/* ============================================================
   haowei-jack-hua.com — academic portfolio
   Design: Apple-minimal · light gray canvas, SF system type,
   single blue accent, hairline borders, glass header.
   Governed by Kasidia Frontend Law (KFL).
   ============================================================ */

/* ---------- design tokens (KFL: color roles + shared contract) ---------- */
:root{
  /* color roles */
  --bg:#f5f5f7;            /* background base (low saturation) */
  --surface:#ffffff;       /* card surface */
  --surface-2:#fafafa;
  --text:#1d1d1f;          /* primary text */
  --text-body:#3a3a3c;     /* body copy */
  --text-2:#6e6e73;        /* secondary text */
  --text-3:#707077;        /* tertiary text (AA ≥4.5 on bg and surface) */
  --accent:#0071e3;        /* accent / theme (Apple blue) */
  --accent-strong:#0066cc;
  --accent-soft:rgba(0,113,227,.08);
  --accent-line:rgba(0,113,227,.22);
  --line:rgba(0,0,0,.08);       /* hairline */
  --line-strong:rgba(0,0,0,.16);
  --chip-bg:#f2f2f7;       /* neutral chip / icon chip */
  /* semantic state colors — bounded pill use only */
  --ok-bg:#e7f5ec; --ok:#1e7d43;
  --warn-bg:#fdf3e2; --warn:#b25000;
  --info-bg:#e8f1fd; --info:#0a66c2;
  --gray-bg:#f2f2f7; --gray:#6e6e73;
  /* geometry */
  --radius-lg:18px;
  --radius-md:14px;
  --radius-sm:10px;
  --shadow:0 1px 2px rgba(0,0,0,.03),0 10px 28px -12px rgba(0,0,0,.07);
  --shadow-hover:0 2px 4px rgba(0,0,0,.04),0 18px 44px -14px rgba(0,0,0,.14);
  /* typography */
  --font:-apple-system,BlinkMacSystemFont,"SF Pro Display","SF Pro Text","Helvetica Neue","Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --mono:ui-monospace,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;
  --ease:cubic-bezier(.25,.1,.25,1);
}

/* ---------- base / reset ---------- */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:72px}
body{
  font-family:var(--font);
  background:var(--bg);
  color:var(--text);
  line-height:1.65;
  font-size:16px;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
img,svg{display:block;max-width:100%}
a{color:var(--accent);text-decoration:none}
a:focus-visible,button:focus-visible{
  outline:2px solid var(--accent);outline-offset:2px;border-radius:6px;
}
.wrap{max-width:1100px;margin:0 auto;padding:0 24px}
.skip{position:absolute;left:-9999px;top:0}
.skip:focus{left:0;background:var(--surface);padding:10px 16px;z-index:100;color:var(--accent)}

/* ---------- shared card contract (KFL Law 2) ---------- */
/* one surface language for every card family; variants only in content layout */
.icard,.pcard,.tcard,.factcard{
  background:var(--surface);
  border:1px solid var(--line);
  border-radius:var(--radius-lg);
  box-shadow:var(--shadow);
  transition:transform .3s var(--ease),box-shadow .3s var(--ease),border-color .3s var(--ease);
}
.icard:hover,.pcard:hover,.tcard:hover{
  transform:translateY(-2px);
  box-shadow:var(--shadow-hover);
  border-color:var(--line-strong);
}
/* row family — publications / outputs share the same surface language */
.pub,.ocard{
  background:var(--surface);
  border:1px solid var(--line);
  border-radius:var(--radius-md);
  box-shadow:var(--shadow);
  transition:border-color .3s var(--ease),box-shadow .3s var(--ease);
}
.pub:hover,.ocard:hover{border-color:var(--line-strong);box-shadow:var(--shadow-hover)}
/* pill family — badges / status / tags share one geometry */
.badge,.status,.tag,.ph{
  display:inline-block;
  border-radius:999px;
  font-size:11px;
  font-weight:600;
  letter-spacing:.02em;
  padding:4px 11px;
  line-height:1.3;
}

