/* =========================================================================
   Chen Dermatology — shared design system  (assets/css/site.css)
   System fonts only (no web-font downloads). This is the "non-critical"
   half of the hybrid critical-CSS pattern: it is loaded asynchronously
   after first paint. Critical above-the-fold rules are inlined per page.
   Single source of truth for every page — edit here, all pages update.
   ========================================================================= */
:root{
  --brand:#7c001f;--brand-dark:#5c0017;--brand-soft:#fbeef0;
  --ink:#241a1c;--slate:#6b5c60;--sand:#f8f5f2;--white:#fff;--line:#e9e2df;--gold:#c9a26b;
  --shadow:0 10px 40px rgba(124,0,31,.08);--shadow-lg:0 20px 60px rgba(124,0,31,.14);--radius:18px;
  --sans:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  --serif:Georgia,"Times New Roman",Times,serif;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{font-family:var(--sans);color:var(--ink);
  background:var(--white);line-height:1.7;-webkit-font-smoothing:antialiased;overflow-x:hidden}
h1,h2,h3,h4{font-family:var(--serif);font-weight:500;line-height:1.18;letter-spacing:-.01em}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
.wrap{max-width:1160px;margin:0 auto;padding:0 24px}
.narrow{max-width:880px}
.eyebrow{display:inline-block;font-family:var(--sans);font-weight:600;font-size:.72rem;
  letter-spacing:.18em;text-transform:uppercase;color:var(--brand);margin-bottom:14px}
.skip-link{position:absolute;left:-9999px;top:0;background:var(--brand);color:#fff;padding:12px 20px;z-index:999}
.skip-link:focus{left:0}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:9px;font-weight:600;font-size:.95rem;
  padding:14px 26px;border-radius:999px;transition:.25s;cursor:pointer;border:none;min-height:48px;font-family:inherit}
.btn-primary{background:var(--brand);color:#fff;box-shadow:0 8px 22px rgba(124,0,31,.28)}
.btn-primary:hover{background:var(--brand-dark);transform:translateY(-2px)}
.btn-ghost{background:transparent;color:var(--brand);border:1.5px solid var(--brand)}
.btn-ghost:hover{background:var(--brand-soft)}
.btn-wa{background:#25d366;color:#fff}
.btn-wa:hover{background:#1fb855;transform:translateY(-2px)}
header{position:sticky;top:0;z-index:100;background:rgba(255,255,255,.93);backdrop-filter:blur(12px);
  border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;height:74px}
.brand{display:flex;align-items:center;gap:12px;font-family:var(--serif);font-size:1.25rem;font-weight:600}
.brand-mark{width:42px;height:42px;flex-shrink:0;display:grid;place-items:center;overflow:hidden}
.brand-mark svg{width:100%;height:100%;display:block}
.brand small{display:block;font-family:var(--sans);font-size:.66rem;letter-spacing:.14em;
  text-transform:uppercase;color:var(--slate);font-weight:500}
.nav-links{display:flex;align-items:center;gap:30px;list-style:none}
.nav-links a{font-size:.92rem;font-weight:500;color:var(--slate);display:inline-flex;align-items:center;
  min-height:44px;padding:0 4px;transition:.2s}
.nav-links a:hover,.nav-links a.active{color:var(--brand)}
.nav-links a.active{font-weight:600}
.nav-cta{display:flex;align-items:center;gap:14px}
.lang{font-size:.85rem;color:var(--slate);font-weight:500;display:inline-flex;align-items:center;min-height:44px;gap:6px}
