/* ============================================================
   OSICF — Open Source Innovation & Cooperation Forum
   Design language inherited from woss.org.cn (forest/mist palette)
   ============================================================ */
:root{
  --mist-50:#eef6f0; --mist-100:#dcefe1; --mist-200:#c3e3cc;
  --sage-300:#a4d0b0; --sage-400:#86bd95; --sage-500:#67a578;
  --forest-600:#4a8760; --forest-700:#336048; --forest-800:#1f4530;
  --forest-900:#132c1e; --ink-950:#0a1a11;
  --paper:#f7faf7; --white:#ffffff; --gold:#d9c896; --gold-deep:#c2ac72;
  --text-on-dark:#f3f8f4; --text-on-dark-muted:rgba(243,248,244,.72);
  --text-on-light:#16301f; --text-on-light-muted:rgba(22,48,31,.66);
  --font-head:'Poppins','Noto Sans SC',-apple-system,'PingFang SC','Microsoft YaHei',sans-serif;
  --font-serif:'Fraunces','Noto Serif SC',Georgia,serif;
  --ease:cubic-bezier(.4,0,.2,1);
  --dur:340ms;
  --container:1180px;
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--font-head);color:var(--text-on-light);background:var(--paper);
  -webkit-font-smoothing:antialiased;overflow-x:hidden;line-height:1.6}
img{max-width:100%;display:block}
a{color:inherit;text-decoration:none}
ul{list-style:none}
h1,h2,h3{font-weight:700;line-height:1.15}
.wrap{max-width:var(--container);margin:0 auto;padding:0 32px}
.eyebrow{font-weight:600;font-size:.78rem;letter-spacing:.22em;text-transform:uppercase;color:var(--forest-600)}
.eyebrow.gold{color:var(--gold)}
.section{padding:110px 0}
.section-dark{background:linear-gradient(180deg,var(--forest-900),var(--ink-950));color:var(--text-on-dark)}
.section-mist{background:linear-gradient(180deg,var(--mist-50),var(--paper))}
.section-title{font-family:var(--font-serif);font-size:clamp(1.9rem,4vw,2.9rem);margin:14px 0 10px;letter-spacing:.01em}
.section-sub{color:var(--text-on-light-muted);max-width:640px;margin-bottom:52px}
.section-dark .section-sub{color:var(--text-on-dark-muted)}
.section-dark .section-title{color:var(--white)}
.lead{font-family:var(--font-serif);font-size:1.25rem;line-height:1.7;color:var(--forest-800)}

/* ---------- mist background ---------- */
.mist-bg{position:relative;background:
  linear-gradient(135deg,rgba(255,255,255,.10) 0,rgba(255,255,255,0) 24%),
  repeating-linear-gradient(100deg,rgba(255,255,255,.05) 0,rgba(255,255,255,.05) 140px,rgba(255,255,255,0) 140px,rgba(255,255,255,0) 280px),
  linear-gradient(200deg,var(--mist-100) 0,var(--sage-400) 38%,var(--forest-700) 70%,var(--ink-950) 100%);
  background-color:var(--forest-800);color:var(--text-on-dark)}

/* ---------- nav ---------- */
.site-nav{position:fixed;top:0;left:0;right:0;z-index:100;padding:20px 0;
  transition:background var(--dur) var(--ease),padding var(--dur) var(--ease),box-shadow var(--dur) var(--ease)}
.site-nav.nav-solid{padding:12px 0;background:rgba(19,44,30,.92);backdrop-filter:blur(10px);box-shadow:0 8px 24px rgba(0,0,0,.18)}
.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:20px}
.brand{display:flex;align-items:center;gap:12px;color:var(--white)}
.brand-mark-img{width:44px;height:44px;object-fit:contain;filter:drop-shadow(0 2px 6px rgba(0,0,0,.25))}
.brand-text{font-weight:600;font-size:1.05rem;letter-spacing:.06em}
.nav-links{display:flex;align-items:center;gap:30px}
.nav-links a{color:rgba(243,248,244,.85);font-size:.92rem;font-weight:500;transition:color .2s}
.nav-links a:hover{color:var(--gold)}
.nav-cta{padding:9px 20px;border:1.5px solid var(--gold);border-radius:999px;color:var(--gold)!important;transition:all .2s}
.nav-cta:hover{background:var(--gold);color:var(--forest-900)!important}
.nav-right{display:flex;align-items:center;gap:14px}
.lang-switch{display:flex;align-items:center;gap:6px;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.25);
  border-radius:999px;padding:6px 14px;color:var(--white);cursor:pointer;font-family:inherit;font-size:.85rem;font-weight:600;
  transition:background .2s}
.lang-switch:hover{background:rgba(255,255,255,.22)}
.lang-opt{opacity:.55;transition:opacity .2s}
.lang-opt.active{opacity:1;color:var(--gold)}
.lang-divider{opacity:.4}
.nav-toggle{display:none;flex-direction:column;gap:5px;background:none;border:0;cursor:pointer;padding:6px}
.nav-toggle span{width:22px;height:2px;background:var(--white);border-radius:2px;transition:all .3s}

