:root{
  --ink:#101820;
  --muted:#566675;
  --navy:#0b2f4f;
  --blue:#155e9a;
  --teal:#1d6b6a;
  --signal:#bd3e36;
  --steel:#8fa0ad;
  --line:#d6e0e7;
  --wash:#f3f7fa;
  --paper:#ffffff;
  --deep:#071a2a;
  --max:1240px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:Inter,"IBM Plex Sans",system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;line-height:1.58}
a{color:inherit;text-decoration:none}
a:hover{text-decoration:underline;text-underline-offset:4px}
img{display:block;max-width:100%}
.wrap{width:min(var(--max),calc(100% - 48px));margin:0 auto}
.utility{background:var(--deep);color:#dbe7ef;font-size:.77rem;letter-spacing:.09em;text-transform:uppercase}
.utility .wrap{display:flex;justify-content:space-between;align-items:center;min-height:35px}
.utility a{opacity:.86}.utility a:hover{opacity:1}
.masthead{border-bottom:1px solid var(--line);background:#fff}
.masthead-row{display:flex;align-items:center;justify-content:space-between;gap:32px;min-height:98px}
.brand{display:flex;align-items:center;gap:14px;min-width:320px;text-decoration:none!important}
.brand img{width:47px;height:47px;object-fit:contain}
.brand-name{display:block;font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.72rem;line-height:1;letter-spacing:.015em;color:var(--navy)}
.brand-sub{display:block;margin-top:7px;color:#52606c;font-size:.68rem;letter-spacing:.15em;text-transform:uppercase}
.nav{display:flex;gap:27px;align-items:center;font-size:.9rem;color:#223544;white-space:nowrap}
.nav a[aria-current="page"]{font-weight:700;color:var(--blue)}
.hero{border-bottom:1px solid var(--line);overflow:hidden}
.hero-grid{display:grid;grid-template-columns:minmax(0,1.17fr) minmax(360px,.83fr);min-height:550px}
.hero-copy{padding:72px 70px 66px 0;display:flex;flex-direction:column;justify-content:center}
.eyebrow,.kicker{font-size:.76rem;letter-spacing:.16em;text-transform:uppercase;font-weight:700;color:var(--blue)}
.hero h1{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:clamp(3.4rem,6vw,6.3rem);font-weight:500;letter-spacing:-.045em;line-height:.92;margin:18px 0 28px;color:var(--deep)}
.hero .lede{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.35rem;line-height:1.55;max-width:760px;margin:0;color:#263946}
.hero-actions{display:flex;gap:22px;margin-top:34px;align-items:center;font-size:.88rem;font-weight:700}
.hero-actions .primary{background:var(--blue);color:#fff;padding:12px 17px;text-decoration:none}
.hero-actions .secondary{color:var(--navy)}
.hero-mark-panel{background:linear-gradient(150deg,#eef5f8 0%,#f8fbfc 46%,#e7f0f4 100%);border-left:1px solid var(--line);display:flex;align-items:center;justify-content:center;padding:65px}
.hero-mark-panel img{width:min(440px,82%);filter:drop-shadow(0 18px 28px rgba(17,47,74,.08))}
.measure-rule{height:33px;border-bottom:1px solid var(--line);background:
 linear-gradient(to right,transparent 0,transparent 9px,var(--steel) 9px,var(--steel) 10px,transparent 10px,transparent 20px) left 18px/20px 8px repeat-x;
 opacity:.7}
.section{padding:72px 0;border-bottom:1px solid var(--line)}
.section.alt{background:var(--wash)}
.section.dark{background:var(--deep);color:#fff}
.section-grid{display:grid;grid-template-columns:210px minmax(0,1fr);gap:52px}
.section h2,.page-head h1{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-weight:500;letter-spacing:-.025em;line-height:1.06;color:var(--deep);margin:0 0 22px}
.section h2{font-size:clamp(2.35rem,4vw,4rem)}
.section.dark h2,.section.dark .kicker{color:#fff}
.section p{max-width:820px}
.large{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.45rem;line-height:1.55;color:#2a3c49}
.section.dark .large{color:#e9f1f6}
.intro-grid{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(300px,.8fr);gap:58px;align-items:start}
.definition{border-left:4px solid var(--blue);padding:3px 0 3px 24px;font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.42rem;line-height:1.5;color:#213746}
.topic-grid{display:grid;grid-template-columns:repeat(4,1fr);border-top:1px solid var(--line);border-left:1px solid var(--line)}
.topic{min-height:170px;padding:25px 24px;border-right:1px solid var(--line);border-bottom:1px solid var(--line);background:#fff;transition:background .18s ease}
.topic:hover{background:#f6fafc;text-decoration:none}
.topic span{display:block;color:var(--blue);font-size:.72rem;font-weight:700;letter-spacing:.13em;text-transform:uppercase;margin-bottom:13px}
.topic h3{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.35rem;font-weight:500;margin:0 0 8px;color:var(--deep)}
.topic p{font-size:.88rem;color:var(--muted);margin:0}
.logic{display:grid;grid-template-columns:1fr 55px 1fr 55px 1fr;align-items:stretch;margin-top:34px}
.logic-block{border:1px solid #cbd8e1;background:#fff;padding:26px 25px;min-height:225px}
.logic-block strong{display:block;font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.4rem;color:var(--navy);font-weight:500;margin-bottom:12px}
.logic-arrow{display:flex;align-items:center;justify-content:center;font-size:1.8rem;color:var(--steel)}
.matrix{display:grid;grid-template-columns:repeat(9,1fr);gap:7px;margin-top:20px; margin: auto;}
