/* =========================================================
   IS2 Lab — modern site styles
   Design: clean technical-grid + editorial whitespace
   Accent: ZJU blue ("求是蓝"); full light/dark support
   ========================================================= */

:root {
  --ink:        #15202e;
  --ink-soft:   #45505f;
  --ink-faint:  #71808f;
  --bg:         #ffffff;
  --bg-soft:    #f4f7fb;
  --bg-card:    #ffffff;
  --line:       #e2e8f0;
  --line-soft:  #eef2f8;
  --teal:       #003f88;
  --teal-bright:#1e75d3;
  --teal-ink:   #00295c;
  --teal-wash:  #e4eefb;
  --blue:       #0d7d83;
  --blue-wash:  #e0f3f3;
  --violet:     #6d4bb6;
  --violet-wash:#efe9fb;
  --maxw:       1120px;
  --radius:     14px;
  --radius-sm:  9px;
  --shadow:     0 1px 2px rgba(15,28,48,.05), 0 8px 30px rgba(15,28,48,.07);
  --font-sans:  "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --font-mono:  "JetBrains Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --font-cjk:   "Inter", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}

[data-theme="dark"] {
  --ink:        #e6edf5;
  --ink-soft:   #a7b4c4;
  --ink-faint:  #7b8a9c;
  --bg:         #0b1016;
  --bg-soft:    #111722;
  --bg-card:    #121a24;
  --line:       #233044;
  --line-soft:  #1a2330;
  --teal:       #5fa2f0;
  --teal-bright:#7fb6f5;
  --teal-ink:   #bcd9ff;
  --teal-wash:  #11233f;
  --blue:       #43c9c2;
  --blue-wash:  #0f2b2b;
  --violet:     #b69bef;
  --violet-wash:#221a39;
  --shadow:     0 1px 2px rgba(0,0,0,.3), 0 8px 30px rgba(0,0,0,.35);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--ink);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background .25s ease, color .25s ease;
}

html[lang="zh"] body { font-family: var(--font-cjk); }

a { color: var(--teal); text-decoration: none; }
a:hover { text-decoration: underline; }

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

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

.mono { font-family: var(--font-mono); }

/* ---------- top nav ---------- */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(140%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  max-width: var(--maxw); margin: 0 auto; padding: 0 28px;
  height: 64px; display: flex; align-items: center; justify-content: space-between; gap: 18px;
}
.brand { display: flex; align-items: center; gap: 11px; font-weight: 600; letter-spacing: -.01em; color: var(--ink); }
.brand .mark {
  font-family: var(--font-mono); font-weight: 700; font-size: 15px;
  background: var(--teal); color: #fff; padding: 5px 9px; border-radius: 8px; line-height: 1;
}
.brand .mark sup { font-size: .7em; }
.brand .bt { font-size: 15.5px; }
.brand .bs { display:block; font-size: 11px; font-weight: 500; color: var(--ink-faint); letter-spacing: .02em; margin-top: -3px;}

.nav-links { display: flex; align-items: center; gap: 4px; }
.nav-links a {
  color: var(--ink-soft); font-size: 14.5px; font-weight: 500;
  padding: 8px 13px; border-radius: 8px; transition: .15s;
}
.nav-links a:hover { background: var(--bg-soft); color: var(--ink); text-decoration: none; }
.nav-links a.active { color: var(--teal); }

.nav-tools { display: flex; align-items: center; gap: 8px; }
.btn-ghost {
  font: inherit; font-size: 13px; font-weight: 600; cursor: pointer;
  background: transparent; color: var(--ink-soft);
  border: 1px solid var(--line); border-radius: 9px; padding: 7px 11px;
  display: inline-flex; align-items: center; gap: 6px; transition: .15s;
}
.btn-ghost:hover { border-color: var(--teal); color: var(--teal); }
.lang-btn .on { color: var(--teal); }
.lang-btn .sep { color: var(--ink-faint); margin: 0 1px; }

.nav-burger { display: none; background: none; border: 1px solid var(--line); border-radius: 9px; padding: 8px 10px; cursor: pointer; color: var(--ink); }

