/* =========================================================================
   GNARC — Global Network for Ageing Research on China & Chinese Populations
   Design system: modern minimalist. Warm paper, near-black ink, oxblood accent,
   hairline grid. Bilingual (EN / 中文). No external dependencies.
   ========================================================================= */

:root {
  /* Palette */
  --paper:      #ffffff;   /* clean white background           */
  --paper-2:    #f6f6f4;   /* slightly deeper panel            */
  --ink:        #191919;   /* near-black text                  */
  --ink-soft:   #3a3733;
  --muted:      #6e6a63;   /* secondary text                   */
  --accent:     #8a1c24;   /* oxblood — the single brand accent */
  --accent-ink: #6f141b;
  --line:       rgba(25, 25, 25, 0.14);  /* hairlines          */
  --line-soft:  rgba(25, 25, 25, 0.08);
  --white:      #ffffff;

  /* Type */
  --sans: "Helvetica Neue", -apple-system, BlinkMacSystemFont, "Segoe UI",
          Roboto, Arial, "PingFang SC", "Hiragino Sans GB",
          "Microsoft YaHei", "微软雅黑", sans-serif;

  /* Metrics */
  --maxw: 1180px;
  --gutter: clamp(20px, 5vw, 64px);
  --nav-h: 68px;
}

/* ------------------------------------------------------------------ reset */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.62;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { font-weight: 700; line-height: 1.12; letter-spacing: -0.01em; margin: 0; text-wrap: balance; }
p { margin: 0 0 1em; }
:lang(zh), [lang="zh"] { letter-spacing: 0; }

/* ---------------------------------------------------------------- layout */
.wrap { max-width: var(--maxw); margin: 0 auto; padding-inline: var(--gutter); }
:target, [id] { scroll-margin-top: calc(var(--nav-h) + 24px); }
.section { padding-block: clamp(56px, 8vw, 104px); }
.section--tight { padding-block: clamp(40px, 6vw, 72px); }
.divider { border: 0; border-top: 1px solid var(--line); margin: 0; }

/* small-caps eyebrow label */
.eyebrow {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 18px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.eyebrow::before {
  content: "";
  width: 10px; height: 10px;
  background: var(--accent);
  display: inline-block;
  flex: none;
}

.section-title { font-size: clamp(26px, 3.4vw, 40px); max-width: 20ch; }
.lead { font-size: clamp(18px, 2vw, 21px); color: var(--ink-soft); max-width: 62ch; }

/* ------------------------------------------------------------ top nav bar */
.nav {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255, 255, 255, 0.86);
  backdrop-filter: saturate(1.2) blur(10px);
  border-bottom: 1px solid var(--line);
  transition: box-shadow .3s;
}
.nav.scrolled { box-shadow: 0 6px 24px rgba(25,25,25,.07); }
.nav__inner {
  max-width: var(--maxw); margin: 0 auto;
  padding-inline: var(--gutter);
  height: var(--nav-h);
  display: flex; align-items: center; gap: 24px;
}
.brand { display: flex; align-items: center; gap: 12px; font-weight: 800; letter-spacing: 0.02em; }
.brand__mark { width: 26px; height: 26px; flex: none; color: var(--ink); }
.brand__name { font-size: 18px; }
.brand__name small { display:block; font-size: 10px; font-weight: 600; letter-spacing: .14em; color: var(--muted); text-transform: uppercase; margin-top: 2px;}

.nav__links { display: flex; align-items: center; gap: 2px; margin-left: auto; }
.nav__link, .nav__top {
  font-family: inherit; font-size: 14.5px; font-weight: 600; color: var(--ink-soft);
  padding: 8px 12px; border-radius: 2px; white-space: nowrap;
  background: none; border: 0; cursor: pointer; line-height: 1;
  display: inline-flex; align-items: center; gap: 6px;
  transition: color .15s, background .15s;
}
.nav__link:hover, .nav__top:hover { color: var(--ink); background: var(--line-soft); }
.nav__link[aria-current="page"], .nav__top[aria-current="page"] { color: var(--accent); }
.nav__caret { width: 9px; height: 6px; transition: transform .2s; opacity: .7; }