/* ---------- header (frosted glass) ---------- */
.site-head{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.72);
  backdrop-filter:saturate(180%) blur(20px);
  -webkit-backdrop-filter:saturate(180%) blur(20px);
  border-bottom:1px solid var(--line);
}
.head-inner{display:flex;align-items:center;justify-content:space-between;height:56px}
.brand{display:flex;align-items:center;gap:10px;color:var(--text)}
.brand .mono{
  width:32px;height:32px;border-radius:8px;flex:none;
  background:var(--text);
  color:#fff;font-weight:700;font-size:13px;
  display:flex;align-items:center;justify-content:center;
}
.brand small{display:block;font-weight:500;font-size:10px;color:var(--text-3);letter-spacing:.1em;text-transform:uppercase;line-height:1.25}
.brand b{font-size:14.5px;font-weight:600;line-height:1.25;letter-spacing:-.01em}
.nav{display:flex;align-items:center;gap:2px}
.nav a{
  padding:7px 13px;border-radius:999px;font-size:14px;color:var(--text-2);font-weight:500;
  transition:color .2s var(--ease),background-color .2s var(--ease);
}
.nav a:hover{background:var(--chip-bg);color:var(--text)}
.nav a.here{color:var(--text);background:rgba(0,0,0,.06)}
.nav .cta{
  margin-left:8px;background:var(--accent);color:#fff !important;border-radius:999px;
  padding:7px 17px;font-weight:600;
}
.nav .cta:hover{background:var(--accent-strong);color:#fff !important}
.nav-toggle{
  display:none;background:none;border:1px solid var(--line-strong);border-radius:var(--radius-sm);
  width:44px;height:44px;cursor:pointer;align-items:center;justify-content:center;
}
.nav-toggle svg{width:20px;height:20px;stroke:var(--text)}

/* ---------- hero / page band (light, type-led) ---------- */
.hero{
  padding:96px 0 32px;
  background:
    radial-gradient(900px 480px at 82% -18%, rgba(0,113,227,.09), transparent 60%),
    radial-gradient(700px 420px at -8% 118%, rgba(0,113,227,.05), transparent 55%),
    var(--bg);
  color:var(--text);
}
.hero .kicker{font-family:var(--mono);font-size:12.5px;letter-spacing:.18em;text-transform:uppercase;color:var(--accent);margin-bottom:20px}
.hero h1{font-size:clamp(36px,6.4vw,68px);line-height:1.04;font-weight:700;color:var(--text);letter-spacing:-.025em}
.hero h1 .zh{display:block;font-size:.3em;font-weight:400;color:var(--text-2);letter-spacing:.22em;margin-top:16px}
.hero .role{font-size:clamp(16.5px,2vw,19px);color:var(--text-2);max-width:780px;margin-top:24px;line-height:1.7}
.hero .role b{color:var(--text)}
.hero .meta{
  display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;
  margin-top:30px;max-width:560px;
}
.hero .meta a{
  display:inline-flex;align-items:center;gap:7px;justify-content:flex-start;
  border:1px solid var(--line-strong);background:var(--surface);color:var(--text-2);
  border-radius:999px;padding:8px 14px;font-size:13px;font-weight:500;
  transition:border-color .2s var(--ease),color .2s var(--ease),background-color .2s var(--ease);
}
.hero .meta a:hover{border-color:var(--accent);color:var(--accent);background:var(--accent-soft)}
.hero .meta svg{width:15px;height:15px;stroke:currentColor;fill:none}
/* hero portrait — right column, large-radius card (Apple pattern) */
.hero-grid{display:grid;grid-template-columns:1fr 380px;gap:56px;align-items:center}
.hero-copy{min-width:0}
.portrait{margin:0}
.portrait img{
  width:100%;height:auto;display:block;
  border-radius:24px;border:1px solid rgba(0,0,0,.07);
  box-shadow:0 1px 2px rgba(0,0,0,.05),0 12px 32px rgba(0,0,0,.1),0 28px 56px -20px rgba(0,0,0,.2);
}
.stats{
  display:grid;grid-template-columns:repeat(4,1fr);gap:1px;
  background:var(--line);border:1px solid var(--line);
  border-radius:var(--radius-lg);overflow:hidden;margin-top:52px;
}
.stats div{background:var(--surface);padding:24px 22px}
.stats b{display:block;height:32px;font-size:27px;font-weight:700;color:var(--text);line-height:1.2;letter-spacing:-.02em}
.stats b.txt{font-size:20px;font-weight:600;letter-spacing:-.01em;padding-top:8px}
.stats span{font-size:11.5px;color:var(--text-3);letter-spacing:.07em;text-transform:uppercase}