@media (max-width: 820px) {
  .nav-links {
    position: absolute; top: 64px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: var(--bg); border-bottom: 1px solid var(--line);
    padding: 8px; display: none;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 12px 14px; border-radius: 8px; }
  .nav-burger { display: inline-flex; }
}

/* ---------- hero ---------- */
.hero {
  position: relative; overflow: hidden;
  border-bottom: 1px solid var(--line);
  background:
    radial-gradient(900px 400px at 85% -10%, color-mix(in srgb, var(--teal) 12%, transparent), transparent 70%),
    var(--bg);
}
.hero-grid {
  position: absolute; inset: 0; pointer-events: none; opacity: .5;
  background-image:
    linear-gradient(var(--line-soft) 1px, transparent 1px),
    linear-gradient(90deg, var(--line-soft) 1px, transparent 1px);
  background-size: 46px 46px;
  -webkit-mask-image: radial-gradient(800px 360px at 70% 0%, #000, transparent 75%);
          mask-image: radial-gradient(800px 360px at 70% 0%, #000, transparent 75%);
}
.hero-inner { position: relative; max-width: var(--maxw); margin: 0 auto; padding: 78px 28px 70px; }
.eyebrow {
  font-family: var(--font-mono); font-size: 12.5px; letter-spacing: .06em;
  color: var(--teal); text-transform: lowercase; margin-bottom: 18px;
  display: inline-flex; align-items: center; gap: 8px;
}
.eyebrow::before { content:""; width: 22px; height: 1px; background: var(--teal); display:inline-block; }
.hero h1 {
  margin: 0 0 18px; font-size: clamp(30px, 5vw, 50px); line-height: 1.08;
  letter-spacing: -.025em; font-weight: 700; max-width: 22ch; text-wrap: balance;
}
.hero h1 .hl { color: var(--teal-bright); }
.hero .lede { font-size: clamp(16px, 2vw, 19px); color: var(--ink-soft); max-width: 60ch; margin: 0 0 26px; }
.pillrow { display: flex; flex-wrap: wrap; gap: 9px; margin-bottom: 30px; }
.pill {
  font-size: 13px; font-weight: 500; padding: 7px 14px; border-radius: 999px;
  background: var(--teal-wash); color: var(--teal-ink); border: 1px solid color-mix(in srgb, var(--teal) 22%, transparent);
}
.hero-cta { display: flex; flex-wrap: wrap; gap: 12px; }
.btn {
  display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
  font: inherit; font-size: 14.5px; font-weight: 600; padding: 11px 20px; border-radius: 11px;
  border: 1px solid transparent; transition: .16s;
}
.btn-primary { background: var(--teal); color: #fff; }
.btn-primary:hover { background: var(--teal-ink); text-decoration: none; }
[data-theme="dark"] .btn-primary { color: #08203a; }
.btn-line { background: transparent; color: var(--ink); border-color: var(--line); }
.btn-line:hover { border-color: var(--teal); color: var(--teal); text-decoration: none; }

/* ---------- generic sections ---------- */
section { padding: 64px 0; }
.section-soft { background: var(--bg-soft); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.sec-head { margin-bottom: 36px; }
.sec-kicker { font-family: var(--font-mono); font-size: 12.5px; letter-spacing: .05em; color: var(--teal); margin: 0 0 8px; }
.sec-title { font-size: clamp(24px, 3.4vw, 33px); letter-spacing: -.02em; font-weight: 700; margin: 0; line-height: 1.15; }
.sec-sub { color: var(--ink-soft); max-width: 70ch; margin: 12px 0 0; font-size: 16.5px; }

h1,h2,h3,h4 { color: var(--ink); }

/* ---------- about / topics ---------- */
.topic-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 8px; }
.topic {
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 22px 24px; box-shadow: var(--shadow);
}
.topic .ic { width: 40px; height: 40px; border-radius: 10px; background: var(--teal-wash); color: var(--teal); display:flex; align-items:center; justify-content:center; font-size: 20px; margin-bottom: 14px; }
.topic h3 { margin: 0 0 7px; font-size: 17px; letter-spacing: -.01em; }
.topic p { margin: 0; color: var(--ink-soft); font-size: 14.5px; }