/* dropdown */
.nav__item { position: relative; }
.nav__item.open .nav__caret { transform: rotate(180deg); }
.nav__item.open .nav__top { color: var(--ink); background: var(--line-soft); }
.nav__menu {
  position: absolute; top: calc(100% + 8px); left: 0; min-width: 232px;
  background: var(--paper); border: 1px solid var(--line);
  box-shadow: 0 14px 34px rgba(25,25,25,.10);
  padding: 6px; opacity: 0; visibility: hidden; transform: translateY(-6px);
  transition: opacity .16s, transform .16s, visibility .16s; z-index: 60;
}
.nav__item.open .nav__menu { opacity: 1; visibility: visible; transform: translateY(0); }
.nav__sublink {
  display: block; padding: 9px 12px; font-size: 14px; font-weight: 600;
  color: var(--ink-soft); border-radius: 2px; white-space: nowrap;
  border-left: 2px solid transparent; transition: background .14s, color .14s, border-color .14s;
}
.nav__sublink:hover { background: var(--line-soft); color: var(--accent); border-left-color: var(--accent); }

.langtoggle {
  margin-left: 6px; border: 1px solid var(--line); background: transparent;
  font: inherit; font-size: 13px; font-weight: 700; color: var(--ink);
  padding: 6px 12px; cursor: pointer; border-radius: 2px; letter-spacing: .02em;
  transition: background .15s, border-color .15s;
}
.langtoggle:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }

.nav__toggle { display: none; margin-left: auto; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav__toggle span { display: block; width: 24px; height: 2px; background: var(--ink); margin: 5px 0; transition: .2s; }

/* ------------------------------------------------------------------- hero */
.hero {
  position: relative; overflow: hidden;
  border-bottom: 1px solid var(--line);
  background:
    repeating-linear-gradient(to right, transparent 0, transparent calc(12.5% - 1px),
      var(--line-soft) calc(12.5% - 1px), var(--line-soft) 12.5%);
}
.hero__inner { max-width: var(--maxw); margin: 0 auto; padding: clamp(56px,9vw,120px) var(--gutter) clamp(48px,7vw,96px); }
.hero__mark { width: 54px; height: 54px; color: var(--ink); margin-bottom: 30px; }
.hero h1 {
  font-size: clamp(34px, 6.4vw, 76px);
  line-height: 1.02; letter-spacing: -0.02em; max-width: 15ch;
}
.hero h1 .accent { color: var(--accent); }
.hero__sub { margin-top: 26px; font-size: clamp(17px, 2.1vw, 22px); color: var(--ink-soft); max-width: 54ch; }
.hero__meta {
  margin-top: 34px; padding-top: 22px; border-top: 1px solid var(--line);
  display: flex; flex-wrap: wrap; gap: 10px 26px; align-items: center;
  font-size: 12.5px; font-weight: 700; letter-spacing: .16em; text-transform: uppercase; color: var(--muted);
}
.hero__meta .dot { color: var(--accent); }

/* buttons */
.btn {
  display: inline-flex; align-items: center; gap: 9px;
  font-weight: 700; font-size: 15px; letter-spacing: .01em;
  padding: 13px 22px; border: 1px solid var(--ink); cursor: pointer;
  transition: background .18s, color .18s, transform .05s;
}
.btn:hover { background: var(--ink); color: var(--paper); }
.btn:active { transform: translateY(1px); }
.btn--accent { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn--accent:hover { background: var(--accent-ink); border-color: var(--accent-ink); color:#fff; }
.btn--ghost { border-color: var(--line); }
.btnrow { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 34px; }

/* --------------------------------------------------------------- grid kit */
.grid { display: grid; gap: 1px; background: var(--line); border: 1px solid var(--line); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.cell { background: var(--paper); padding: clamp(24px, 3vw, 38px); }
.cell h3 { font-size: 20px; margin-bottom: 10px; }
.cell__num { font-size: 12px; font-weight: 700; color: var(--accent); letter-spacing:.14em; }
.cell p { color: var(--muted); font-size: 15.5px; margin: 0; }

/* two-column prose layout (section label | body) */
.split { display: grid; grid-template-columns: minmax(0, 260px) minmax(0, 1fr); gap: clamp(24px, 5vw, 72px); align-items: start; }
.split__aside { position: sticky; top: calc(var(--nav-h) + 24px); }

/* --------------------------------------------------------------- news list */
.news { display: grid; gap: 0; border-top: 1px solid var(--line); }
.news__item {
  display: grid; grid-template-columns: 150px 1fr auto; gap: 20px; align-items: baseline;
  padding: 22px 0; border-bottom: 1px solid var(--line);
}
.news__date { font-size: 13px; font-weight: 700; letter-spacing: .06em; color: var(--muted); text-transform: uppercase; }
.news__title { font-size: 18px; font-weight: 700; }
.news__title span.tag { display:inline-block; font-size: 11px; font-weight: 700; color: var(--accent); border: 1px solid var(--accent); padding: 1px 7px; margin-left: 10px; vertical-align: middle; letter-spacing:.08em; text-transform: uppercase; }
.news__body { color: var(--muted); font-size: 15px; margin-top: 4px; }