.matrix i{width:14px;height:14px;border-radius:50%;background:#d7e1e8;display:block}
.matrix i.on{background:var(--blue)}
.axis-mini{margin-top:18px;height:84px;position:relative}
.axis-mini:before{content:"";position:absolute;left:8%;right:8%;top:43px;border-top:2px solid var(--navy)}
.axis-mini .tick{position:absolute;top:36px;width:1px;height:16px;background:#8195a5}
.axis-mini .dot{position:absolute;top:34px;width:18px;height:18px;border-radius:50%;background:var(--teal);transform:translateX(-9px)}
.axis-mini .square{position:absolute;top:36px;width:14px;height:14px;background:var(--navy);transform:translateX(-7px)}
.prob{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:2.2rem;color:var(--navy);margin-top:27px}
.prob small{display:block;font-family:Inter,system-ui,sans-serif;font-size:.82rem;color:var(--muted);margin-top:9px}
.quote-band{background:var(--navy);color:white;padding:38px 0}
.quote-band .wrap{display:grid;grid-template-columns:210px 1fr;gap:52px;align-items:start}
.quote-band blockquote{margin:0;font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:clamp(1.7rem,3vw,2.75rem);line-height:1.25;max-width:980px}
.work-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.work{border-top:3px solid var(--navy);padding-top:16px}
.work .meta,.pub-meta{font-size:.72rem;letter-spacing:.1em;text-transform:uppercase;color:var(--blue);font-weight:700}
.work h3{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.55rem;line-height:1.22;font-weight:500;margin:12px 0;color:var(--deep)}
.work p{font-size:.92rem;color:var(--muted)}
.work a{font-size:.82rem;font-weight:700;color:var(--blue)}
.publications{border-top:1px solid var(--line)}
.pub{display:grid;grid-template-columns:120px 1fr 120px;gap:28px;padding:25px 0;border-bottom:1px solid var(--line);align-items:start}
.pub h3{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.32rem;font-weight:500;margin:0 0 8px;color:var(--deep)}
.pub p{margin:0;font-size:.88rem;color:var(--muted)}
.pub-link{text-align:right;font-size:.82rem;font-weight:700;color:var(--blue)}
.page-head{background:var(--wash);border-bottom:1px solid var(--line);padding:65px 0}
.page-head-grid{display:grid;grid-template-columns:210px 1fr;gap:52px}
.page-head h1{font-size:clamp(3rem,5vw,5.4rem);max-width:930px}
.page-head p{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.35rem;max-width:820px;color:#304554}
.prose{max-width:930px}
.prose h3{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.55rem;font-weight:500;color:var(--deep);margin:32px 0 10px}
.prose ul{padding-left:20px}.prose li{margin:.5em 0}
.equation{font-family:"STIX Two Math","Cambria Math",Georgia,serif;font-size:1.45rem;padding:20px 22px;background:#eef4f7;border-left:3px solid var(--blue);margin:26px 0;color:var(--navy)}
.institute-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:25px;margin-top:30px}
.institute-grid div{border-top:2px solid var(--navy);padding-top:16px}
.institute-grid h3{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.4rem;font-weight:500;margin:0 0 10px;color:var(--deep)}
.institute-grid p{font-size:.9rem;color:var(--muted)}
.footer{background:var(--deep);color:#d5e1e9;padding:48px 0 28px;margin-top:0}
.footer-top{display:grid;grid-template-columns:1.3fr repeat(3,.6fr);gap:34px}
.footer-name{font-family:Charter,"Bitstream Charter","Iowan Old Style",Georgia,serif;font-size:1.65rem;color:#fff}
.footer-name span{display:block;font-family:Inter,system-ui,sans-serif;font-size:.67rem;letter-spacing:.14em;text-transform:uppercase;color:#9eb4c2;margin-top:7px}
.footer h4{font-size:.73rem;letter-spacing:.14em;text-transform:uppercase;color:#fff;margin:0 0 13px}
.footer a{display:block;font-size:.84rem;margin:7px 0;color:#bfd0db}
.footer-bottom{border-top:1px solid #29465b;margin-top:34px;padding-top:18px;font-size:.75rem;color:#8eabba}
@media(max-width:900px){
 .masthead-row{align-items:flex-start;padding:20px 0;min-height:auto}.nav{display:none}.brand{min-width:0}.hero-grid,.section-grid,.page-head-grid,.intro-grid,.quote-band .wrap{grid-template-columns:1fr}.hero-copy{padding:52px 0 40px}.hero-mark-panel{border-left:0;border-top:1px solid var(--line);min-height:380px}.topic-grid{grid-template-columns:repeat(2,1fr)}.logic{grid-template-columns:1fr}.logic-arrow{height:45px;transform:rotate(90deg)}.work-grid,.institute-grid{grid-template-columns:1fr}.pub{grid-template-columns:90px 1fr}.pub-link{grid-column:2;text-align:left}.footer-top{grid-template-columns:1fr 1fr}.section-grid,.page-head-grid,.quote-band .wrap{gap:22px}.kicker{margin-bottom:4px}
}
@media(max-width:560px){.wrap{width:min(var(--max),calc(100% - 28px))}.hero h1{font-size:3rem}.hero .lede{font-size:1.15rem}.hero-mark-panel{padding:40px}.topic-grid{grid-template-columns:1fr}.utility .wrap{font-size:.64rem}.footer-top{grid-template-columns:1fr}.brand-sub{letter-spacing:.1em}.brand-name{font-size:1.4rem}}
/* v9.2: broader research record */
@media(min-width:901px){.work-grid{grid-template-columns:repeat(2,1fr)}}
.research-lineage .topic{min-height:220px}
.pub-link span{font-size:.78rem;color:var(--muted)}

