:root{
  --paper:#f4f1e9;
  --ink:#151714;
  --muted:#74776e;
  --line:#c9c7bc;
  --accent:#5f7339;
  --card:rgba(255,255,255,.16);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:Georgia,'Times New Roman',serif}
a{color:inherit;text-decoration:none}
button{font:inherit;color:inherit}

header{
  height:62px;
  margin:0 4.55%;
  display:flex;
  align-items:center;
  justify-content:space-between;
  border-bottom:1px solid var(--line);
  font-family:Arial,sans-serif;
  letter-spacing:.22em;
  font-size:11px;
}
.brand{font-size:15px;font-weight:700}
nav{display:flex;align-items:center;gap:36px;font-weight:700}
.nav-divider{height:21px;border-left:1px solid var(--line);margin-left:-8px}
.theme-icon{border:0;background:none;padding:0;font-size:22px;line-height:1;cursor:pointer;font-weight:400}

main{width:74.2%;max-width:1320px;margin:auto}
.hero{
  min-height:302px;
  padding:34px 1.1% 22px;
  display:grid;
  grid-template-columns:.92fr 1.08fr;
  align-items:center;
  gap:90px;
}
.hero-copy{align-self:center}
.hero h1{
  font-weight:400;
  font-size:clamp(68px,5.25vw,92px);
  line-height:.79;
  margin:0 0 23px;
  letter-spacing:-.046em;
}
.hero h1 span{display:block}
.hero h1 span+span{margin-top:.08em}
.kicker{font:700 11px Arial,sans-serif;letter-spacing:.25em;margin:0}
.kicker span{padding:0 11px}
.rule,.mini-rule{width:23px;border-top:1px solid #8d927f}
.rule{margin:15px 0 18px}
.mini-rule{margin:12px 0 13px}
.intro{font-size:18px;line-height:1.35;max-width:360px;margin:0}

.sequence{text-align:center;font-size:25px;padding-top:2px}
.terms{display:flex;justify-content:center;gap:23px}
.accent,.formula,.math-expression span:first-child{color:var(--accent)}
.fade{opacity:.34}
.dots{font-size:17px;margin:13px auto 0;display:grid;grid-template-columns:repeat(7,1fr);align-items:center;width:286px;letter-spacing:0}
.dot{color:var(--ink)}
.dot-6{color:#aeb59a}
.dot-7{color:#889967}
.resolve{margin-top:28px;display:flex;justify-content:center;align-items:center;gap:59px}
.arrow{font-size:38px;color:var(--accent);font-weight:200}
.formula{display:inline-flex;flex-direction:column;align-items:center;min-width:128px;font-size:32px;line-height:1.06}
.formula .numerator{display:block;padding:0 7px 5px;border-bottom:1px solid var(--accent);white-space:nowrap}
.formula .denominator{display:block;padding-top:5px;font-size:.9em}

.section-label{
  text-align:center;
  font:700 10px Arial,sans-serif;
  letter-spacing:.22em;
  margin:0 0 14px;
  display:flex;
  justify-content:center;
  align-items:center;
  gap:14px;
}
.section-label span{font:400 15px Georgia,serif;letter-spacing:0}
.cards{display:grid;grid-template-columns:1fr 1fr;gap:14px;align-items:stretch}
.card{
  border:1px solid var(--line);
  padding:21px 20px 19px;
  background:var(--card);
  min-height:508px;
  display:flex;
  flex-direction:column;
}
.eyebrow,.subhead,.tags{font-family:Arial,sans-serif;font-weight:700;letter-spacing:.15em;color:#52613a}
.eyebrow{font-size:9px;margin:0}
.card h2{font-size:31px;font-weight:400;line-height:1.04;margin:10px 0 6px;letter-spacing:-.015em}
.subhead{font-size:8.5px;color:var(--ink);margin:0}
.card>p:not(.eyebrow):not(.subhead):not(.tags):not(.meta){font-size:14px;line-height:1.42;max-width:590px;margin-top:0}
.software img{width:100%;display:block;margin:13px 0 9px;border:1px solid #b8b9b3}
.tags{font-size:8.5px;margin:3px 0 11px}
.actions{display:flex;gap:13px;flex-wrap:wrap;margin-top:auto}
.actions a{
  border:1px solid #8f947e;
  padding:10px 18px;
  font:700 8.5px Arial,sans-serif;
  letter-spacing:.14em;
  transition:background .18s ease,transform .18s ease;
}
.actions a:hover{background:#e9e7dd;transform:translateY(-1px)}
.meta{font-size:13px;margin:0 0 13px}
.research{padding-right:25px}
.research h2{font-size:31px}
.math-mark{flex:1;min-height:198px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:17px}
.math-expression{display:flex;align-items:center;justify-content:center;gap:33px;font-size:42px}
.math-expression .relation{color:var(--ink);font-size:.78em}
.math-mark sub{font-size:.46em;vertical-align:-.12em}
.math-mark small{font:9px Arial,sans-serif;letter-spacing:.12em;color:var(--muted);text-transform:uppercase}
.research-actions{justify-content:center;margin-top:0}

