/* ===================================================================
   Ning Qi — academic homepage
   Design: modern-academic. Serif display (Fraunces) + Inter body.
   Light/dark via [data-theme]. Single accent: deep academic blue.
   =================================================================== */

:root {
  --bg: #fbfbfd;
  --bg-soft: #f1f3f8;
  --card: #ffffff;
  --ink: #16202e;
  --ink-2: #4a5568;
  --ink-3: #8b95a5;
  --accent: #0d4ea6;
  --accent-2: #0a7d8c;
  --accent-soft: #e7eefb;
  --line: #e3e7ef;
  --badge-award-bg: #fff4e0;
  --badge-award-ink: #9a6200;
  --badge-ur-bg: #eef2f7;
  --badge-ur-ink: #5a6b82;
  --shadow: 0 1px 2px rgba(22, 32, 46, .05), 0 8px 28px rgba(22, 32, 46, .07);
  --radius: 14px;
}

[data-theme="dark"] {
  --bg: #0e141e;
  --bg-soft: #131b28;
  --card: #172130;
  --ink: #e8edf5;
  --ink-2: #aab6c8;
  --ink-3: #6d7a8f;
  --accent: #6ea8ff;
  --accent-2: #4fc3d4;
  --accent-soft: #1b2a44;
  --line: #263349;
  --badge-award-bg: #33280f;
  --badge-award-ink: #ffc862;
  --badge-ur-bg: #1d2735;
  --badge-ur-ink: #93a3b8;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 10px 30px rgba(0, 0, 0, .35);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: "Inter", -apple-system, "Segoe UI", "PingFang SC", sans-serif;
  font-size: 15.5px;
  line-height: 1.62;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}
h1, h2, h3, .serif {
  font-family: "Fraunces", Georgia, "Times New Roman", serif;
  font-weight: 600;
  letter-spacing: -.01em;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
img { max-width: 100%; }
.wrap { max-width: 1060px; margin: 0 auto; padding: 0 22px; }

/* ---------- top nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: blur(14px);
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  display: flex; align-items: center; gap: 18px;
  height: 56px;
}
.nav-name { font-weight: 700; font-size: 16px; color: var(--ink); white-space: nowrap; }
.nav-name:hover { text-decoration: none; }
.nav-links { display: flex; gap: 2px; margin-left: auto; overflow-x: auto; }
.nav-links a {
  padding: 6px 11px; border-radius: 8px;
  color: var(--ink-2); font-size: 13.5px; font-weight: 500; white-space: nowrap;
}
.nav-links a:hover { background: var(--bg-soft); text-decoration: none; color: var(--ink); }
.nav-links a.active { color: var(--accent); background: var(--accent-soft); }
.theme-btn {
  border: 1px solid var(--line); background: var(--card); color: var(--ink-2);
  width: 34px; height: 34px; border-radius: 50%; cursor: pointer; flex: none;
  font-size: 15px; line-height: 1;
}
.theme-btn:hover { color: var(--ink); }

/* ---------- hero ---------- */
.hero { padding: 58px 0 40px; }
.hero-grid { display: grid; grid-template-columns: 240px 1fr; gap: 42px; align-items: center; }
.portrait {
  width: 240px; height: 240px; object-fit: cover; border-radius: 22px;
  box-shadow: var(--shadow);
  outline: 6px solid color-mix(in srgb, var(--accent) 10%, transparent);
}
.hello { color: var(--accent); font-weight: 600; font-size: 14px; letter-spacing: .12em; text-transform: uppercase; margin: 0 0 6px; }
.hero h1 { font-size: 46px; margin: 0 0 6px; line-height: 1.1; }
.hero h1 .zh { font-weight: 500; color: var(--ink-3); font-size: 30px; margin-left: 10px; }
.role { color: var(--ink-2); font-size: 16.5px; margin: 0 0 14px; }
.role b { color: var(--ink); font-weight: 600; }
.bio { color: var(--ink-2); max-width: 640px; margin: 0 0 18px; }
.bio strong { color: var(--ink); }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 20px; }
.chip {
  background: var(--card); border: 1px solid var(--line); border-radius: 999px;
  padding: 5px 13px; font-size: 13px; color: var(--ink-2); box-shadow: 0 1px 2px rgba(22,32,46,.04);
}
.chip b { color: var(--accent); font-weight: 700; }

