/* ============================================================
   itslingyu.com — Seren Liu
   ============================================================ */

/* ---------- tokens ---------- */
:root{
  --paper:#FBFAF7;
  --paper-2:#F3F1EB;
  --ink:#16181C;
  --ink-2:#3C4046;
  --muted:#6E7178;
  --line:#E3E0D8;
  --line-2:#D2CEC4;
  --accent:#C0491D;
  --accent-soft:#FBEFE9;
  --shadow:0 1px 2px rgba(20,22,26,.04), 0 8px 24px -12px rgba(20,22,26,.14);
  --shadow-lg:0 2px 4px rgba(20,22,26,.05), 0 24px 56px -24px rgba(20,22,26,.22);

  --sans:'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  --mono:'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;

  --wrap:1140px;
  --gut:clamp(20px, 5vw, 48px);
  --r:14px;
}

@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --paper:#0D0E10;
    --paper-2:#141619;
    --ink:#EDEBE6;
    --ink-2:#C3C1BC;
    --muted:#8D9097;
    --line:#22252A;
    --line-2:#2E3237;
    --accent:#F2793F;
    --accent-soft:#1E1512;
    --shadow:0 1px 2px rgba(0,0,0,.4), 0 8px 24px -12px rgba(0,0,0,.6);
    --shadow-lg:0 2px 4px rgba(0,0,0,.4), 0 24px 56px -24px rgba(0,0,0,.7);
  }
}
:root[data-theme="dark"]{
  --paper:#0D0E10;
  --paper-2:#141619;
  --ink:#EDEBE6;
  --ink-2:#C3C1BC;
  --muted:#8D9097;
  --line:#22252A;
  --line-2:#2E3237;
  --accent:#F2793F;
  --accent-soft:#1E1512;
  --shadow:0 1px 2px rgba(0,0,0,.4), 0 8px 24px -12px rgba(0,0,0,.6);
  --shadow-lg:0 2px 4px rgba(0,0,0,.4), 0 24px 56px -24px rgba(0,0,0,.7);
}

/* ---------- reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%; scroll-behavior:smooth; scroll-padding-top:90px}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:var(--sans);
  font-size:17px;
  line-height:1.62;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}
h1,h2,h3,h4{margin:0; font-weight:600; letter-spacing:-.022em; line-height:1.14}
p{margin:0}
ul,ol,dl,dd{margin:0; padding:0; list-style:none}
a{color:inherit; text-decoration:none}
em{font-style:italic}
img{max-width:100%; display:block}
button{font:inherit; color:inherit}
::selection{background:var(--accent); color:#fff}

.wrap{width:100%; max-width:var(--wrap); margin-inline:auto; padding-inline:var(--gut)}

.skip{position:absolute; left:-9999px; top:0; background:var(--ink); color:var(--paper); padding:10px 16px; z-index:100; border-radius:0 0 8px 0}
.skip:focus{left:0}
:focus-visible{outline:2px solid var(--accent); outline-offset:3px; border-radius:4px}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex; align-items:center; gap:8px;
  background:var(--ink); color:var(--paper);
  padding:13px 22px; border-radius:100px;
  font-size:15px; font-weight:500; letter-spacing:-.01em;
  border:1px solid var(--ink);
  transition:transform .18s cubic-bezier(.2,.8,.3,1), background .18s, box-shadow .18s;
  white-space:nowrap;
}
.btn:hover{transform:translateY(-1px); box-shadow:var(--shadow)}
.btn:active{transform:translateY(0)}
.btn--ghost{background:transparent; color:var(--ink); border-color:var(--line-2)}
.btn--ghost:hover{border-color:var(--ink)}
.btn--sm{padding:9px 17px; font-size:14px}

.iconbtn{
  display:grid; place-items:center; width:38px; height:38px;
  background:transparent; border:1px solid var(--line); border-radius:100px;
  cursor:pointer; transition:border-color .18s, color .18s;
}
.iconbtn:hover{border-color:var(--line-2); color:var(--accent)}