/* Ambient scientific geometry — viewport-level, intentionally non-semantic. */
.ambient-geometry{
  position:fixed;
  inset:-2.5vh -2.5vw;
  z-index:0;
  pointer-events:none;
  background:url("assets/ambient-geometry.svg") center/cover no-repeat;
  opacity:.72;
  transform:translate3d(0,0,0) scale(1.015);
  animation:ambient-drift 34s ease-in-out infinite alternate;
}
.utility,.masthead,main,.footer{position:relative;z-index:1}
/* Most content remains exactly as before; the geometry is visible only through
   existing transparent regions and page gutters. */
@keyframes ambient-drift{
  from{transform:translate3d(-5px,-3px,0) scale(1.012)}
  to{transform:translate3d(7px,5px,0) scale(1.022)}
}
@media (prefers-reduced-motion:reduce){
  .ambient-geometry{animation:none;transform:none}
}

/* v9.4 — light/dark institutional themes. No layout or copy changes. */
:root{
  color-scheme:light dark;
  --surface:#ffffff;
  --surface-soft:#f3f7fa;
  --surface-raised:#ffffff;
  --text:#101820;
  --text-soft:#566675;
  --text-strong:#071a2a;
  --header:#ffffff;
  --header-rule:#d6e0e7;
  --link:#155e9a;
  --accent:#1d6b6a;
  --utility:#071a2a;
  --utility-text:#dbe7ef;
  --footer:#071a2a;
  --footer-rule:#29465b;
  --footer-text:#d5e1e9;
  --quote:#0b2f4f;
  --quote-kicker:#a9c7da;
  --panel-line:#cbd8e1;
  --hero-a:#eef5f8;
  --hero-b:#f8fbfc;
  --hero-c:#e7f0f4;
  --equation:#eef4f7;
  --mark-shadow:rgba(17,47,74,.08);
}
html[data-theme="dark"]{
  --ink:#e7edf2;
  --muted:#9db0be;
  --navy:#9fd3ef;
  --blue:#72b9e6;
  --teal:#6ec5bd;
  --signal:#ef766d;
  --steel:#718593;
  --line:#263845;
  --wash:#101b24;
  --paper:#0b1218;
  --deep:#071017;