.btns { display: flex; flex-wrap: wrap; gap: 9px; }
.btn {
  display: inline-flex; align-items: center; gap: 7px;
  padding: 8px 15px; border-radius: 10px; font-size: 13.5px; font-weight: 600;
  border: 1px solid var(--line); background: var(--card); color: var(--ink-2);
  transition: transform .12s ease, box-shadow .12s ease;
}
.btn:hover { text-decoration: none; transform: translateY(-1px); box-shadow: var(--shadow); color: var(--ink); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { color: #fff; }

/* ---------- sections ---------- */
section { padding: 44px 0 10px; }
.eyebrow { color: var(--accent-2); font-weight: 700; font-size: 12.5px; letter-spacing: .14em; text-transform: uppercase; margin: 0 0 4px; }
section h2 { font-size: 30px; margin: 0 0 18px; }
.section-note { color: var(--ink-3); font-size: 13.5px; margin: -10px 0 16px; }

/* news */
.news { display: grid; gap: 0; border-left: 2px solid var(--line); padding-left: 0; margin: 0; list-style: none; }
.news li { position: relative; padding: 7px 0 7px 24px; color: var(--ink-2); }
.news li::before {
  content: ""; position: absolute; left: -6px; top: 16px;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--accent); outline: 3px solid var(--accent-soft);
}
.news .date { font-weight: 700; color: var(--ink); font-size: 13px; margin-right: 8px; font-variant-numeric: tabular-nums; }

/* publication filters */
.filters { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 18px; }
.filter {
  border: 1px solid var(--line); background: var(--card); color: var(--ink-2);
  border-radius: 999px; padding: 6px 15px; font-size: 13.5px; font-weight: 600; cursor: pointer;
}
.filter:hover { color: var(--ink); }
.filter.active { background: var(--accent); border-color: var(--accent); color: #fff; }
.count { opacity: .65; font-weight: 500; margin-left: 4px; }

.publist { list-style: none; margin: 0; padding: 0; }
.pub {
  display: grid; grid-template-columns: 64px 1fr; gap: 16px;
  padding: 13px 14px; border-radius: var(--radius); margin-bottom: 4px;
}
.pub:hover { background: var(--bg-soft); }
.pub .year {
  color: var(--ink-3); font-weight: 700; font-size: 13.5px; padding-top: 2px;
  font-variant-numeric: tabular-nums;
}
.pub .cite { color: var(--ink-2); }
.pub .cite .me { font-weight: 700; color: var(--ink); }
.pub .cite .title { color: var(--ink); font-weight: 600; }
.pub .cite .venue { font-style: italic; }
.badge {
  display: inline-block; border-radius: 6px; padding: 1.5px 8px; font-size: 11.5px; font-weight: 700;
  vertical-align: 1px; margin-left: 6px; white-space: nowrap;
}
.badge.award { background: var(--badge-award-bg); color: var(--badge-award-ink); }
.badge.ur { background: var(--badge-ur-bg); color: var(--badge-ur-ink); }
.badge.cn { background: var(--accent-soft); color: var(--accent); }
.pub.hidden { display: none; }

/* grants */
.cards { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 15px 17px; box-shadow: 0 1px 2px rgba(22,32,46,.03);
}
.card .role-chip {
  display: inline-block; font-size: 11.5px; font-weight: 700; letter-spacing: .04em;
  color: var(--accent); background: var(--accent-soft); border-radius: 6px; padding: 2px 8px; margin-bottom: 7px;
}
.card .g-title { font-weight: 600; color: var(--ink); margin: 0 0 5px; line-height: 1.45; }
.card .g-meta { color: var(--ink-3); font-size: 13px; }

/* talks timeline */
.talks { list-style: none; margin: 0; padding: 0; }
.talks li {
  display: grid; grid-template-columns: 86px 1fr; gap: 16px; padding: 9px 12px; border-radius: 12px;
}
.talks li:hover { background: var(--bg-soft); }
.talks .t-date { color: var(--ink-3); font-weight: 700; font-size: 13px; padding-top: 3px; font-variant-numeric: tabular-nums; }
.talks .t-title { font-weight: 600; color: var(--ink); }
.talks .t-venue { color: var(--ink-2); font-size: 14px; }
.slides-link {
  font-size: 12px; font-weight: 700; margin-left: 8px;
  border: 1px solid var(--line); border-radius: 6px; padding: 1px 8px; vertical-align: 1px;
}
.slides-link:hover { background: var(--accent-soft); text-decoration: none; }

