:root{
  --paper:#f4f1e9;--paper-2:#ebe7dc;--ink:#172027;--muted:#5e666b;--rule:#c9c4b8;
  --navy:#18364f;--navy-2:#274f6d;--oxblood:#7c2933;--green:#335f50;--white:#fffdf8;
  --max:1180px;--reading:790px;--serif:Georgia,"Times New Roman","Noto Serif TC",serif;
  --sans:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans TC",sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);line-height:1.72;-webkit-font-smoothing:antialiased}
a{color:var(--navy);text-decoration:none}
a:hover{color:var(--oxblood)}
.wrap{width:min(calc(100% - 42px),var(--max));margin:0 auto}
.reading{width:min(100%,var(--reading))}
.site-header{position:sticky;top:0;z-index:50;background:rgba(244,241,233,.94);backdrop-filter:blur(16px);border-bottom:1px solid var(--rule)}
.nav{min-height:72px;display:flex;align-items:center;gap:24px}
.brand{display:flex;align-items:baseline;gap:9px;color:var(--ink);white-space:nowrap}
.brand-mark{font-family:var(--serif);font-weight:700;font-size:20px;letter-spacing:-.02em}
.brand-sub{font-size:11px;letter-spacing:.13em;text-transform:uppercase;color:var(--muted)}
.nav-links{display:flex;align-items:center;gap:18px;margin-left:auto}
.nav-links a{font-size:13px;color:var(--muted)}
.nav-links a.active,.nav-links a:hover{color:var(--ink)}
.lang-toggle{display:flex;border:1px solid var(--rule);padding:2px;background:var(--white)}
.lang-toggle button{border:0;background:transparent;padding:6px 9px;color:var(--muted);font-weight:700;cursor:pointer}
.lang-toggle button.active{background:var(--ink);color:var(--white)}
.paper-hero{padding:82px 0 54px;border-bottom:1px solid var(--rule)}
.kicker{font-size:12px;letter-spacing:.17em;text-transform:uppercase;color:var(--oxblood);font-weight:800}
h1,h2,h3,.serif{font-family:var(--serif)}
h1{font-size:clamp(44px,6.8vw,78px);line-height:1.02;letter-spacing:-.045em;margin:16px 0 22px;max-width:980px;font-weight:500}
.hero-dek{font-family:var(--serif);font-size:clamp(20px,2.3vw,27px);line-height:1.45;color:#39454d;max-width:900px;margin:0}
.research-meta{margin-top:38px;display:grid;grid-template-columns:repeat(4,1fr);border-top:1px solid var(--ink);border-bottom:1px solid var(--rule)}
.meta-item{padding:13px 16px 13px 0;border-right:1px solid var(--rule)}
.meta-item:last-child{border-right:0;padding-left:16px}
.meta-label{font-size:10px;letter-spacing:.12em;text-transform:uppercase;color:var(--muted);font-weight:800}
.meta-value{font-family:var(--serif);font-size:16px;margin-top:3px}
section{padding:64px 0;border-bottom:1px solid var(--rule)}
.section-head{display:grid;grid-template-columns:110px minmax(0,760px);gap:28px;align-items:start;margin-bottom:30px}
.sec-no{font-family:var(--serif);font-size:13px;color:var(--oxblood);padding-top:8px}
.section-head h2{font-size:clamp(31px,4vw,47px);font-weight:500;line-height:1.12;letter-spacing:-.025em;margin:0 0 12px}
.section-head p{margin:0;color:var(--muted);font-size:17px}
.abstract{background:var(--white);border-top:3px solid var(--ink);border-bottom:1px solid var(--rule);padding:28px 32px;margin-top:40px;max-width:980px}
.abstract-label{font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--oxblood);font-weight:800;margin-bottom:9px}
.abstract p{font-family:var(--serif);font-size:19px;line-height:1.65;margin:0}
.two-col{display:grid;grid-template-columns:1fr 1fr;gap:34px}
.three-col{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.four-col{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}
.paper-card{background:var(--white);border:1px solid var(--rule);padding:24px}
.paper-card .index{font-size:11px;letter-spacing:.13em;text-transform:uppercase;color:var(--oxblood);font-weight:800}
.paper-card h3{font-size:23px;line-height:1.22;margin:10px 0 9px;font-weight:500}
.paper-card p{color:var(--muted);margin:0}