.lang b{color:var(--brand)}
.menu-btn{display:none;background:none;border:none;font-size:1.6rem;color:var(--ink);cursor:pointer;
  width:48px;height:48px;border-radius:10px}
main{display:block}
section{padding:76px 0}
.section-head{max-width:700px;margin-bottom:44px}
.section-head.center{margin-left:auto;margin-right:auto;text-align:center}
.section-head h2{font-size:clamp(1.6rem,3.2vw,2.3rem);margin-bottom:14px}
.section-head p{color:var(--slate);font-size:clamp(.98rem,2vw,1.05rem)}
.page-hero{background:linear-gradient(160deg,#fdf5f6 0%,var(--sand) 100%);padding:52px 0 58px;
  position:relative;overflow:hidden}
.page-hero::after{content:"";position:absolute;top:-140px;right:-100px;width:420px;height:420px;
  background:radial-gradient(circle,rgba(124,0,31,.10),transparent 70%);border-radius:50%}
.page-hero .wrap{position:relative;z-index:2}
.page-hero h1{font-size:clamp(1.9rem,4vw,2.9rem);margin-bottom:16px}
.page-hero p.lead{color:var(--slate);font-size:clamp(1rem,2vw,1.1rem);max-width:640px}
.page-hero .hero-actions{margin-top:26px}
.hero-actions{display:flex;gap:14px;flex-wrap:wrap}
.breadcrumb{display:flex;gap:8px;flex-wrap:wrap;font-size:.85rem;color:var(--slate);margin-bottom:16px;list-style:none}
.breadcrumb a{color:var(--brand);font-weight:500}
.breadcrumb li+li::before{content:"\203A";margin-right:8px;color:var(--line)}
/* Key-facts summary card (GEO friendly) */
.keyfacts{background:#fff;border:1px solid var(--line);border-left:4px solid var(--brand);
  border-radius:14px;padding:26px 28px;box-shadow:var(--shadow);margin-top:30px}
.keyfacts h2{font-size:1.1rem;margin-bottom:14px;font-family:var(--sans);font-weight:700;
  letter-spacing:.02em;text-transform:uppercase;font-size:.8rem;color:var(--brand)}
.keyfacts dl{display:grid;gap:12px}
.keyfacts .kf{display:flex;gap:14px;align-items:flex-start;font-size:.95rem}
.keyfacts dt{font-weight:700;min-width:132px;flex-shrink:0;color:var(--ink);font-size:.83rem;
  text-transform:uppercase;letter-spacing:.05em;padding-top:2px}
.keyfacts dd{color:var(--slate)}
.prose p{color:var(--slate);margin-bottom:16px}
.prose h3{font-size:1.3rem;margin:32px 0 12px}
.prose ul{list-style:none;margin-bottom:16px}
.prose ul li{position:relative;padding-left:24px;margin-bottom:9px;color:var(--slate)}
.prose ul li::before{content:"";position:absolute;left:0;top:10px;width:7px;height:7px;border-radius:50%;
  background:var(--brand);opacity:.5}
.prose a{color:var(--brand);font-weight:500;text-decoration:underline;text-underline-offset:3px}
.prose strong{color:var(--ink)}
.grid-2{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.grid-3{display:grid;grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:22px}
.card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:28px;transition:.25s}
.card:hover{box-shadow:var(--shadow-lg);border-color:transparent;transform:translateY(-4px)}
.card h3{font-size:1.15rem;margin-bottom:10px}
.card p{color:var(--slate);font-size:.94rem;margin-bottom:8px}
.card ul{list-style:none}
.card li{position:relative;padding-left:22px;margin-bottom:8px;color:var(--slate);font-size:.93rem}
.card li::before{content:"";position:absolute;left:0;top:9px;width:7px;height:7px;border-radius:50%;
  background:var(--brand);opacity:.5}
.card-more{margin-top:14px;color:var(--brand);font-weight:600;font-size:.92rem}