/* teaching / advising / service */
.twocol { display: grid; grid-template-columns: 1fr 1fr; gap: 26px; }
.sub h3 { font-size: 18px; margin: 4px 0 10px; color: var(--ink); }
.plain { list-style: none; margin: 0; padding: 0; }
.plain li { padding: 5px 0 5px 18px; position: relative; color: var(--ink-2); }
.plain li::before { content: "▸"; position: absolute; left: 0; color: var(--accent); font-size: 12px; top: 8px; }
.plain b { color: var(--ink); font-weight: 600; }
.plain .muted { color: var(--ink-3); font-size: 13px; }

/* honors */
.honors { columns: 2; column-gap: 30px; list-style: none; margin: 0; padding: 0; }
.honors li {
  break-inside: avoid; display: flex; justify-content: space-between; gap: 12px;
  padding: 6.5px 2px; border-bottom: 1px dashed var(--line); color: var(--ink-2);
}
.honors .hy { color: var(--ink-3); font-weight: 700; font-size: 13px; white-space: nowrap; font-variant-numeric: tabular-nums; }

/* ---------- research highlight cards (home) ---------- */
.hl-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 13px; }
.hl-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px 17px 14px; box-shadow: 0 1px 2px rgba(22,32,46,.03);
  display: flex; flex-direction: column; gap: 8px;
  transition: transform .14s ease, box-shadow .14s ease;
}
.hl-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.venue-chip {
  align-self: flex-start; font-size: 11px; font-weight: 800; letter-spacing: .05em;
  text-transform: uppercase; color: var(--accent); background: var(--accent-soft);
  border-radius: 6px; padding: 3px 9px;
}
.venue-chip.gold { color: var(--badge-award-ink); background: var(--badge-award-bg); }
.hl-title { font-weight: 650; color: var(--ink); line-height: 1.42; font-size: 14.5px; margin: 0; }
.hl-meta { color: var(--ink-3); font-size: 12.5px; margin: 0; }
.hl-meta .me { color: var(--ink-2); font-weight: 700; }

/* explore cards */
.explore { display: grid; grid-template-columns: repeat(4, 1fr); gap: 13px; }
.explore a {
  display: block; background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 18px; color: var(--ink); font-weight: 600;
  transition: transform .14s ease, box-shadow .14s ease;
}
.explore a:hover { transform: translateY(-3px); box-shadow: var(--shadow); text-decoration: none; }
.explore .num { display: block; font-size: 30px; color: var(--accent); font-family: "Fraunces", serif; }
.explore .lbl { color: var(--ink-2); font-size: 13.5px; font-weight: 500; }

/* sub-page header */
.page-head { padding: 44px 0 6px; }
.page-head h1 { font-size: 38px; margin: 0 0 8px; }
.page-head p { color: var(--ink-2); margin: 0; max-width: 720px; }
.group-head {
  font-size: 21px; margin: 30px 0 10px; color: var(--ink);
  display: flex; align-items: baseline; gap: 10px;
}
.group-head .count { color: var(--ink-3); font-size: 13.5px; font-weight: 600; }

@media (max-width: 820px) {
  .hl-grid, .explore { grid-template-columns: 1fr; }
}

/* footer */
footer { margin-top: 56px; border-top: 1px solid var(--line); padding: 26px 0 40px; color: var(--ink-3); font-size: 13.5px; }
.foot-inner { display: flex; flex-wrap: wrap; gap: 12px; justify-content: space-between; }

/* responsive */
@media (max-width: 820px) {
  .hero-grid { grid-template-columns: 1fr; text-align: center; gap: 22px; }
  .portrait { margin: 0 auto; width: 190px; height: 190px; }
  .bio { margin-left: auto; margin-right: auto; }
  .chips, .btns { justify-content: center; }
  .cards, .twocol { grid-template-columns: 1fr; }
  .honors { columns: 1; }
  .hero h1 { font-size: 34px; }
  .nav-inner { gap: 8px; }
}