.claim-box{border-left:4px solid var(--navy);padding:4px 0 4px 22px;margin:26px 0}
.claim-box p{font-family:var(--serif);font-size:23px;line-height:1.48;margin:0}
.scope-note{background:#e8ecee;border:1px solid #c5cdd2;padding:22px 24px;margin-top:26px}
.scope-note strong{font-family:var(--serif);font-size:18px}
.workflow{display:grid;grid-template-columns:repeat(5,1fr);border-top:1px solid var(--ink);border-left:1px solid var(--rule);margin-top:24px}
.workflow-step{min-height:120px;padding:18px 16px;border-right:1px solid var(--rule);border-bottom:1px solid var(--rule);background:rgba(255,253,248,.55)}
.workflow-step .n{font-size:10px;color:var(--oxblood);font-weight:800;letter-spacing:.12em}
.workflow-step strong{display:block;font-family:var(--serif);font-size:17px;line-height:1.25;margin-top:18px}
.evidence-table{width:100%;border-collapse:collapse;margin-top:22px;background:var(--white)}
.evidence-table th,.evidence-table td{border-bottom:1px solid var(--rule);padding:14px 12px;text-align:left;vertical-align:top}
.evidence-table th{font-size:10px;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);border-top:1px solid var(--ink)}
.evidence-table td:first-child{font-family:var(--serif);font-weight:600}
.metric{border-top:3px solid var(--ink);padding:18px 8px 10px 0}
.metric .n{font-family:var(--serif);font-size:42px;line-height:1;color:var(--navy)}
.metric .label{font-size:12px;color:var(--muted);margin-top:8px}
.figure{margin:30px 0;background:var(--white);border:1px solid var(--rule);padding:26px}
.figure-title{font-family:var(--serif);font-size:18px;margin-bottom:20px}
.figure-caption{font-size:12px;color:var(--muted);border-top:1px solid var(--rule);margin-top:20px;padding-top:12px}
.arrow-flow{display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.flow-box{border:1px solid var(--ink);padding:16px 18px;background:var(--paper);font-family:var(--serif)}
.arrow{font-size:25px;color:var(--oxblood)}
.note{font-size:13px;color:var(--muted)}
.artifact-links{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}
.artifact-links a{border-bottom:1px solid var(--navy);font-size:13px}
.audience-list{display:grid;grid-template-columns:repeat(2,1fr);gap:0;border-top:1px solid var(--ink)}
.audience-item{padding:20px 20px 20px 0;border-bottom:1px solid var(--rule)}
.audience-item:nth-child(odd){border-right:1px solid var(--rule);padding-right:26px}
.audience-item:nth-child(even){padding-left:26px}
.audience-item h3{font-size:20px;margin:0 0 6px}
.audience-item p{margin:0;color:var(--muted)}
.limitations{background:#eeeae0;padding:26px;border:1px solid var(--rule)}
.limitations h3{margin:0 0 12px;font-size:21px}
.limitations ul{margin:0;padding-left:20px;color:var(--muted)}
.cta-section{background:var(--ink);color:var(--white);padding:74px 0}
.cta-section .section-head{margin-bottom:34px}
.cta-section .sec-no{color:#dba8ad}
.cta-section .section-head h2{color:var(--white)}
.cta-section .section-head p{color:#b8c1c7}
.cta-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.cta-card{display:flex;flex-direction:column;min-height:330px;padding:26px;border:1px solid #465057;background:#202a31}
.cta-card .badge{font-size:10px;text-transform:uppercase;letter-spacing:.13em;color:#d8b0b5;font-weight:800}
.cta-card h3{font-size:27px;font-weight:500;line-height:1.15;margin:14px 0 10px}
.cta-card p{color:#c8d0d5;margin:0 0 24px}
.cta-card .cta-action{margin-top:auto}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:46px;padding:0 16px;border:1px solid #d6dadd;background:transparent;color:var(--white);font-weight:800;font-size:13px}
.btn:hover{background:var(--white);color:var(--ink)}
.btn.primary{background:var(--white);color:var(--ink)}
.btn.disabled{opacity:.52;cursor:not-allowed}