/* --------------------------------------------------------------- events */
.year-block { border-top: 2px solid var(--ink); margin-top: 40px; padding-top: 8px; }
.year-block__head { font-size: 13px; font-weight: 800; letter-spacing: .2em; text-transform: uppercase; padding: 10px 0; }
.event {
  display: grid; grid-template-columns: 140px 1fr; gap: 8px 28px;
  padding: 22px 0; border-top: 1px solid var(--line);
}
.event__date { font-size: 13.5px; font-weight: 700; color: var(--accent); letter-spacing: .02em; padding-top: 3px; }
.event__title { font-size: 18.5px; font-weight: 700; line-height: 1.28; }
.event__speaker { color: var(--ink-soft); font-size: 15px; margin-top: 6px; }
.event__aff { color: var(--muted); font-size: 14px; margin-top: 2px; }
.event__loc { color: var(--muted); font-size: 13.5px; margin-top: 8px; display:flex; gap:7px; align-items:center;}
.event__loc::before{ content:"◈"; color: var(--accent); font-size:11px;}
.badge-sym { display:inline-block; font-size: 11px; font-weight: 700; color:#fff; background: var(--accent); padding: 1px 8px; margin-left: 8px; vertical-align: middle; letter-spacing: .06em; text-transform: uppercase; }

/* event rows that carry a poster image */
.event--poster { grid-template-columns: 140px 1fr 240px; align-items: start; }
.event__thumb {
  border: 1px solid var(--line); overflow: hidden; background: var(--paper-2);
}
.event__thumb img {
  width: 100%; aspect-ratio: 3 / 2; object-fit: cover; display: block;
  transition: transform .5s cubic-bezier(.16,1,.3,1);
}
.event--poster:hover .event__thumb img { transform: scale(1.04); }

/* homepage poster marquee — two large posters visible, auto-scrolling */
.postermarquee {
  position: relative; overflow: hidden;
  -webkit-mask-image: linear-gradient(to right, transparent, #000 6%, #000 94%, transparent);
          mask-image: linear-gradient(to right, transparent, #000 6%, #000 94%, transparent);
}
.postermarquee__track {
  display: flex; gap: 24px; width: max-content;
  animation: partners-scroll 45s linear infinite;
}
.postermarquee:hover .postermarquee__track { animation-play-state: paused; }
.postermarquee__item {
  flex: none;
  width: clamp(320px, 44vw, 620px);
  display: block; border: 1px solid var(--line); background: var(--paper);
  overflow: hidden;
  transition: box-shadow .4s;
}
.postermarquee__item:hover { box-shadow: 0 18px 40px rgba(25,25,25,.12); }
.postermarquee__item img {
  width: 100%; aspect-ratio: 3 / 2; object-fit: cover; display: block;
  transition: transform .5s cubic-bezier(.16,1,.3,1);
}
.postermarquee__item:hover img { transform: scale(1.03); }
.postermarquee__meta {
  display: block; padding: 13px 16px;
  font-size: 13.5px; font-weight: 600; color: var(--muted);
  border-top: 1px solid var(--line);
}
@media (prefers-reduced-motion: reduce) {
  .postermarquee__track { animation: none; flex-wrap: wrap; width: auto; }
  .postermarquee { mask-image: none; -webkit-mask-image: none; }
}
@media (max-width: 560px) {
  .postermarquee__item { width: 78vw; }
  .event--poster { grid-template-columns: 1fr; }
  .event__thumb { order: -1; max-width: 420px; }
}

/* --------------------------------------------------------------- members */
.people { display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.person { background: var(--paper); padding: 28px; text-align: center; display: flex; flex-direction: column; align-items: center; }
/* large square portrait, centred */
.person__avatar {
  width: 100%; max-width: 220px; aspect-ratio: 1 / 1; margin: 0 auto 20px;
  background: var(--paper-2); border: 1px solid var(--line);
  display: flex; align-items: center; justify-content: center;
  font-weight: 800; color: var(--accent); font-size: 40px; letter-spacing: .04em;
  overflow: hidden; flex: none;
}
.person__avatar--photo img { width: 100%; height: 100%; object-fit: cover; display: block; }
.person__name { font-size: 18px; font-weight: 700; }
.person__role { color: var(--accent); font-size: 13.5px; font-weight: 600; margin-top: 6px; }
.person__aff { color: var(--muted); font-size: 14px; margin-top: 6px; }
.person__mail { font-size: 13.5px; margin-top: 12px; word-break: break-all; }
.person__mail a { color: var(--ink); border-bottom: 1px solid var(--line); }
.person__mail a:hover { color: var(--accent); border-color: var(--accent); }