.pageband{
  padding:72px 0 52px;
  background:
    radial-gradient(760px 380px at 88% -30%, rgba(0,113,227,.08), transparent 60%),
    var(--bg);
  color:var(--text);
}
.pageband .zh{font-family:var(--mono);font-size:12px;letter-spacing:.22em;color:var(--accent);text-transform:uppercase;margin-bottom:14px}
.pageband h1{font-size:clamp(32px,4.6vw,44px);font-weight:700;color:var(--text);letter-spacing:-.022em}
.pageband p{color:var(--text-2);max-width:720px;margin-top:14px;font-size:15.5px}

/* ---------- sections ---------- */
section{padding:76px 0}
section.alt{background:var(--surface)}
.sec-head{display:flex;align-items:center;gap:14px;margin-bottom:28px}
.sec-head .no{font-family:var(--mono);font-size:12.5px;color:var(--accent);font-weight:700}
.sec-head h2{font-size:clamp(26px,3.2vw,34px);font-weight:700;color:var(--text);letter-spacing:-.02em}
.sec-head .en{font-size:12px;color:var(--text-3);letter-spacing:.08em;text-transform:uppercase}
.sec-sub{color:var(--text-2);max-width:780px;margin:-16px 0 30px;font-size:15.5px}

/* about */
.about-grid{display:grid;grid-template-columns:1fr 320px;gap:40px;align-items:start}
.about p{color:var(--text-body);margin-bottom:16px;font-size:16px}
.about p strong{color:var(--text)}
.factcard{padding:26px}
.factcard h3{font-size:15px;font-weight:600;color:var(--text);margin-bottom:14px;padding-bottom:12px;border-bottom:1px solid var(--line)}
.factcard ul{list-style:none}
.factcard li{display:flex;gap:11px;padding:8px 0;font-size:13.5px;color:var(--text-body);align-items:flex-start}
.factcard li::before{content:"";width:6px;height:6px;border-radius:50%;background:var(--accent);flex:none;margin-top:7px}

/* interest / contact / leadership cards */
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));gap:16px}
.grid.two{grid-template-columns:repeat(2,1fr)}
.icard{padding:26px;display:flex;flex-direction:column}
.icard .ico{
  width:40px;height:40px;border-radius:var(--radius-sm);background:var(--chip-bg);
  display:flex;align-items:center;justify-content:center;margin-bottom:16px;
}
.icard .ico svg{width:21px;height:21px;stroke:var(--text);fill:none;stroke-width:1.8}
.icard h3{font-size:17px;font-weight:600;color:var(--text);margin-bottom:4px;letter-spacing:-.01em}
.icard .cn{font-size:11.5px;color:var(--text-3);letter-spacing:.1em;margin-bottom:10px;display:block}
.icard p{font-size:14px;color:var(--text-body);line-height:1.6}
.icard .tags{display:flex;flex-wrap:wrap;gap:6px;margin-top:auto;padding-top:16px}
.tag{background:var(--gray-bg);color:var(--gray)}
a.tag{color:var(--text-2);transition:color .2s var(--ease),background-color .2s var(--ease)}
a.tag:hover{color:var(--accent);background:var(--accent-soft)}

/* timeline */
.timeline{position:relative;margin:8px 0 8px 8px;padding-left:36px}
.timeline::before{content:"";position:absolute;left:6px;top:10px;bottom:10px;width:2px;background:linear-gradient(180deg,var(--accent),var(--line))}
.tl-item{position:relative;padding-bottom:38px}
.tl-item:last-child{padding-bottom:0}
.tl-item::before{
  content:"";position:absolute;left:-36px;top:6px;width:12px;height:12px;border-radius:50%;
  background:var(--surface);border:3px solid var(--accent);
}
.tl-item .when{font-family:var(--mono);font-size:12px;color:var(--accent);font-weight:700;letter-spacing:.08em}
.tl-item h3{font-size:18px;font-weight:600;color:var(--text);margin:4px 0 6px;letter-spacing:-.01em}
.tl-item h3 .cn{font-size:12.5px;color:var(--text-3);font-weight:400;letter-spacing:.08em;margin-left:10px}
.tl-item p{font-size:14.5px;color:var(--text-body);max-width:840px;line-height:1.65}
.tl-item .where{font-size:13px;color:var(--text-3);margin-top:5px}
.tl-item .links{margin-top:10px;display:flex;flex-wrap:wrap;gap:18px}