/* ---------- nav ---------- */
.nav{
  position:sticky; top:0; z-index:50;
  background:color-mix(in srgb, var(--paper) 82%, transparent);
  backdrop-filter:saturate(180%) blur(14px);
  -webkit-backdrop-filter:saturate(180%) blur(14px);
  border-bottom:1px solid transparent;
  transition:border-color .25s, background .25s;
}
.nav.is-stuck{border-bottom-color:var(--line)}
.nav__inner{display:flex; align-items:center; gap:28px; height:68px}
.mark{display:flex; align-items:center; gap:9px; margin-right:auto}
.mark__glyph{
  display:grid; place-items:center; width:30px; height:30px;
  background:var(--ink); color:var(--paper);
  border-radius:8px; font-size:16px; line-height:1;
  font-family:Georgia,'Songti SC','Noto Serif SC',serif;
  padding-bottom:1px;
}
.mark__text{font-weight:600; letter-spacing:-.02em; font-size:16px}
.nav__links{display:flex; gap:26px}
.nav__links a{
  font-size:14.5px; color:var(--muted); font-weight:450;
  position:relative; transition:color .18s;
}
.nav__links a::after{
  content:''; position:absolute; left:0; right:0; bottom:-5px; height:1.5px;
  background:var(--accent); transform:scaleX(0); transform-origin:left;
  transition:transform .22s cubic-bezier(.2,.8,.3,1);
}
.nav__links a:hover{color:var(--ink)}
.nav__links a:hover::after{transform:scaleX(1)}
.nav__actions{display:flex; align-items:center; gap:10px}
@media (max-width:820px){ .nav__links{display:none} }
@media (max-width:520px){ .nav__inner{gap:14px} .btn--sm{padding:8px 14px; font-size:13.5px} }

/* ---------- hero ---------- */
.hero{position:relative; padding:clamp(64px,11vw,132px) 0 clamp(56px,8vw,88px); overflow:hidden}
.hero__grid{
  position:absolute; inset:-1px 0 auto 0; height:120%;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size:68px 68px;
  opacity:.55;
  mask-image:radial-gradient(120% 78% at 22% 0%, #000 0%, transparent 68%);
  -webkit-mask-image:radial-gradient(120% 78% at 22% 0%, #000 0%, transparent 68%);
  pointer-events:none;
}
.hero__inner{position:relative}

.status{
  display:inline-flex; align-items:center; gap:9px;
  font-family:var(--mono); font-size:12.5px; letter-spacing:.01em;
  color:var(--ink-2);
  background:var(--paper-2); border:1px solid var(--line);
  padding:7px 15px 7px 12px; border-radius:100px;
  margin-bottom:34px;
}
.status__dot{
  width:7px; height:7px; border-radius:50%; background:#1FA463; flex:none;
  box-shadow:0 0 0 3px color-mix(in srgb, #1FA463 22%, transparent);
  animation:pulse 2.6s ease-in-out infinite;
}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.45}}

.hero__title{
  font-size:clamp(2.6rem, 7.2vw, 5.05rem);
  letter-spacing:-.038em;
  line-height:1.03;
  max-width:25ch;
  margin-bottom:30px;
}
.hero__title em{
  font-style:italic;
  color:var(--accent);
  font-family:Georgia,'Times New Roman',serif;
  letter-spacing:-.02em;
}
.hero__lede{
  max-width:62ch; font-size:clamp(1.02rem,1.9vw,1.2rem);
  color:var(--ink-2); line-height:1.68;
}
.hero__lede strong{color:var(--ink); font-weight:600}
.hero__cta{display:flex; flex-wrap:wrap; gap:12px; margin-top:36px}

.stats{
  display:grid; grid-template-columns:repeat(4,1fr);
  gap:1px; background:var(--line);
  border:1px solid var(--line); border-radius:var(--r);
  overflow:hidden; margin-top:clamp(48px,7vw,76px);
}
.stat{background:var(--paper); padding:24px 22px}
.stat dt{
  font-family:var(--mono); font-size:11.5px; letter-spacing:.05em;
  text-transform:uppercase; color:var(--muted); margin-bottom:9px;
}
.stat .num{
  font-size:clamp(1.9rem,3.4vw,2.5rem); font-weight:600;
  letter-spacing:-.035em; line-height:1;
  font-variant-numeric:tabular-nums;
}
.stat .unit{font-size:.5em; color:var(--accent); margin-left:2px; font-weight:500; letter-spacing:0}
@media (max-width:760px){
  .stats{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:400px){
  .stats{grid-template-columns:1fr}
}