/* ---------- stats band ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 14px; }
.stat { background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius); padding: 22px 20px; text-align: left; }
.stat .n { font-size: 34px; font-weight: 700; letter-spacing: -.03em; color: var(--teal); line-height: 1; }
.stat .l { margin-top: 8px; font-size: 13.5px; color: var(--ink-soft); }

/* ---------- two column ---------- */
.cols2 { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.panel { background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius); padding: 26px; }
.panel h3 { margin: 0 0 12px; font-size: 19px; }
.panel p { margin: 0 0 12px; color: var(--ink-soft); }
.tagline { font-family: var(--font-mono); font-size: 13px; color: var(--ink-faint); }

/* ---------- news ---------- */
.news-list { display: flex; flex-direction: column; gap: 0; }
.news-item { display: grid; grid-template-columns: 130px 1fr; gap: 20px; padding: 18px 0; border-bottom: 1px solid var(--line-soft); }
.news-item:last-child { border-bottom: 0; }
.news-date { font-family: var(--font-mono); font-size: 13px; color: var(--teal); padding-top: 1px; }
.news-body { color: var(--ink-soft); font-size: 15.5px; }
.news-body em { color: var(--ink); font-style: normal; font-weight: 500; }

/* ---------- team ---------- */
.team-block { margin-top: 30px; }
.team-block > h3 {
  font-size: 14px; font-family: var(--font-mono); letter-spacing: .05em;
  color: var(--teal); margin: 38px 0 18px; padding-bottom: 10px; border-bottom: 1px solid var(--line);
  display: flex; align-items: baseline; gap: 10px;
}
.team-block > h3 .cnt { color: var(--ink-faint); font-weight: 400; }
.people { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.person {
  background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; box-shadow: var(--shadow); transition: .18s;
}
.person:hover { transform: translateY(-3px); border-color: color-mix(in srgb, var(--teal) 40%, var(--line)); }
.person .ph { aspect-ratio: 1/1; background: var(--bg-soft); overflow: hidden; }
.person .ph img { width: 100%; height: 100%; object-fit: cover; }
.person .meta { padding: 14px 15px 16px; }
.person .nm { font-weight: 600; font-size: 15.5px; letter-spacing: -.01em; }
.person .role { font-size: 12.5px; color: var(--teal); margin-top: 2px; font-weight: 500; }
.person ul { margin: 9px 0 0; padding-left: 16px; }
.person li { font-size: 12.5px; color: var(--ink-soft); line-height: 1.5; margin-bottom: 2px; }

.faculty-card { grid-column: span 4; display: grid; grid-template-columns: 200px 1fr; gap: 0; }
.faculty-card .ph { aspect-ratio: auto; height: 100%; min-height: 220px; }
.faculty-card .meta { padding: 26px 28px; }
.faculty-card .nm { font-size: 23px; }
.faculty-card .role { font-size: 14px; margin: 4px 0 12px; }
.faculty-card li { font-size: 14px; }
.faculty-card .email { margin-top: 12px; font-size: 13.5px; font-family: var(--font-mono); }

/* alumni table */
.tablewrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); margin-top: 22px; }
table.alumni { width: 100%; border-collapse: collapse; font-size: 14px; min-width: 640px; }
table.alumni th, table.alumni td { text-align: left; padding: 13px 18px; border-bottom: 1px solid var(--line-soft); vertical-align: top; }
table.alumni thead th { background: var(--bg-soft); font-family: var(--font-mono); font-size: 12px; letter-spacing: .04em; color: var(--ink-soft); font-weight: 600; }
table.alumni tr:last-child td { border-bottom: 0; }
table.alumni .who { font-weight: 600; color: var(--ink); white-space: nowrap; }
table.alumni .where { color: var(--teal); white-space: nowrap; }

