamp(1.45rem, 3vw, 2rem); }
p { margin: 0 0 1.1em; max-width: 66ch; }
strong { font-weight: 600; color: var(--ink); }
em { font-style: italic; }

.eyebrow {
  font-family: var(--f-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--graphite);
  display: inline-flex;
  align-items: center;
  gap: 0.7rem;
  margin: 0 0 1.3rem;
}
.eyebrow::before {
  content: "";
  width: 2rem; height: 1px;
  background: var(--graphite);
  opacity: 0.6;
  display: inline-block;
}
.eyebrow .num { color: var(--gold-ink); font-weight: 500; }

.lede { font-size: clamp(1.12rem, 1.3vw, 1.35rem); color: var(--ink-soft); line-height: 1.55; }

/* ----- Inline links (content) — 靛青 ----- */
.link {
  color: var(--indigo);
  text-decoration: none;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 100% 1px;
  background-repeat: no-repeat;
  background-position: 0 100%;
  transition: color 0.2s, background-size 0.35s var(--ease);
  padding-bottom: 1px;
}
.link:hover { color: var(--gold-ink); background-size: 0 1px; }

/* =========================================================================
   Navigation
   ========================================================================= */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: saturate(140%) blur(10px);
  background: var(--nav-bg);
  border-bottom: 1px solid var(--line-soft);
}
.nav__inner {
  max-width: var(--maxw); margin-inline: auto;
  padding: 0.85rem var(--gut);
  display: flex; align-items: center; justify-content: space-between; gap: 1rem;
}
.brand {
  font-family: var(--f-mono);
  font-size: 0.88rem; letter-spacing: 0.01em; text-decoration: none;
  color: var(--ink); font-weight: 500; white-space: nowrap;
}
.brand b { color: var(--ink); font-weight: 700; }
.nav__links { display: flex; align-items: center; gap: clamp(0.6rem, 2vw, 2rem); list-style: none; margin: 0; padding: 0; }
.nav__links a {
  font-family: var(--f-mono);
  font-size: 0.76rem; letter-spacing: 0.05em; text-transform: uppercase;
  text-decoration: none; color: var(--graphite);
  padding: 0.35rem 0; position: relative;
  transition: color 0.2s;
}
.nav__links a::after {
  content: ""; position: absolute; left: 0; bottom: -1px; height: 1.5px; width: 0;
  background: var(--indigo); transition: width 0.3s var(--ease);
}
.nav__links a:hover { color: var(--ink); }
.nav__links a:hover::after { width: 100%; }
.nav__links a[aria-current="page"] { color: var(--indigo); }
.nav__links a[aria-current="page"]::after {
  width: 5px; height: 5px; border-radius: 50%; left: 50%; bottom: -4px;
  transform: translateX(-50%); background: var(--gold);
}

.nav__toggle {
  display: none; background: none; border: 1px solid var(--line);
  border-radius: 6px; padding: 0.4rem 0.55rem; cursor: pointer; color: var(--ink);
  font-family: var(--f-mono); font-size: 0.73rem;
}

@media (max-width: 680px) {
  .nav__toggle { display: inline-block; }
  .nav__links {
    position: absolute; top: 100%; right: var(--gut); left: var(--gut);
    flex-direction: column; align-items: flex-start; gap: 0;
    background: var(--sand); border: 1px solid var(--line);
    border-radius: 10px; padding: 0.4rem;
    box-shadow: 0 20px 40px -20px var(--shadow);
    transform-origin: top; transform: scaleY(0); opacity: 0;
    transition: transform 0.25s var(--ease), opacity 0.2s;
  }
  .nav__links.open { transform: scaleY(1); opacity: 1; }
  .nav__links a { width: 100%; padding: 0.7rem 0.6rem; font-size: 0.82rem; }
  .nav__links a::after { display: none; }
}

/* =========================================================================
   Hero
   ========================================================================= */
.hero { padding-top: clamp(2.5rem, 6vw, 5rem); padding-bottom: clamp(2.5rem, 6vw, 5rem); }
.hero__grid {
  display: grid; gap: clamp(2rem, 5vw, 4.5rem);
  grid-template-columns: 1.35fr 1fr; align-items: center;
}
.hero__title { margin-bottom: 1.3rem; }
.hero__title::after {
  content: ""; display: block; width: 64px; height: 3px;
  background: var(--gold); border-radius: 2px; margin-top: 1.3rem;
}
.hero__title .zh { font-size: 0.42em; color: var(--graphite); font-family: var(--f-fangsong); font-weight: 400; letter-spacing: 0.06em; white-space: nowrap; }
.fs { font-family: var(--f-fangsong); font-style: normal; }
.hero__role {
  font-family: var(--f-mono); font-size: 0.8rem; letter-spacing: 0.02em;
  color: var(--graphite); margin-bottom: 1.6rem; line-height: 1.8;
}
.hero__role b { color: var(--ink); font-weight: 600; }