/* ---------- hero ---------- */
.hero{min-height:100svh;display:flex;align-items:center;padding:140px 0 90px}
.hero-inner{max-width:860px}
.hero-eyebrow{color:var(--gold);margin-bottom:22px}
.hero-title{font-family:var(--font-serif);font-size:clamp(2.6rem,6.4vw,4.6rem);color:var(--white);
  line-height:1.12;letter-spacing:.01em;margin-bottom:18px}
.hero-motto{font-family:var(--font-serif);font-style:italic;font-size:clamp(1.05rem,2.2vw,1.4rem);
  color:var(--gold);margin-bottom:16px}
.hero-sub{color:var(--text-on-dark-muted);max-width:620px;font-size:1.02rem;margin-bottom:36px}
.hero-meta{display:flex;flex-wrap:wrap;gap:14px 34px;margin-bottom:42px}
.hero-meta-item{display:flex;align-items:center;gap:9px;color:rgba(243,248,244,.88);font-size:.94rem;font-weight:500}
.hero-meta-item svg{width:19px;height:19px;flex:none;stroke:var(--gold)}
.hero-actions{display:flex;flex-wrap:wrap;gap:16px}
.btn{display:inline-flex;align-items:center;justify-content:center;padding:14px 32px;border-radius:999px;
  font-weight:600;font-size:.95rem;letter-spacing:.02em;transition:all .25s var(--ease);cursor:pointer;border:0}
.btn-gold{background:linear-gradient(140deg,var(--gold),var(--gold-deep));color:var(--forest-900);box-shadow:0 10px 26px rgba(217,200,150,.32)}
.btn-gold:hover{transform:translateY(-2px);box-shadow:0 16px 34px rgba(217,200,150,.42)}
.btn-ghost{border:1.5px solid rgba(243,248,244,.5);color:var(--text-on-dark)}
.btn-ghost:hover{border-color:var(--gold);color:var(--gold)}
.btn-lg{padding:17px 44px;font-size:1.02rem}
.btn-disabled{cursor:default;opacity:.75}
.btn-disabled:hover{transform:none;box-shadow:0 10px 26px rgba(217,200,150,.32)}
.hero-scroll{position:absolute;left:50%;bottom:26px;transform:translateX(-50%);width:24px;height:38px;
  border:1.5px solid rgba(243,248,244,.45);border-radius:14px}
.hero-scroll span{position:absolute;left:50%;top:7px;width:3px;height:7px;margin-left:-1.5px;border-radius:3px;
  background:var(--gold);animation:scrollDot 1.8s infinite}
@keyframes scrollDot{0%{opacity:1;transform:translateY(0)}70%{opacity:0;transform:translateY(12px)}100%{opacity:0}}

/* ---------- stats ---------- */
.stats{background:var(--white);border-bottom:1px solid var(--mist-100);padding:44px 0}
.stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;text-align:center}
.stat-num{font-family:var(--font-serif);font-size:clamp(1.9rem,3.4vw,2.7rem);font-weight:700;color:var(--forest-700)}
.stat-label{font-size:.88rem;color:var(--text-on-light-muted);margin-top:4px}

/* ---------- about ---------- */
.about-cols{display:grid;grid-template-columns:5fr 7fr;gap:56px;margin-top:38px}
.about-body p{color:var(--text-on-light-muted);margin-bottom:16px}
.challenges{display:grid;grid-template-columns:repeat(4,1fr);gap:18px;margin-top:56px}
.challenge{background:var(--white);border:1px solid var(--mist-100);border-radius:16px;padding:26px 22px;
  transition:transform .3s var(--ease),box-shadow .3s var(--ease)}
.challenge:hover{transform:translateY(-4px);box-shadow:0 16px 36px rgba(19,44,30,.10)}
.challenge-icon{width:42px;height:42px;border-radius:11px;display:flex;align-items:center;justify-content:center;
  background:var(--mist-100);color:var(--forest-700);margin-bottom:16px}
.challenge-icon svg{width:21px;height:21px}
.challenge h3{font-size:1rem;margin-bottom:8px;color:var(--forest-800)}
.challenge p{font-size:.86rem;color:var(--text-on-light-muted);line-height:1.6}