.research-note-hero{padding:70px 0 42px;border-bottom:1px solid var(--rule)}
.research-note-hero h1{font-size:clamp(40px,6vw,68px)}
.breadcrumbs{font-size:12px;color:var(--muted);margin-bottom:30px}
.breadcrumbs a{color:var(--muted)}
.result-emphasis{font-family:var(--serif);font-size:27px;line-height:1.45;border-top:1px solid var(--ink);border-bottom:1px solid var(--rule);padding:22px 0;margin:26px 0}
.form-shell{display:grid;grid-template-columns:minmax(0,720px) 1fr;gap:48px;align-items:start}
.intake-form{background:var(--white);border-top:3px solid var(--ink);padding:28px}
.form-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.field{display:flex;flex-direction:column;gap:7px}
.field.full{grid-column:1/-1}
.field label{font-size:12px;font-weight:800;letter-spacing:.03em}
.field input,.field textarea,.field select{width:100%;border:1px solid #bdb8ac;background:#fffefb;padding:11px 12px;font:inherit;color:var(--ink);border-radius:0}
.field textarea{min-height:118px;resize:vertical}
.field small{color:var(--muted)}
.checkbox{display:flex;gap:9px;align-items:flex-start;font-size:13px;color:var(--muted)}
.form-status{margin-top:14px;padding:12px 14px;border:1px solid var(--rule);display:none}
.form-status.show{display:block}
.form-status.error{border-color:#b66;background:#f6e8e6}
.form-status.success{border-color:#6a9;background:#e6f0eb}
.form-side{position:sticky;top:98px}
.form-side .paper-card{margin-bottom:16px}
footer{padding:34px 0 44px;color:var(--muted);font-size:12px}
.footer-row{display:flex;justify-content:space-between;gap:22px;flex-wrap:wrap}
[data-lang]{display:none}
html[data-language="en"] [data-lang="en"]{display:block}
html[data-language="zh"] [data-lang="zh"]{display:block}
span[data-lang],a[data-lang],td[data-lang],th[data-lang]{display:none}
html[data-language="en"] span[data-lang="en"],html[data-language="en"] a[data-lang="en"]{display:inline}
html[data-language="zh"] span[data-lang="zh"],html[data-language="zh"] a[data-lang="zh"]{display:inline}
html[data-language="en"] td[data-lang="en"],html[data-language="en"] th[data-lang="en"]{display:table-cell}
html[data-language="zh"] td[data-lang="zh"],html[data-language="zh"] th[data-lang="zh"]{display:table-cell}
@media(max-width:980px){
  .nav-links a:not(.keep){display:none}
  .research-meta,.four-col,.cta-grid{grid-template-columns:repeat(2,1fr)}
  .workflow{grid-template-columns:repeat(2,1fr)}
  .three-col{grid-template-columns:1fr}
  .form-shell{grid-template-columns:1fr}
  .form-side{position:static}
}
@media(max-width:680px){
  .wrap{width:min(calc(100% - 26px),var(--max))}
  .paper-hero{padding-top:55px}
  h1{font-size:43px}
  .section-head{grid-template-columns:1fr;gap:5px}
  .two-col,.research-meta,.four-col,.cta-grid,.form-grid{grid-template-columns:1fr}
  .meta-item{border-right:0;border-bottom:1px solid var(--rule);padding:12px 0}
  .meta-item:last-child{padding-left:0;border-bottom:0}
  .workflow{grid-template-columns:1fr}
  .audience-list{grid-template-columns:1fr}
  .audience-item:nth-child(odd){border-right:0;padding-right:0}
  .audience-item:nth-child(even){padding-left:0}
  .brand-sub{display:none}
  .nav{gap:10px}
}

/* FAQ / AEO */
.faq-list{display:grid;gap:12px;max-width:980px}
.faq-list details{border-top:1px solid var(--line);padding:16px 0}
.faq-list details:last-child{border-bottom:1px solid var(--line)}
.faq-list summary{cursor:pointer;font-weight:700;font-size:1.02rem;list-style:none;padding-right:32px;position:relative}
.faq-list summary::-webkit-details-marker{display:none}
.faq-list summary::after{content:"+";position:absolute;right:4px;top:-2px;font-size:1.3rem;font-weight:400}
.faq-list details[open] summary::after{content:"−"}
.faq-list details p{max-width:820px;margin:12px 0 0;color:var(--muted);line-height:1.75}