/* ---------- research ---------- */
.track { background: var(--bg-card); border: 1px solid var(--line); border-radius: var(--radius); padding: 0; overflow: hidden; margin-bottom: 30px; box-shadow: var(--shadow); }
.track-head { padding: 28px 30px 22px; border-bottom: 1px solid var(--line); position: relative; }
.track-1 .track-head { background: var(--teal-wash); }
.track-2 .track-head { background: var(--blue-wash); }
.track-tag { font-family: var(--font-mono); font-size: 12px; letter-spacing: .05em; font-weight: 600; }
.track-1 .track-tag { color: var(--teal); }
.track-2 .track-tag { color: var(--blue); }
.track-head h3 { font-size: clamp(20px, 2.6vw, 26px); letter-spacing: -.02em; margin: 8px 0 12px; }
.track-quote { font-style: italic; color: var(--ink-soft); font-size: 14.5px; border-left: 3px solid; padding-left: 14px; margin: 0; }
.track-1 .track-quote { border-color: var(--teal); }
.track-2 .track-quote { border-color: var(--blue); }
.track-body { padding: 24px 30px 8px; }
.track-body p { margin: 0 0 18px; color: var(--ink-soft); }
.venues { display: flex; flex-wrap: wrap; gap: 7px; margin: 4px 0 22px; }
.venue { font-family: var(--font-mono); font-size: 11.5px; padding: 4px 9px; border-radius: 7px; background: var(--bg-soft); border: 1px solid var(--line); color: var(--ink-soft); }
.works { padding: 0 30px 28px; }
.works h4 { font-size: 13px; font-family: var(--font-mono); letter-spacing: .04em; color: var(--ink-faint); margin: 6px 0 14px; }
.work { display: grid; grid-template-columns: 92px 1fr; gap: 16px; padding: 14px 0; border-top: 1px solid var(--line-soft); }
.work .wv { font-family: var(--font-mono); font-size: 12px; font-weight: 600; }
.track-1 .work .wv { color: var(--teal); }
.track-2 .work .wv { color: var(--blue); }
.work .wt { font-size: 14.5px; color: var(--ink-soft); }
.work .wt b { color: var(--ink); font-weight: 600; }
.award { display:inline-block; margin-left: 6px; font-size: 11px; font-weight: 600; color: #854f0b; background: #faeeda; padding: 1px 7px; border-radius: 6px; }
[data-theme="dark"] .award { color: #fac775; background: #412402; }

/* third pillar accent */
.track-3 .track-head { background: var(--violet-wash); }
.track-3 .track-tag { color: var(--violet); }
.track-3 .track-quote { border-color: var(--violet); }
.track-1 .hl-venue { color: var(--teal); }
.track-2 .hl-venue { color: var(--blue); }
.track-3 .hl-venue { color: var(--violet); }
.track-1 .hl { border-top-color: var(--teal); }
.track-2 .hl { border-top-color: var(--blue); }
.track-3 .hl { border-top-color: var(--violet); }

/* highlight cards */
.hl-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.hl { background: var(--bg-soft); border: 1px solid var(--line); border-top: 3px solid var(--teal); border-radius: var(--radius-sm); padding: 16px 18px; display: flex; flex-direction: column; }
.hl-top { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; margin-bottom: 8px; }
.hl-venue { font-family: var(--font-mono); font-size: 11.5px; font-weight: 600; letter-spacing: .02em; }
.hl-top .award { margin-left: 0; }
.hl-title { font-weight: 600; color: var(--ink); font-size: 15px; line-height: 1.35; letter-spacing: -.01em; }
a.hl-title { text-decoration: none; display: block; }
a.hl-title:hover { text-decoration: underline; text-underline-offset: 2px; }
.hl-arrow { font-weight: 700; white-space: nowrap; }
.track-1 a.hl-title .hl-arrow { color: var(--teal); }
.track-2 a.hl-title .hl-arrow { color: var(--blue); }
.track-3 a.hl-title .hl-arrow { color: var(--violet); }
.hl-intro { margin: 8px 0 0; color: var(--ink-soft); font-size: 13.8px; line-height: 1.6; flex: 1; }
.hl-links { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 12px; }
.hl-links a { font-family: var(--font-mono); font-size: 12px; font-weight: 600; color: var(--teal); text-decoration: none; }
.track-2 .hl-links a { color: var(--blue); }
.track-3 .hl-links a { color: var(--violet); }
.hl-links a:hover { text-decoration: underline; }