/* portrait frame with gold offset */
.portrait {
  position: relative; align-self: center; justify-self: end;
  max-width: 340px; width: 100%;
}
.portrait__img {
  width: 100%; aspect-ratio: 4/5; object-fit: cover;
  border-radius: 3px;
  box-shadow: 0 30px 60px -30px var(--shadow);
  filter: saturate(1.01);
}
.portrait::before {
  content: ""; position: absolute; inset: 14px -14px -14px 14px;
  border: 1px solid var(--gold); border-radius: 3px; z-index: -1;
}
.portrait__tag {
  position: absolute; bottom: -0.8rem; left: -0.8rem;
  background: var(--ink); color: var(--paper);
  font-family: var(--f-mono); font-size: 0.66rem; letter-spacing: 0.08em;
  padding: 0.35rem 0.7rem; text-transform: uppercase; border-radius: 2px;
}

/* quick contact row */
.contacts { display: flex; flex-wrap: wrap; gap: 0.6rem 0.7rem; margin-top: 2rem; }
.chip {
  display: inline-flex; align-items: center; gap: 0.5rem;
  font-family: var(--f-mono); font-size: 0.74rem; letter-spacing: 0.01em;
  text-decoration: none; color: var(--ink);
  border: 1px solid var(--line); border-radius: 100px;
  padding: 0.5rem 0.95rem; background: var(--sand);
  transition: transform 0.2s var(--ease), border-color 0.2s, color 0.2s;
}
.chip:hover { transform: translateY(-2px); border-color: var(--indigo); color: var(--indigo); }
.chip svg { width: 15px; height: 15px; }

@media (max-width: 820px) {
  .hero__grid { grid-template-columns: 1fr; }
  .portrait { justify-self: start; order: -1; max-width: 260px; }
}

/* =========================================================================
   Section header block
   ========================================================================= */
.shead { margin-bottom: clamp(2rem, 4vw, 3.2rem); max-width: 60ch; }

/* =========================================================================
   Upcoming travel
   ========================================================================= */
.upcoming { margin-bottom: clamp(1.25rem, 2vw, 2rem); }
.upcoming > .eyebrow { margin-bottom: 0.7rem; }
.upcoming__items { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: 0.65rem; }

/* =========================================================================
   News / timeline
   ========================================================================= */
.news { display: grid; gap: 0; }
.news__year {
  display: grid; grid-template-columns: 6rem 1fr; gap: clamp(1rem, 3vw, 2.5rem);
  padding-block: 1.6rem; border-top: 1px solid var(--line);
}
.news__year:last-child { border-bottom: 1px solid var(--line); }
.news__yr {
  font-family: var(--f-display); font-size: clamp(1.6rem, 3vw, 2.2rem); font-weight: 500;
  color: var(--ink); line-height: 1;
}
.news__items { list-style: none; margin: 0; padding: 0; display: grid; gap: 1.05rem; }
.news__items li { display: grid; grid-template-columns: 5.2rem 1fr; gap: 1rem; align-items: baseline; }
.news__date {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.02em;
  color: var(--graphite); text-transform: uppercase; padding-top: 0.15rem;
}
.news__body { margin: 0; max-width: 62ch; color: var(--ink-soft); }
.news__body strong { color: var(--ink); }
/* 雾蓝 highlight for a featured item */
.news__hi {
  background: var(--mist); border-left: 3px solid var(--indigo);
  border-radius: 0 6px 6px 0; padding: 0.9rem 1.1rem !important;
  margin-left: -0.4rem;
}
.news__hi .news__date { padding-top: 0; }
@media (max-width: 560px) {
  .news__year { grid-template-columns: 1fr; gap: 0.9rem; }
  .news__items li { grid-template-columns: 1fr; gap: 0.15rem; }
}