.ic-badge{width:50px;height:50px;border-radius:14px;background:var(--brand-soft);color:var(--brand);
  display:grid;place-items:center;margin-bottom:16px;font-size:1.4rem}
table{width:100%;border-collapse:collapse;margin:18px 0;font-size:.93rem;background:#fff;
  border:1px solid var(--line);border-radius:12px;overflow:hidden}
th,td{text-align:left;padding:12px 15px;border-bottom:1px solid var(--line)}
th{background:var(--brand-soft);font-weight:700;font-size:.75rem;text-transform:uppercase;
  letter-spacing:.06em;color:var(--brand-dark)}
tr:last-child td{border-bottom:none}
td strong{color:var(--ink)}
.callout{border-radius:14px;padding:20px 24px;margin:22px 0;font-size:.95rem}
.callout.warn{background:#fff7ed;border:1px solid #fed7aa;color:#7c2d12}
.callout.info{background:var(--brand-soft);border:1px solid #f0cfd6;color:var(--brand-dark)}
.callout.tip{background:#f0fdf4;border:1px solid #bbf7d0;color:#14532d}
.callout b{display:block;margin-bottom:5px}
.dos{display:grid;grid-template-columns:1fr 1fr;gap:20px;margin-top:8px}
.dos .col{border-radius:14px;padding:22px}
.dos .do{background:#f0fdf4;border:1px solid #bbf7d0}
.dos .dont{background:#fef2f2;border:1px solid #fecaca}
.dos h4{font-size:.78rem;letter-spacing:.1em;text-transform:uppercase;margin-bottom:12px;font-family:var(--sans);font-weight:700}
.dos .do h4{color:#14532d}.dos .dont h4{color:#991b1b}
.dos ul{list-style:none}
.dos li{padding:5px 0 5px 24px;position:relative;font-size:.92rem;line-height:1.55}
.dos .do li::before{content:"\2713";position:absolute;left:0;color:#16a34a;font-weight:700}
.dos .dont li::before{content:"\2715";position:absolute;left:0;color:#dc2626;font-weight:700}
.faq-list{max-width:820px;margin:0 auto;display:grid;gap:13px}
.faq-item{border:1px solid var(--line);border-radius:14px;background:#fff;overflow:hidden;transition:.2s}
.faq-item[open]{border-color:var(--brand);box-shadow:var(--shadow)}
.faq-item summary{list-style:none;cursor:pointer;padding:19px 24px;font-weight:600;font-size:1rem;
  display:flex;justify-content:space-between;align-items:center;gap:16px;min-height:44px}
.faq-item summary::-webkit-details-marker{display:none}
.faq-item summary::after{content:"+";font-family:var(--sans);font-size:1.5rem;color:var(--brand);
  flex-shrink:0;transition:.2s}
.faq-item[open] summary::after{transform:rotate(45deg)}
.faq-item .faq-a{padding:0 24px 20px;color:var(--slate);font-size:.95rem}
.faq-item .faq-a a{color:var(--brand);font-weight:600}
.doc-strip{background:linear-gradient(160deg,var(--brand) 0%,var(--brand-dark) 100%);color:#fff;
  border-radius:var(--radius);padding:34px;display:grid;grid-template-columns:auto 1fr auto;
  gap:26px;align-items:center;box-shadow:var(--shadow-lg)}
.doc-strip .ph{width:104px;height:104px;border-radius:50%;overflow:hidden;border:3px solid rgba(255,255,255,.4);
  flex-shrink:0;background:#fff}
.doc-strip .ph img{width:100%;height:100%;object-fit:cover}
.doc-strip h3{color:#fff;font-size:1.35rem;margin-bottom:4px}
.doc-strip .role{color:rgba(255,255,255,.85);font-size:.9rem;font-family:var(--sans);margin-bottom:8px}
.doc-strip p{color:rgba(255,255,255,.9);font-size:.92rem;max-width:520px}
.doc-strip .btn{background:#fff;color:var(--brand);white-space:nowrap}
.doc-strip .btn:hover{background:var(--sand)}