/* sponsors / supported-by strip */
.sponsors-wrap { margin-top: 52px; text-align: center; }
.sponsors-h { font-family: var(--font-mono); font-size: 13px; letter-spacing: .04em; font-weight: 600; color: var(--ink-faint); margin: 0 0 20px; }
.sponsor-grid { display: flex; flex-wrap: wrap; gap: 16px; align-items: stretch; justify-content: center; }
.sponsor { display: flex; align-items: center; justify-content: center; min-width: 156px; height: 80px; padding: 14px 24px; background: #ffffff; border: 1px solid var(--line); border-radius: var(--radius-sm); box-shadow: var(--shadow); text-decoration: none; transition: border-color .15s ease, transform .15s ease; }
.sponsor:hover { border-color: var(--teal); transform: translateY(-2px); }
.sponsor-logo { max-height: 46px; max-width: 156px; object-fit: contain; display: block; }
.sponsor-name { display: none; align-items: center; justify-content: center; font-weight: 600; font-size: 15.5px; letter-spacing: -.01em; color: #23303a; text-align: center; }
[data-theme="dark"] .sponsor { border-color: #2b3a4d; }

/* vacancies page */
.vac-subhead { font-size: 13px; font-family: var(--font-mono); letter-spacing: .04em; color: var(--ink-faint); margin: 44px 0 16px; font-weight: 600; }
.vac-grid { grid-template-columns: repeat(3, 1fr); }
.vac-offers { margin: 0; padding: 0; list-style: none; }
.vac-offers li { position: relative; padding: 0 0 0 22px; margin: 0 0 12px; color: var(--ink-soft); font-size: 14.5px; line-height: 1.55; }
.vac-offers li:last-child { margin-bottom: 0; }
.vac-offers li::before { content: "→"; position: absolute; left: 0; top: 0; color: var(--teal); font-weight: 700; }
.vac-apply { margin-top: 24px; text-align: center; }
.vac-apply p { max-width: 68ch; margin: 0 auto 18px; }

/* ---------- publications ---------- */
.pub-cta { text-align: center; padding: 56px 30px; }

/* ---------- footer ---------- */
.foot { background: var(--bg-soft); border-top: 1px solid var(--line); padding: 52px 0 40px; }
.foot-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 34px; }
.foot h4 { font-size: 13px; font-family: var(--font-mono); letter-spacing: .05em; color: var(--teal); margin: 0 0 14px; }
.foot p, .foot a, .foot li { color: var(--ink-soft); font-size: 14px; }
.foot ul { list-style: none; margin: 0; padding: 0; }
.foot li { margin-bottom: 8px; }
.foot .lab { font-weight: 600; color: var(--ink); font-size: 15px; }
.foot-base { margin-top: 38px; padding-top: 22px; border-top: 1px solid var(--line); font-size: 13px; color: var(--ink-faint); display:flex; justify-content: space-between; flex-wrap: wrap; gap: 10px; }

/* ---------- carousel ---------- */

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .topic-grid { grid-template-columns: 1fr; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .cols2 { grid-template-columns: 1fr; }
  .people { grid-template-columns: repeat(2, 1fr); }
  .foot-grid { grid-template-columns: 1fr; }
  .faculty-card { grid-template-columns: 1fr; }
  .faculty-card .ph { min-height: 280px; aspect-ratio: 16/10; }
  .hl-grid { grid-template-columns: 1fr; }
}
@media (max-width: 540px) {
  .people { grid-template-columns: 1fr 1fr; }
  .news-item { grid-template-columns: 1fr; gap: 4px; }
  .work { grid-template-columns: 1fr; gap: 3px; }
}

.noscript-note { background: var(--teal-wash); color: var(--teal-ink); padding: 14px; text-align: center; font-size: 14px; }