/* =========================================================================
   Research projects
   ========================================================================= */
.projects { display: grid; gap: clamp(2.5rem, 5vw, 4.5rem); }
.project {
  display: grid; grid-template-columns: 1.05fr 1fr; gap: clamp(1.5rem, 4vw, 3.5rem);
  align-items: center;
}
.project:nth-child(even) .project__media { order: 2; }
.project__media {
  position: relative; border-radius: 4px; overflow: hidden;
  background: var(--sand); border: 1px solid var(--line);
  box-shadow: 0 24px 50px -34px var(--shadow);
}
.project__media img { width: 100%; aspect-ratio: 16/10; object-fit: cover; transition: transform 0.7s var(--ease); }
.project:hover .project__media img { transform: scale(1.035); }
.project__media--empty {
  aspect-ratio: 16/10; display: grid; place-items: center;
  background:
    repeating-linear-gradient(45deg, var(--line-soft) 0 1px, transparent 1px 12px), var(--sand);
}
.project__media--empty span {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--graphite);
  border: 1px dashed var(--line); border-radius: 100px; padding: 0.4rem 0.9rem; background: var(--paper);
}
.project__span {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.1em;
  text-transform: uppercase; color: var(--graphite); margin-bottom: 0.7rem; display: block;
}
.project__title { margin-bottom: 0.7rem; }
.project__desc { color: var(--ink-soft); margin-bottom: 0.9rem; }
.project__more {
  font-family: var(--f-mono); font-size: 0.74rem; letter-spacing: 0.02em;
  text-decoration: none; color: var(--indigo); display: inline-flex; gap: 0.4rem; align-items: center;
  transition: color 0.2s;
}
.project__more::after { content: "→"; transition: transform 0.25s var(--ease); }
.project__more:hover { color: var(--gold-ink); }
.project__more:hover::after { transform: translateX(4px); }
@media (max-width: 780px) {
  .project { grid-template-columns: 1fr; gap: 1.3rem; }
  .project:nth-child(even) .project__media { order: 0; }
}

/* =========================================================================
   About page
   ========================================================================= */
.about__grid { display: grid; grid-template-columns: 1fr 1.4fr; gap: clamp(2rem, 5vw, 4rem); align-items: start; }
.about__media { position: relative; }
.about__media img { width: 100%; border-radius: 4px; box-shadow: 0 26px 55px -34px var(--shadow); }
.about__card {
  background: var(--sand); border: 1px solid var(--line); border-radius: 6px;
  padding: 1.4rem 1.5rem; margin-top: 1.2rem;
}
.about__card h4 { font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.13em; text-transform: uppercase; color: var(--graphite); margin-bottom: 0.8rem; font-weight: 500; }
.factlist { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.7rem; }
.factlist li { display: grid; grid-template-columns: 1.2rem 1fr; gap: 0.6rem; font-size: 0.95rem; color: var(--ink-soft); }
.factlist li span:first-child { color: var(--gold-ink); }
.factlist li b { color: var(--ink); font-weight: 600; }
.interests { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.4rem; }
.tag {
  font-family: var(--f-mono); font-size: 0.7rem; letter-spacing: 0.01em;
  border: 1px solid var(--line); border-radius: 100px; padding: 0.35rem 0.85rem; color: var(--ink-soft);
}

@media (max-width: 780px) { .about__grid { grid-template-columns: 1fr; } }

/* =========================================================================
   CV page
   ========================================================================= */
.cv { display: grid; gap: clamp(2.4rem, 5vw, 3.6rem); }
.cv__block { display: grid; grid-template-columns: 12rem 1fr; gap: clamp(1rem, 3vw, 2.5rem); }
.cv__label {
  font-family: var(--f-mono); font-size: 0.73rem; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--ink); padding-top: 0.35rem; font-weight: 500;
  align-self: start; position: sticky; top: 5rem;
}
.cv__label::before {
  content: ""; display: block; width: 22px; height: 2px; background: var(--gold);
  margin-bottom: 0.6rem;
}
.cv__items { display: grid; gap: 1.4rem; margin: 0; padding: 0; }
.entry { display: grid; gap: 0.15rem; }
.entry__top { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 0.4rem 1rem; align-items: baseline; }
.entry__role { font-family: var(--f-display); font-size: 1.2rem; font-weight: 500; color: var(--ink); }
.entry__when { font-family: var(--f-mono); font-size: 0.72rem; color: var(--graphite); letter-spacing: 0.01em; white-space: nowrap; }
.entry__meta { color: var(--ink-soft); font-size: 0.95rem; }
.entry__note { color: var(--graphite); font-size: 0.9rem; }