/* ---------- sections ---------- */
.section{padding:clamp(72px,10vw,124px) 0; border-top:1px solid var(--line)}
.section--alt{background:var(--paper-2)}

.shead{max-width:62ch; margin-bottom:clamp(40px,6vw,64px)}
.shead__idx{
  display:block; font-family:var(--mono); font-size:12px;
  letter-spacing:.14em; color:var(--accent); margin-bottom:16px;
}
.shead h2{font-size:clamp(1.75rem,3.7vw,2.7rem); letter-spacing:-.032em; margin-bottom:16px}
.shead__sub{color:var(--muted); font-size:clamp(1rem,1.7vw,1.1rem); line-height:1.66}

/* ---------- capability cards ---------- */
.cards{display:grid; grid-template-columns:repeat(3,1fr); gap:20px}
@media (max-width:940px){ .cards{grid-template-columns:1fr; gap:16px} }

.card{
  position:relative;
  background:var(--paper); border:1px solid var(--line);
  border-radius:var(--r); padding:30px 28px 26px;
  display:flex; flex-direction:column;
  transition:border-color .22s, transform .22s cubic-bezier(.2,.8,.3,1), box-shadow .22s;
}
.card:hover{border-color:var(--line-2); transform:translateY(-3px); box-shadow:var(--shadow-lg)}
.card__idx{
  display:grid; place-items:center; width:30px; height:30px;
  border:1px solid var(--line-2); border-radius:8px;
  font-family:var(--mono); font-size:12.5px; color:var(--accent);
  margin-bottom:20px;
}
.card h3{font-size:1.22rem; letter-spacing:-.024em; margin-bottom:13px}
.card p{color:var(--ink-2); font-size:15.4px; line-height:1.66; margin-bottom:22px}
.tags{display:flex; flex-wrap:wrap; gap:7px; margin-top:auto}
.tags li{
  font-family:var(--mono); font-size:11.5px; color:var(--muted);
  background:var(--paper-2); border:1px solid var(--line);
  padding:4px 9px; border-radius:6px; line-height:1.5;
}
.section--alt .tags li{background:var(--paper)}

/* ---------- evidence ledger ---------- */
.ledger{border-top:1px solid var(--line-2)}
.row{
  display:grid; grid-template-columns:150px minmax(0,1fr) minmax(0,.82fr);
  gap:24px; align-items:baseline;
  padding:24px 4px; border-bottom:1px solid var(--line);
  transition:background .2s, padding-left .2s;
}
.row:hover{background:color-mix(in srgb, var(--accent) 4%, transparent); padding-left:14px}
.row__k{
  font-family:var(--mono); font-size:11.5px; letter-spacing:.06em;
  text-transform:uppercase; color:var(--accent);
}
.row__v{font-size:clamp(1.02rem,1.9vw,1.18rem); letter-spacing:-.018em; color:var(--ink)}
.row__v strong{font-weight:600; font-variant-numeric:tabular-nums}
.row__n{font-size:14.2px; color:var(--muted); line-height:1.55}
@media (max-width:800px){
  .row{grid-template-columns:1fr; gap:7px; padding:20px 4px}
  .row:hover{padding-left:4px}
}
.note{
  margin-top:28px; font-size:14.5px; color:var(--muted);
  padding-left:15px; border-left:2px solid var(--accent); line-height:1.6;
}

/* ---------- services ---------- */
.svcs{
  display:grid; grid-template-columns:repeat(2,1fr);
  gap:1px; background:var(--line);
  border:1px solid var(--line); border-radius:var(--r); overflow:hidden;
}
.svc{background:var(--paper); padding:30px 28px; transition:background .2s}
.svc:hover{background:var(--paper-2)}
.svc h3{font-size:1.1rem; letter-spacing:-.022em; margin-bottom:11px}
.svc p{color:var(--ink-2); font-size:15.2px; line-height:1.64}
@media (max-width:760px){ .svcs{grid-template-columns:1fr} }