/* stat row */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.stat { background: var(--paper); padding: 30px 26px; }
.stat__num { font-size: clamp(30px, 4vw, 46px); font-weight: 800; letter-spacing: -0.02em; }
.stat__num .accent { color: var(--accent); }
.stat__label { font-size: 12.5px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; color: var(--muted); margin-top: 8px; }

/* partners — infinite marquee slider */
.partners {
  position: relative; overflow: hidden;
  border-block: 1px solid var(--line);
  padding-block: 34px;
  /* soft fade at both edges */
  -webkit-mask-image: linear-gradient(to right, transparent, #000 12%, #000 88%, transparent);
          mask-image: linear-gradient(to right, transparent, #000 12%, #000 88%, transparent);
}
.partners__track {
  display: flex; align-items: center; gap: clamp(48px, 7vw, 110px);
  width: max-content;
  animation: partners-scroll 32s linear infinite;
}
.partners:hover .partners__track { animation-play-state: paused; }
.partner {
  flex: none; display: flex; align-items: center; justify-content: center;
}
.partner img {
  max-height: 58px; width: auto; max-width: 220px; object-fit: contain;
  filter: grayscale(1); opacity: .68;
  transition: filter .25s, opacity .25s, transform .35s cubic-bezier(.16,1,.3,1);
}
.partner:hover img { filter: grayscale(0); opacity: 1; transform: scale(1.06); }

@keyframes partners-scroll {
  from { transform: translateX(0); }
  to   { transform: translateX(-50%); }
}
@media (prefers-reduced-motion: reduce) {
  .partners__track { animation: none; flex-wrap: wrap; width: auto; justify-content: center; }
  .partners { mask-image: none; -webkit-mask-image: none; }
}

/* callout / join box */
.callout {
  background: var(--ink); color: var(--paper);
  padding: clamp(36px, 6vw, 64px); border: 1px solid var(--ink);
}
.callout .eyebrow { color: #d98b90; }
.callout .eyebrow::before { background:#d98b90; }
.callout h2 { color: var(--paper); font-size: clamp(24px, 3.2vw, 38px); max-width: 26ch; }
.callout p { color: #cbc7bf; max-width: 56ch; }
.callout .mail { font-weight: 700; color: #fff; border-bottom: 1px solid rgba(255,255,255,.4); }
.callout .mail:hover { border-color: #fff; }

/* join form (inside dark .callout) */
.joinform { margin-top: 28px; max-width: 560px; }
.joinform__row { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
.joinform__field { display: flex; flex-direction: column; gap: 6px; margin-bottom: 14px; }
.joinform__field label {
  font-size: 11.5px; font-weight: 700; letter-spacing: .12em;
  text-transform: uppercase; color: #b6b2aa;
}
.joinform__field input, .joinform__field textarea {
  font: inherit; font-size: 15.5px; color: #fff;
  background: rgba(255,255,255,.07);
  border: 1px solid rgba(255,255,255,.22); border-radius: 2px;
  padding: 11px 13px; transition: border-color .18s, background .18s;
}
.joinform__field input:focus, .joinform__field textarea:focus {
  outline: none; border-color: #d98b90; background: rgba(255,255,255,.11);
}
.joinform__field textarea { resize: vertical; }
.joinform__submit { border: 0; cursor: pointer; }
.joinform__submit[disabled] { opacity: .6; cursor: default; }
.joinform__status { margin: 12px 0 0; font-size: 14.5px; min-height: 1.2em; }
.joinform__status.is-ok { color: #9fd8a4; }
.joinform__status.is-err { color: #e8a0a5; }
.joinform__alt { margin: 16px 0 0; font-size: 13.5px; color: #98948c; }
.joinform__alt a { color: #cbc7bf; border-bottom: 1px solid rgba(255,255,255,.25); }
.joinform__alt a:hover { color: #fff; }
@media (max-width: 560px) { .joinform__row { grid-template-columns: 1fr; } }

/* prose */
.prose p { max-width: 68ch; color: var(--ink-soft); }
.prose h3 { font-size: 22px; margin: 40px 0 14px; }
.prose ul { max-width: 68ch; color: var(--ink-soft); padding-left: 0; list-style: none; }
.prose ul li { position: relative; padding-left: 26px; margin-bottom: 12px; }
.prose ul li::before { content: "→"; position: absolute; left: 0; color: var(--accent); font-weight: 700; }