.cta-band{background:linear-gradient(160deg,var(--brand) 0%,var(--brand-dark) 100%);color:#fff;text-align:center}
.cta-band h2{color:#fff;font-size:clamp(1.6rem,3.2vw,2.2rem);margin-bottom:14px}
.cta-band p{color:rgba(255,255,255,.9);max-width:600px;margin:0 auto 26px}
.cta-band .hero-actions{justify-content:center}
.cta-band .btn-primary{background:#fff;color:var(--brand)}
.cta-band .btn-ghost{color:#fff;border-color:rgba(255,255,255,.6)}
.cta-band .btn-ghost:hover{background:rgba(255,255,255,.12)}
.refs{font-size:.86rem;color:var(--slate)}
.refs ol{margin-left:18px}
.refs li{margin-bottom:7px}
.refs a{color:var(--brand)}
.disclaimer{background:var(--sand);border:1px solid var(--line);border-radius:14px;padding:20px 24px;
  font-size:.87rem;color:var(--slate);margin-top:26px}
.disclaimer b{color:var(--ink)}
.updated{font-size:.83rem;color:var(--slate);margin-top:10px}
.fab{position:fixed;bottom:26px;right:26px;z-index:200;width:60px;height:60px;border-radius:50%;
  background:#25d366;display:grid;place-items:center;box-shadow:0 10px 30px rgba(37,211,102,.45);transition:.25s}
.fab:hover{transform:scale(1.08)}
footer{background:var(--ink);color:#d8cfd1;padding:52px 0 28px}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:38px;margin-bottom:36px}
.footer-brand{display:flex;align-items:center;gap:12px;margin-bottom:14px;color:#fff;
  font-family:var(--serif);font-size:1.2rem}
footer p{font-size:.9rem;color:#b0a1a4;max-width:340px}
footer h2{color:#fff;font-family:var(--sans);font-size:.78rem;letter-spacing:.12em;
  text-transform:uppercase;margin-bottom:14px;font-weight:600}
footer ul{list-style:none}
footer ul a{font-size:.92rem;color:#b0a1a4;display:inline-flex;align-items:center;min-height:38px;transition:.2s}
footer ul a:hover{color:#fff}
.footer-bottom{border-top:1px solid rgba(255,255,255,.12);padding-top:20px;text-align:center;
  font-size:.85rem;color:#9a8b8e}
/* ---------- CJK fallback (matches homepages) ---------- */
html[lang^="zh"] h1,html[lang^="zh"] h2,html[lang^="zh"] h3,html[lang^="zh"] h4{letter-spacing:0}
html[lang^="zh"] body,body:lang(zh){font-family:var(--sans),
  "Noto Sans SC","PingFang SC","Microsoft YaHei",sans-serif}
@media(max-width:900px){
  .nav-links{display:none}
  .menu-btn{display:grid;place-items:center}
  .nav-links.open{display:flex;position:absolute;top:74px;left:0;right:0;flex-direction:column;
    align-items:stretch;background:#fff;padding:12px 24px 20px;gap:4px;border-bottom:1px solid var(--line);
    box-shadow:var(--shadow)}
  .nav-links.open a{min-height:52px;padding:0 8px;border-bottom:1px solid var(--line)}
  .lang{display:none}
  section{padding:56px 0}
  .grid-2,.dos,.footer-grid{grid-template-columns:1fr}
  .doc-strip{grid-template-columns:1fr;text-align:center;justify-items:center}
  .doc-strip p{margin:0 auto}
}
@media(max-width:600px){
  .wrap{padding:0 18px}
  section{padding:46px 0}
  .card,.keyfacts{padding:22px}
  .brand small{display:none}
  .brand{font-size:1.05rem}
  .hero-actions .btn{width:100%}
  .fab{width:56px;height:56px;bottom:18px;right:18px}
  .keyfacts .kf{flex-direction:column;gap:2px}
  .keyfacts dt{min-width:0}
  table{font-size:.86rem}
  th,td{padding:10px 11px}
}
@media(prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}
@media print{header,.fab,.cta-band,footer{display:none}body{color:#000}}