/* publications */
.pubs { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.2rem; }
.pubs li {
  display: grid; grid-template-columns: 3.2rem 1fr; gap: 0.6rem;
  padding: 0.85rem 0.6rem; border-radius: 5px;
  border-bottom: 1px solid var(--line-soft);
  transition: background 0.25s;
}
.pubs li:hover { background: var(--sand); }
.pubs .tagcol { font-family: var(--f-mono); font-size: 0.7rem; color: var(--graphite); padding-top: 0.2rem; letter-spacing: 0.02em; }
.pubs .cite { margin: 0; color: var(--ink-soft); font-size: 0.96rem; line-height: 1.5; max-width: none; }
.pubs .cite b { color: var(--ink); }
.pubs .cite .venue { font-style: italic; color: var(--ink); }
.pubs .cite .status { color: var(--graphite); font-family: var(--f-mono); font-size: 0.76rem; }

@media (max-width: 680px) {
  .cv__block { grid-template-columns: 1fr; gap: 0.9rem; }
  .cv__label { position: static; }
}
.simple { list-style: none; margin: 0; padding: 0; display: grid; gap: 0.6rem; }
.simple li { display: grid; grid-template-columns: 1fr auto; gap: 0.5rem 1rem; align-items: baseline; padding-bottom: 0.5rem; border-bottom: 1px solid var(--line-soft); color: var(--ink-soft); }
.simple li span { font-family: var(--f-mono); font-size: 0.7rem; color: var(--graphite); white-space: nowrap; }

/* =========================================================================
   Gallery
   ========================================================================= */
.gallery { columns: 3 260px; column-gap: 1rem; }
.gitem {
  break-inside: avoid; margin-bottom: 1rem; position: relative;
  border-radius: 4px; overflow: hidden; background: var(--sand);
  border: 1px solid var(--line); cursor: default;
}
.gitem img { width: 100%; transition: transform 0.7s var(--ease); }
.gitem:hover img { transform: scale(1.05); }
.gitem figcaption {
  position: absolute; inset: auto 0 0 0;
  padding: 1.6rem 0.9rem 0.75rem; margin: 0;
  font-family: var(--f-mono); font-size: 0.7rem; line-height: 1.45; letter-spacing: 0.005em;
  color: #fff;
  background: linear-gradient(transparent, rgba(10, 15, 20, 0.86));
  transform: translateY(0.6rem); opacity: 0;
  transition: transform 0.4s var(--ease), opacity 0.35s;
}
.gitem:hover figcaption, .gitem:focus-within figcaption { transform: translateY(0); opacity: 1; }
@media (hover: none) {
  .gitem figcaption { transform: none; opacity: 1; }
}

/* =========================================================================
   Footer
   ========================================================================= */
.footer { border-top: 1px solid var(--line); margin-top: 2rem; background: var(--sand); }
.footer__inner {
  max-width: var(--maxw); margin-inline: auto; padding: clamp(2.5rem, 5vw, 3.5rem) var(--gut);
  display: grid; grid-template-columns: 1fr auto; gap: 1.5rem 2rem; align-items: end;
}
.footer__name { font-family: var(--f-display); font-size: 1.5rem; font-weight: 500; margin-bottom: 0.4rem; }
.footer__links { display: flex; flex-wrap: wrap; gap: 0.7rem; }
.footer__links a {
  display: inline-flex; align-items: center; gap: 0.45rem;
  font-family: var(--f-mono); font-size: 0.74rem; text-decoration: none; color: var(--ink-soft);
  border: 1px solid var(--line); border-radius: 100px; padding: 0.45rem 0.85rem;
  transition: color 0.2s, border-color 0.2s, transform 0.2s var(--ease);
}
.footer__links a:hover { color: var(--indigo); border-color: var(--indigo); transform: translateY(-2px); }
.footer__links svg { width: 15px; height: 15px; }
.footer__meta { font-family: var(--f-mono); font-size: 0.7rem; color: var(--graphite); }
@media (max-width: 620px) { .footer__inner { grid-template-columns: 1fr; align-items: start; } }

/* =========================================================================
   Scroll reveal
   ========================================================================= */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity 0.7s var(--ease), transform 0.7s var(--ease); }
.reveal.in { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
  .reveal { opacity: 1; transform: none; }
}

/* utilities */
.divider { height: 1px; background: var(--line); border: 0; margin: 0; }
.center { text-align: center; }
.mt-0 { margin-top: 0; }