.about{
  margin-top:13px;
  border-top:1px solid #dedbd0;
  border-bottom:1px solid #dedbd0;
  padding:18px 1.8%;
  display:grid;
  grid-template-columns:.5fr 1.45fr 1.45fr 1.05fr;
  gap:29px;
  align-items:start;
}
.about h3{font:700 10px Arial,sans-serif;letter-spacing:.22em;color:#465330;margin:2px 0 0}
.about p{font-size:12.5px;line-height:1.42;margin:0}
.about>div{display:flex;gap:12px;align-items:center}
.about b{font:700 8.5px Arial,sans-serif;letter-spacing:.18em}
.column-icon{font-size:25px;color:#627547}
footer{text-align:center;padding:16px;font-size:11px;letter-spacing:.06em}

@media(max-width:1200px){
  main{width:82%}
  .hero{gap:60px}
}
@media(max-width:900px){
  header{margin:0 4%}
  nav{gap:18px}
  .nav-divider{display:none}
  .theme-icon{display:inline-flex;align-items:center;justify-content:center;flex:0 0 auto}
  main{width:92%}
  .hero{grid-template-columns:1fr;padding-top:42px;min-height:auto;gap:30px}
  .sequence{padding:20px 0 8px}
  .cards{grid-template-columns:1fr}
  .about{grid-template-columns:1fr}
  .card{min-height:auto}
  .math-mark{min-height:185px}
  .research{padding-right:20px}
}
@media(max-width:600px){
  header{height:auto;padding:18px 0;align-items:flex-start}
  .brand{font-size:13px}
  nav{gap:11px;flex-wrap:wrap;justify-content:flex-end;font-size:8px}
  .hero{padding-left:0;padding-right:0}
  .hero h1{font-size:64px}
  .terms{gap:11px;font-size:20px}
  .dots{width:248px}
  .resolve{gap:28px}
  .formula{font-size:29px;min-width:115px}
  .card{padding:20px 16px}
  .card h2,.research h2{font-size:28px}
  .actions a{flex:1;text-align:center;padding:11px 8px}
  .intro{font-size:17px}
  .about{padding:24px 0}
  .about p{font-size:14px}
  .math-expression{font-size:38px;gap:24px}
}

/* v4 — restore the more structured About strip from the approved reference */
.about{
  margin-top:13px;
  border-top:1px solid #dedbd0;
  border-bottom:1px solid #dedbd0;
  padding:17px 1.8% 18px;
  grid-template-columns:.48fr 1.42fr 1.42fr 1.12fr;
  gap:0;
  align-items:center;
}
.about h3{
  align-self:start;
  padding-top:2px;
}
.about > p,
.about > div{
  min-height:49px;
  border-left:1px solid #d2cfc4;
  padding-left:31px;
  padding-right:27px;
  display:flex;
  align-items:center;
}
.about > div{
  gap:15px;
  padding-right:0;
}
.about > div p{display:block}
.about p{font-size:12.5px;line-height:1.42;margin:0}
.column-icon{
  font-size:27px;
  line-height:1;
  color:#627547;
  flex:0 0 auto;
}
@media(max-width:900px){
  .about{gap:18px}
  .about > p,.about > div{border-left:0;padding-left:0;padding-right:0;min-height:0}
}

/* v10 — functional theme control and honest handling of external links not yet supplied */
html[data-theme="dark"]{
  --paper:#171915;
  --ink:#efede4;
  --muted:#a7aa9f;
  --line:#4a4e43;
  --accent:#9aad67;
  --card:rgba(255,255,255,.025);
}

/* v13 — softer dark-mode progression for the sequence dots */
html[data-theme="dark"] .dot-1,
html[data-theme="dark"] .dot-2,
html[data-theme="dark"] .dot-3,
html[data-theme="dark"] .dot-4,
html[data-theme="dark"] .dot-5{color:#efede4}
html[data-theme="dark"] .dot-6{color:#bdc89c}
html[data-theme="dark"] .dot-7{color:#9aad67}

html[data-theme="dark"] .actions a:hover{background:#24281f}
html[data-theme="dark"] .research-actions a:hover{background:#24281f}
html[data-theme="dark"] .software img{border-color:#4a4e43}
html[data-theme="dark"] .about{border-color:#383b34}
html[data-theme="dark"] .about > p,
html[data-theme="dark"] .about > div{border-color:#44483e}
html[data-theme="dark"] .eyebrow,
html[data-theme="dark"] .tags{color:#9aad67}
html[data-theme="dark"] .subhead{color:var(--ink)}
html[data-theme="dark"] .rule,
html[data-theme="dark"] .mini-rule{border-color:#7c836d}

.pending-link[aria-disabled="true"]{
  opacity:.48;
  cursor:not-allowed;
}
.pending-link[aria-disabled="true"]:hover{
  transform:none !important;
  background:transparent !important;
}


/* v12 — final QA: keyboard focus and reduced-motion support */
a:focus-visible,button:focus-visible{outline:2px solid var(--accent);outline-offset:4px}
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{scroll-behavior:auto!important;transition-duration:.01ms!important;animation-duration:.01ms!important;animation-iteration-count:1!important}
}