/* ---------------------------------------------------------------- footer */
.footer { border-top: 1px solid var(--line); background: var(--paper-2); }
.footer__grid { display: grid; grid-template-columns: 1.5fr 1fr 1fr; gap: 40px; padding-block: clamp(48px, 6vw, 72px); }
.footer h4 { font-size: 12px; letter-spacing: .16em; text-transform: uppercase; color: var(--muted); margin-bottom: 16px; }
.footer a { color: var(--ink-soft); font-size: 15px; display: block; padding: 5px 0; }
.footer a:hover { color: var(--accent); }
.footer__brand { display:flex; align-items:center; gap:12px; margin-bottom:16px; }
.footer__brand svg { width: 30px; height: 30px; }
.footer__desc { color: var(--muted); font-size: 14.5px; max-width: 38ch; }
.footer__bottom { border-top: 1px solid var(--line); padding: 22px 0; display: flex; flex-wrap: wrap; gap: 12px; justify-content: space-between; font-size: 13px; color: var(--muted); }
.social { display: flex; gap: 8px; }
.social a { border: 1px solid var(--line); width: 34px; height: 34px; display: flex; align-items: center; justify-content: center; border-radius: 2px; }
.social a:hover { background: var(--ink); color: var(--paper); border-color: var(--ink); }
.social svg { width: 16px; height: 16px; }

/* ---------------------------------------------------- scroll animations */
/* JS adds .reveal to content blocks, then .in when they scroll into view.
   Guarded so users who prefer reduced motion (and no-JS) see everything.  */
@media (prefers-reduced-motion: no-preference) {
  .reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: opacity .95s cubic-bezier(.16, 1, .3, 1),
                transform .95s cubic-bezier(.16, 1, .3, 1);
  }
  .reveal.in { opacity: 1; transform: none; }

  /* gentle lift on interactive cards */
  a.cell { transition: transform .35s cubic-bezier(.16,1,.3,1), background .2s; }
  a.cell:hover { transform: translateY(-3px); background: var(--paper); }

  .btn { transition: background .18s, color .18s, transform .12s cubic-bezier(.16,1,.3,1); }
  .nav__caret { transition: transform .25s cubic-bezier(.16,1,.3,1); }
}

/* utility */
.mt-0 { margin-top: 0; }
.center { text-align: center; }
[hidden] { display: none !important; }
.muted { color: var(--muted); }

/* --------------------------------------------------------- responsive */
@media (max-width: 900px) {
  .grid--3 { grid-template-columns: 1fr 1fr; }
  .split { grid-template-columns: 1fr; }
  .split__aside { position: static; }
  .footer__grid { grid-template-columns: 1fr 1fr; }
  .stats { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 680px) {
  body { font-size: 16px; }
  .nav__links { display: none; }
  .nav__links.open {
    display: flex; flex-direction: column; align-items: stretch;
    position: absolute; top: var(--nav-h); left: 0; right: 0;
    background: var(--paper); border-bottom: 1px solid var(--line);
    padding: 10px var(--gutter) 20px; gap: 0; margin: 0;
    max-height: calc(100vh - var(--nav-h)); overflow-y: auto;
  }
  .nav__links.open .nav__link,
  .nav__links.open .nav__top { padding: 14px 4px; border-bottom: 1px solid var(--line-soft); width: 100%; justify-content: space-between; }
  .nav__links.open .nav__item { border-bottom: 1px solid var(--line-soft); }
  .nav__links.open .nav__item .nav__top { border-bottom: 0; }
  /* accordion sub-menu on mobile: flows inline, no absolute positioning */
  .nav__links.open .nav__menu {
    position: static; opacity: 1; visibility: visible; transform: none;
    box-shadow: none; border: 0; min-width: 0; padding: 0 0 8px 10px;
    display: none;
  }
  .nav__links.open .nav__item.open .nav__menu { display: block; }
  .nav__links.open .nav__sublink { padding: 10px 8px; }
  .nav__links.open .langtoggle { margin: 14px 0 0; align-self: flex-start; }
  .nav__toggle { display: block; }
  .grid--2, .grid--3 { grid-template-columns: 1fr; }
  .news__item { grid-template-columns: 1fr; gap: 4px; }
  .event { grid-template-columns: 1fr; }
  .footer__grid { grid-template-columns: 1fr; }
  .stats { grid-template-columns: 1fr 1fr; }
}