/* shared underline-link contract — blue + arrow; underline as hover feedback */
.links a,.pub .ext a{
  font-size:13px;font-weight:600;color:var(--accent);
  transition:color .2s var(--ease);
  display:inline-flex;align-items:center;gap:3px;
}
.links a:hover,.pub .ext a:hover{color:var(--accent-strong);text-decoration:underline;text-underline-offset:3px;text-decoration-color:var(--accent)}
.links svg,.pub .ext svg,.callout a svg{width:12px;height:12px;stroke:currentColor;fill:none;stroke-width:1.8}

/* project cards */
.pcard{padding:28px}
.pcard .top{display:flex;align-items:baseline;justify-content:space-between;gap:12px;flex-wrap:wrap}
.pcard h3{font-size:19px;font-weight:600;color:var(--text);letter-spacing:-.015em}
.pcard .status{font-size:11px}
.pcard .status.done{background:var(--ok-bg);color:var(--ok)}
.pcard .status.wip{background:var(--warn-bg);color:var(--warn)}
.pcard .status.pre{background:var(--info-bg);color:var(--info)}
.pcard .status.list{background:var(--gray-bg);color:var(--gray)}
.pcard .cn{font-size:11.5px;color:var(--text-3);letter-spacing:.1em;display:block;margin-bottom:12px}
.pcard p{font-size:14.5px;color:var(--text-body);margin-bottom:14px;line-height:1.65}
.pcard .meta{font-size:13px;color:var(--text-3);display:flex;flex-wrap:wrap;gap:6px 18px;margin-bottom:14px}
.pcard .meta b{color:var(--text);font-weight:600}
.pcard .tags{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:16px}
.pcard .links{display:flex;flex-wrap:wrap;gap:18px;font-size:13.5px}
.pcard .links .doi{font-family:var(--mono);font-size:12px;color:var(--text-3);font-weight:500}

/* publications */
.pub-year{font-size:20px;font-weight:700;color:var(--text);margin:38px 0 16px;display:flex;align-items:center;gap:16px;letter-spacing:-.01em}
.pub-year::after{content:"";flex:1;height:1px;background:var(--line)}
.pub{padding:20px 24px;margin-bottom:12px}
.pub .t{font-size:16px;font-weight:600;color:var(--text);line-height:1.5;display:block;letter-spacing:-.01em}
.pub .au{font-size:13.5px;color:var(--text-body);margin-top:7px}
.pub .au .me{font-weight:700;color:var(--text)}
.pub .ve{margin-top:10px;display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.badge{font-size:10.5px;font-weight:700;letter-spacing:.07em;text-transform:uppercase}
.badge.journal{background:var(--info-bg);color:var(--info)}
.badge.conf{background:var(--warn-bg);color:var(--warn)}
.badge.preprint{background:var(--gray-bg);color:var(--gray)}
.badge.other{background:var(--gray-bg);color:var(--gray)}
.pub .ext{margin-top:10px;display:flex;flex-wrap:wrap;gap:18px}
.pub .ext .doi{font-family:var(--mono);font-size:12px;color:var(--text-3);font-weight:500}
.note{
  font-size:13.5px;color:var(--text-2);
  border-left:3px solid var(--accent);
  padding:10px 16px;background:var(--surface-2);
  border-radius:0 var(--radius-sm) var(--radius-sm) 0;margin-top:24px;
}
.note a{font-weight:600}

/* outputs */
.ocard{border-style:dashed;border-color:var(--line-strong);padding:20px 24px;margin-bottom:12px}
.ocard h4{font-size:15.5px;font-weight:600;color:var(--text);margin-bottom:5px}
.ocard p{font-size:13.5px;color:var(--text-2)}
.ocard .ph{
  background:var(--gray-bg);color:var(--gray);margin-left:8px;vertical-align:middle;
  text-transform:uppercase;font-size:10px;font-weight:700;letter-spacing:.08em;
}