/* ---------- agenda timeline ---------- */
.timeline{position:relative;margin-top:20px}
.timeline::before{content:"";position:absolute;left:118px;top:8px;bottom:8px;width:2px;
  background:linear-gradient(180deg,var(--sage-500),rgba(134,189,149,.15))}
.tl-item{position:relative;display:grid;grid-template-columns:96px 1fr;gap:56px;padding:26px 0}
.tl-dot{position:absolute;left:112px;top:38px;width:14px;height:14px;border-radius:50%;
  background:var(--gold);box-shadow:0 0 0 5px rgba(217,200,150,.18)}
.tl-time{font-weight:600;color:var(--sage-300);font-size:.92rem;padding-top:8px;font-variant-numeric:tabular-nums;white-space:nowrap}
.tl-card{background:rgba(255,255,255,.045);border:1px solid rgba(255,255,255,.10);border-radius:18px;padding:26px 30px;
  transition:border-color .25s,background .25s}
.tl-card:hover{border-color:rgba(217,200,150,.45);background:rgba(255,255,255,.07)}
.tl-tag{display:inline-block;font-size:.72rem;font-weight:600;letter-spacing:.14em;text-transform:uppercase;
  padding:5px 12px;border-radius:999px;margin-bottom:12px}
.tl-tag.panel{background:rgba(217,200,150,.16);color:var(--gold);border:1px solid rgba(217,200,150,.4)}
.tl-tag.ceremony{background:rgba(164,208,176,.16);color:var(--sage-300);border:1px solid rgba(164,208,176,.4)}
.tl-tag.break{background:rgba(255,255,255,.08);color:rgba(243,248,244,.6);border:1px solid rgba(255,255,255,.15)}
.tl-title{font-size:1.22rem;color:var(--white);margin-bottom:6px}
.tl-note{font-size:.92rem;color:var(--text-on-dark-muted);margin-bottom:14px}
.tl-mod{font-size:.86rem;color:var(--sage-300);margin-bottom:12px}
.tl-mod strong{color:var(--gold);font-weight:600}
.tl-people{display:flex;flex-wrap:wrap;gap:10px}
.person-chip{display:flex;flex-direction:column;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.12);
  border-radius:12px;padding:10px 14px;min-width:190px;flex:1 1 210px}
.person-name{font-weight:600;font-size:.92rem;color:var(--white)}
.person-role{font-size:.78rem;color:var(--text-on-dark-muted);margin-top:2px;line-height:1.45}

/* ---------- speakers ---------- */
.speaker-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(258px,1fr));gap:20px}
.speaker-card{background:var(--white);border:1px solid var(--mist-100);border-radius:18px;padding:26px 24px;
  transition:transform .3s var(--ease),box-shadow .3s var(--ease)}
.speaker-card:hover{transform:translateY(-4px);box-shadow:0 18px 40px rgba(19,44,30,.12)}
.speaker-avatar{width:52px;height:52px;border-radius:50%;display:flex;align-items:center;justify-content:center;
  background:linear-gradient(140deg,var(--forest-700),var(--forest-900));color:var(--gold);
  font-weight:700;font-size:1.05rem;margin-bottom:16px;font-family:var(--font-serif)}
.speaker-name{font-size:1.02rem;color:var(--forest-900);margin-bottom:4px}
.speaker-role{font-size:.84rem;color:var(--text-on-light-muted);line-height:1.5;margin-bottom:12px}
.speaker-tag{display:inline-block;font-size:.72rem;font-weight:600;color:var(--forest-600);
  background:var(--mist-100);border-radius:999px;padding:4px 11px}

/* ---------- orgs ---------- */
.org-cols{display:grid;grid-template-columns:repeat(2,1fr);gap:22px;margin-top:44px}
.org-block{background:var(--white);border:1px solid var(--mist-100);border-radius:18px;padding:30px}
.org-block h3{font-size:.8rem;letter-spacing:.18em;text-transform:uppercase;color:var(--forest-600);margin-bottom:18px}
.org-item{display:flex;align-items:flex-start;gap:12px;padding:11px 0;border-bottom:1px dashed var(--mist-100);font-size:.95rem}
.org-item:last-child{border-bottom:0}
.org-item::before{content:"";width:7px;height:7px;border-radius:50%;background:var(--gold-deep);margin-top:8px;flex:none}
.org-item small{display:block;color:var(--text-on-light-muted);font-size:.8rem}