.cta{
  margin-top:32px; padding:34px 34px;
  background:var(--ink); color:var(--paper);
  border-radius:var(--r);
  display:flex; align-items:center; justify-content:space-between; gap:28px; flex-wrap:wrap;
}
.cta h3{font-size:clamp(1.2rem,2.4vw,1.6rem); letter-spacing:-.028em; margin-bottom:9px}
.cta p{color:color-mix(in srgb, var(--paper) 66%, transparent); font-size:15.2px; max-width:56ch; line-height:1.62}
.cta .btn{background:var(--paper); color:var(--ink); border-color:var(--paper)}

/* ---------- about ---------- */
.about{display:grid; grid-template-columns:minmax(0,1.35fr) minmax(0,.85fr); gap:clamp(36px,6vw,72px)}
@media (max-width:900px){ .about{grid-template-columns:1fr} }
.about__body .shead{margin-bottom:28px}
.about__body p{color:var(--ink-2); font-size:clamp(1rem,1.8vw,1.1rem); line-height:1.72; margin-bottom:20px; max-width:60ch}
.about__body p:last-child{margin-bottom:0}

.about__side{display:flex; flex-direction:column; gap:26px}
.facts h3{
  font-family:var(--mono); font-size:11.5px; letter-spacing:.1em;
  text-transform:uppercase; color:var(--muted); font-weight:500;
  padding-bottom:11px; border-bottom:1px solid var(--line-2); margin-bottom:4px;
}
.facts li{
  display:flex; justify-content:space-between; align-items:baseline; gap:16px;
  padding:11px 0; border-bottom:1px solid var(--line);
}
.facts li span{font-size:15px; font-weight:500; white-space:nowrap}
.facts li em{font-style:normal; font-size:13px; color:var(--muted); text-align:right; line-height:1.45}

/* ---------- contact ---------- */
.contact{
  background:var(--ink); color:var(--paper);
  padding:clamp(80px,11vw,132px) 0;
  position:relative; overflow:hidden;
}
.contact__inner{text-align:center; position:relative}
.contact__eyebrow{font-family:var(--mono); font-size:12px; letter-spacing:.14em; color:var(--accent); margin-bottom:20px}
.contact__title{font-size:clamp(2.4rem,7vw,4.4rem); letter-spacing:-.04em; margin-bottom:18px}
.contact__lede{
  color:color-mix(in srgb, var(--paper) 62%, transparent);
  max-width:46ch; margin:0 auto; font-size:clamp(1rem,1.8vw,1.1rem); line-height:1.66;
}
.mailto{
  display:inline-block; margin-top:36px;
  font-size:clamp(1.05rem,3vw,1.7rem); font-weight:500; letter-spacing:-.028em;
  padding-bottom:6px; border-bottom:1.5px solid color-mix(in srgb, var(--paper) 32%, transparent);
  transition:border-color .2s, color .2s; word-break:break-word;
}
.mailto:hover{color:var(--accent); border-bottom-color:var(--accent)}
.social{display:flex; justify-content:center; flex-wrap:wrap; gap:26px; margin-top:44px}
.social a{
  font-family:var(--mono); font-size:12.5px; letter-spacing:.05em; text-transform:uppercase;
  color:color-mix(in srgb, var(--paper) 58%, transparent);
  transition:color .18s;
}
.social a:hover{color:var(--paper)}

/* ---------- footer ---------- */
.foot{background:var(--ink); color:color-mix(in srgb, var(--paper) 48%, transparent);
  border-top:1px solid color-mix(in srgb, var(--paper) 12%, transparent)}
.foot__inner{
  display:flex; justify-content:space-between; align-items:center; gap:16px;
  flex-wrap:wrap; padding-block:26px; font-size:13.5px;
}
.foot__dom{font-family:var(--mono); font-size:12.5px}

/* ---------- reveal ---------- */
.js .reveal{opacity:0; transform:translateY(16px)}
.reveal.in{opacity:1; transform:none; transition:opacity .62s cubic-bezier(.2,.8,.3,1), transform .62s cubic-bezier(.2,.8,.3,1)}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .js .reveal{opacity:1; transform:none}
  *,*::before,*::after{animation-duration:.01ms !important; transition-duration:.01ms !important}
}