/* team */
.tcard{padding:24px;display:flex;flex-direction:column}
.tcard .ava{
  width:56px;height:56px;border-radius:50%;
  background:var(--chip-bg);color:var(--text);
  font-weight:600;font-size:17px;
  display:flex;align-items:center;justify-content:center;margin-bottom:16px;flex:none;
}
.tcard h3{margin-top:auto;font-size:17px;font-weight:600;color:var(--text);letter-spacing:-.01em}
.tcard .role{font-size:12px;color:var(--accent);font-weight:600;margin:3px 0 9px;letter-spacing:.02em}
.tcard p{font-size:13.5px;color:var(--text-body);line-height:1.6}
.tcard .inst{font-size:12px;color:var(--text-3);margin-top:10px;line-height:1.5}
.tcard.ph{background:transparent;border-style:dashed;box-shadow:none}
.tcard.ph:hover{transform:none;box-shadow:none}
.tcard.ph h3{color:var(--text-3)}
.tcard.ph .ava{background:transparent;color:var(--text-3);border:2px dashed var(--line-strong)}
.tcard.ph .ava svg{width:22px;height:22px;stroke:var(--text-3)}

/* callout */
.callout{
  background:var(--accent-soft);border:1px solid var(--accent-line);
  border-radius:var(--radius-md);padding:18px 22px;margin-top:30px;
  font-size:14px;color:var(--info);
}
.callout b{color:#0a4d8f}
.callout a{font-weight:600}

/* footer */
.site-foot{border-top:1px solid var(--line);padding:52px 0 36px;margin-top:24px}
.foot-grid{display:flex;justify-content:space-between;gap:32px;flex-wrap:wrap}
.foot-col h4{font-size:14px;font-weight:600;color:var(--text);margin-bottom:14px}
.foot-col a,.foot-col span{display:block;font-size:13px;color:var(--text-2);padding:3.5px 0;transition:color .2s var(--ease)}
.foot-col a:hover{color:var(--accent)}
.foot-bottom{
  margin-top:34px;padding-top:18px;border-top:1px solid var(--line);
  display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;
  font-size:12px;color:var(--text-3);
}

/* ---------- motion (KFL Law 3) ---------- */
/* enter: rise+fade in place; reduced motion: no spatial travel */
.rv{opacity:0;transform:translateY(14px);transition:opacity .6s var(--ease),transform .6s var(--ease)}
.rv.on{opacity:1;transform:none}
/* mobile nav: enter path = fade + drop 10px; close reverses the same path */
@media (prefers-reduced-motion:reduce){
  .rv{opacity:1;transform:none;transition:none}
  html{scroll-behavior:auto}
  .icard,.pcard,.tcard{transition:none}
  .nav{transition:none}
}

/* ---------- responsive (alignment preserved per viewport) ---------- */
@media (max-width:900px){
  .about-grid{grid-template-columns:1fr;gap:28px}
  .hero-grid{grid-template-columns:1fr;gap:36px}
  .portrait{max-width:320px}
}
@media (max-width:720px){
  .stats{grid-template-columns:repeat(2,1fr)}
  .grid.two{grid-template-columns:1fr}
  .nav{
    position:fixed;inset:56px 0 auto 0;background:rgba(255,255,255,.97);
    backdrop-filter:saturate(180%) blur(20px);
    -webkit-backdrop-filter:saturate(180%) blur(20px);
    flex-direction:column;align-items:stretch;
    padding:10px 20px 18px;border-bottom:1px solid var(--line);
    transform:translateY(-10px);opacity:0;pointer-events:none;
    transition:transform .3s var(--ease),opacity .3s var(--ease);
    box-shadow:0 24px 48px -24px rgba(0,0,0,.18);
  }
  .nav.open{transform:none;opacity:1;pointer-events:auto}
  .nav a{padding:13px 14px;border-radius:var(--radius-sm);font-size:15px}
  .nav .cta{margin:10px 0 0;text-align:center}
  .nav-toggle{display:flex}
  .hero{padding:64px 0 44px}
  .hero .meta{grid-template-columns:1fr;max-width:none}
  section{padding:60px 0}
  .tl-item .when{font-size:11px}
  .wrap{padding:0 20px}
}