/* ---------- venue ---------- */
.venue-cols{display:grid;grid-template-columns:7fr 5fr;gap:60px;align-items:center}
.venue-desc{color:var(--text-on-light-muted);margin:14px 0 28px;max-width:560px}
.venue-facts li{display:flex;align-items:flex-start;gap:12px;padding:12px 0;border-bottom:1px solid var(--mist-100);font-size:.94rem}
.venue-facts li:last-child{border-bottom:0}
.venue-facts svg{width:19px;height:19px;flex:none;stroke:var(--forest-600);margin-top:2px}
.venue-facts strong{font-weight:600;color:var(--forest-800)}
.venue-card{background:var(--white);border:1px solid var(--mist-100);border-radius:22px;padding:40px 34px;text-align:center;
  box-shadow:0 20px 50px rgba(19,44,30,.10)}
.venue-card-map{width:74px;height:74px;border-radius:50%;margin:0 auto 20px;display:flex;align-items:center;justify-content:center;
  background:var(--mist-100);color:var(--forest-700)}
.venue-card-map svg{width:34px;height:34px}
.venue-card h3{font-size:1.15rem;color:var(--forest-900);margin-bottom:10px}
.venue-card p{font-size:.9rem;color:var(--text-on-light-muted)}

/* ---------- register ---------- */
.register{text-align:center}
.register .section-title{color:var(--white)}
.register-sub{color:var(--text-on-dark-muted);max-width:600px;margin:16px auto 36px}
.register-note{margin-top:22px;font-size:.85rem;color:rgba(243,248,244,.6)}

/* ---------- footer ---------- */
.site-footer{background:var(--ink-950);color:var(--text-on-dark);padding:70px 0 0}
.footer-inner{display:grid;grid-template-columns:2fr 1fr 1fr;gap:44px;padding-bottom:52px}
.footer-mark{margin-bottom:16px}
.footer-desc{color:var(--text-on-dark-muted);font-size:.9rem;max-width:380px}
.footer-links{display:flex;flex-direction:column;gap:10px}
.footer-links a{color:var(--text-on-dark-muted);font-size:.9rem;transition:color .2s}
.footer-links a:hover{color:var(--gold)}
.footer-contact p{font-size:.8rem;letter-spacing:.16em;text-transform:uppercase;color:var(--sage-400);margin-bottom:10px}
.footer-contact a{color:var(--gold);font-size:.95rem}
.footer-bottom{border-top:1px solid rgba(243,248,244,.12);padding:22px 0}
.footer-bottom p{font-size:.82rem;color:rgba(243,248,244,.5)}

/* ---------- reveal animation ---------- */
.reveal{opacity:0;transform:translateY(26px);transition:opacity .7s var(--ease),transform .7s var(--ease)}
.reveal.visible{opacity:1;transform:none}

/* ---------- responsive ---------- */
@media (max-width:960px){
  .stats-grid{grid-template-columns:repeat(2,1fr);gap:30px}
  .about-cols,.venue-cols{grid-template-columns:1fr;gap:36px}
  .challenges{grid-template-columns:repeat(2,1fr)}
  .org-cols{grid-template-columns:1fr}
  .footer-inner{grid-template-columns:1fr;gap:32px}
  .timeline::before{left:8px}
  .tl-dot{left:2px}
  .tl-item{grid-template-columns:1fr;gap:8px;padding-left:32px}
  .tl-time{padding-top:0}
  .nav-links{position:fixed;inset:0 0 0 auto;width:min(78vw,320px);background:rgba(10,26,17,.97);backdrop-filter:blur(12px);
    flex-direction:column;align-items:flex-start;justify-content:center;padding:40px;gap:26px;
    transform:translateX(100%);transition:transform .35s var(--ease)}
  .nav-links.open{transform:none}
  .nav-links a{font-size:1.1rem}
  .nav-toggle{display:flex;z-index:110}
  .nav-toggle.open span:nth-child(1){transform:translateY(7px) rotate(45deg)}
  .nav-toggle.open span:nth-child(2){opacity:0}
  .nav-toggle.open span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
  .section{padding:78px 0}
  .brand-text{display:none}
}
@media (max-width:560px){
  .challenges{grid-template-columns:1fr}
  .stats-grid{grid-template-columns:repeat(2,1fr)}
}