  --surface:#0b1218;
  --surface-soft:#101b24;
  --surface-raised:#111c25;
  --text:#e7edf2;
  --text-soft:#9db0be;
  --text-strong:#f6f9fb;
  --header:#0d161e;
  --header-rule:#263845;
  --link:#72b9e6;
  --accent:#6ec5bd;
  --utility:#050b10;
  --utility-text:#b9cad5;
  --footer:#050b10;
  --footer-rule:#213542;
  --footer-text:#b9c9d3;
  --quote:#0b2636;
  --quote-kicker:#8fc3df;
  --panel-line:#2b404e;
  --hero-a:#0e1c26;
  --hero-b:#12242f;
  --hero-c:#0a171f;
  --equation:#13222c;
  --mark-shadow:rgba(0,0,0,.32);
}

body{background:var(--surface);color:var(--text)}
.utility{background:var(--utility);color:var(--utility-text)}
.masthead{background:var(--header);border-color:var(--header-rule)}
.brand-name,.hero h1,.section h2,.page-head h1,.topic h3,.work h3,.pub h3,.prose h3,.institute-grid h3{color:var(--text-strong)}
.brand-sub{color:var(--text-soft)}
.nav{color:var(--text)}
.nav a[aria-current="page"]{color:var(--link)}
.hero,.section,.page-head{border-color:var(--line)}
.hero .lede,.large,.definition,.page-head p{color:color-mix(in srgb,var(--text) 88%,var(--text-soft))}
.hero-actions .secondary,.logic-block strong,.prob{color:var(--navy)}
.hero-actions .primary{background:var(--link)}
.hero-mark-panel{background:linear-gradient(150deg,var(--hero-a) 0%,var(--hero-b) 46%,var(--hero-c) 100%);border-color:var(--line)}
.hero-mark-panel img{filter:drop-shadow(0 18px 28px var(--mark-shadow))}
.section.alt,.page-head{background:var(--surface-soft)}
.topic,.logic-block{background:var(--surface-raised);border-color:var(--line)}
.topic:hover{background:color-mix(in srgb,var(--surface-soft) 82%,var(--link) 18%)}
.topic p,.work p,.pub p,.institute-grid p,.prob small,.pub-link span{color:var(--text-soft)}
.definition{border-color:var(--link)}
.logic-block{border-color:var(--panel-line)}
.matrix i{background:color-mix(in srgb,var(--surface-soft) 75%,var(--steel) 25%)}
.matrix i.on{background:var(--link)}
.axis-mini:before{border-color:var(--navy)}
.axis-mini .tick{background:var(--steel)}
.axis-mini .dot{background:var(--accent)}
.axis-mini .square{background:var(--navy)}
.quote-band{background:var(--quote)}
.quote-band .kicker{color:var(--quote-kicker)!important}
.work{border-color:var(--navy)}
.work a,.pub-link,.kicker,.eyebrow{color:var(--link)}
.publications,.pub,.measure-rule{border-color:var(--line)}
.equation{background:var(--equation);border-color:var(--link);color:var(--navy)}
.institute-grid div{border-color:var(--navy)}
.footer{background:var(--footer);color:var(--footer-text)}
.footer-bottom{border-color:var(--footer-rule)}

.theme-toggle{
  appearance:none;
  border:1px solid var(--line);
  background:transparent;
  color:var(--text);
  width:38px;
  height:38px;
  border-radius:50%;
  display:inline-grid;
  place-items:center;
  cursor:pointer;
  padding:0;
  flex:0 0 auto;
  transition:background .16s ease,border-color .16s ease,transform .16s ease;
}
.theme-toggle:hover{background:var(--surface-soft);border-color:var(--steel);transform:translateY(-1px)}
.theme-toggle svg{width:18px;height:18px;stroke:currentColor;fill:none;stroke-width:1.65;stroke-linecap:round;stroke-linejoin:round}
.theme-toggle .moon{display:none}
html[data-theme="dark"] .theme-toggle .sun{display:none}
html[data-theme="dark"] .theme-toggle .moon{display:block}

/* Keep the floating geometry legible but subordinate in either theme. */
html[data-theme="dark"] .ambient-geometry{opacity:.52;filter:brightness(1.75) saturate(.72) hue-rotate(3deg)}

@media(max-width:900px){
  .masthead-row{gap:18px}
  .theme-toggle{margin-left:auto}
}

/* v9.5 — theme-correct mark and live viewport visualization. */
html[data-theme="dark"] img[src$="latent-trait-mark.png"]{
  content:url("assets/latent-trait-mark-light.png");
}
.ambient-canvas{
  position:fixed;
  inset:0;
  width:100vw;
  height:100vh;
  z-index:0;
  pointer-events:none;
}
.js .ambient-geometry{display:none}
html:not(.js) .ambient-canvas{display:none}
html[data-theme="dark"] .hero-mark-panel img{
  filter:drop-shadow(0 18px 30px rgba(0,0,0,.34));
}