/* ============================================================
   TRESONANT.AI — tresonant.co
   Paper-white, severe, engineered.
   ============================================================ */

:root{
  --paper:#FAFAF7;
  --paper-raised:#FFFFFF;
  --ink:#0E1116;
  --ink-2:#3D434D;
  --ink-3:#6B7280;
  --hairline:#E3E2DC;
  --hairline-strong:#C9C8C0;
  --accent:#0F62FE;
  --accent-ink:#0043CE;
  --accent-wash:#EDF3FF;
  --ok:#1F7A4D;
  --warn:#B54708;
  --inverse-bg:#0E1116;
  --inverse-ink:#F4F4F1;
  --inverse-hairline:#262B33;

  --font-display:"Instrument Sans",system-ui,sans-serif;
  --font-body:"Inter",system-ui,sans-serif;
  --font-mono:"IBM Plex Mono",ui-monospace,SFMono-Regular,Menlo,monospace;

  --fs-display:clamp(2.75rem,2rem + 4vw,5.25rem);
  --fs-h2:clamp(1.9rem,1.4rem + 1.8vw,3rem);
  --fs-h3:clamp(1.25rem,1.1rem + 0.6vw,1.6rem);
  --fs-body:clamp(1rem,0.95rem + 0.2vw,1.125rem);
  --fs-small:0.875rem;
  --fs-mono-label:0.75rem;

  --space-section:clamp(88px,12vh,144px);
  --header-h:64px;
}

*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}

html{scroll-behavior:smooth;scroll-padding-top:calc(var(--header-h) + 24px)}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}}

body{
  font-family:var(--font-body);
  font-size:var(--fs-body);
  line-height:1.65;
  color:var(--ink);
  background:var(--paper);
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}

::selection{background:var(--accent);color:#fff}

img,svg{max-width:100%;height:auto}
svg{display:block}

a{color:var(--accent);text-decoration:none;transition:color 120ms ease-out}
a:hover{color:var(--accent-ink)}

:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

h1,h2,h3,h4{font-family:var(--font-display);font-weight:600;color:var(--ink)}
h1{font-size:var(--fs-display);letter-spacing:-0.03em;line-height:1.02}
h2{font-size:var(--fs-h2);letter-spacing:-0.02em;line-height:1.1}
h3{font-size:var(--fs-h3);letter-spacing:-0.01em;line-height:1.25}

p{max-width:65ch}

.num,.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}

.container{max-width:1200px;margin-inline:auto;padding-inline:clamp(20px,4vw,48px)}
.measure{max-width:760px}

/* ---------- skip link ---------- */
.skip-link{
  position:absolute;left:-9999px;top:0;z-index:200;
  background:var(--ink);color:var(--paper);
  padding:10px 16px;font-size:var(--fs-small);font-weight:500;border-radius:0 0 6px 0;
}
.skip-link:focus{left:0;color:var(--paper)}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:100;height:var(--header-h);
  background:rgba(250,250,247,0.82);
  -webkit-backdrop-filter:blur(12px) saturate(1.2);
  backdrop-filter:blur(12px) saturate(1.2);
  border-bottom:1px solid transparent;
  transition:border-color 120ms ease-out;
}
.site-header.is-scrolled{border-bottom-color:var(--hairline)}

.header-inner{display:flex;align-items:center;gap:32px;height:var(--header-h)}

.lockup{display:inline-flex;align-items:center;gap:10px;color:var(--ink)}
.lockup:hover{color:var(--ink)}
.lockup .mark{flex:none}
.wordmark{
  font-family:var(--font-display);font-weight:600;font-size:1.0625rem;
  letter-spacing:0.02em;color:var(--ink);line-height:1;
}
.wordmark-ai{
  font-family:var(--font-mono);font-weight:500;font-size:0.72em;
  color:var(--ink-3);letter-spacing:0.02em;
  transition:color 120ms ease-out;
}
.lockup:hover .wordmark-ai{color:var(--accent)}

.site-nav{display:flex;align-items:center;gap:28px;margin-left:auto}
.site-nav ul{display:flex;align-items:center;gap:24px;list-style:none}
.site-nav ul a{
  font-size:0.9375rem;font-weight:500;color:var(--ink-2);
  transition:color 120ms ease-out;
}
.site-nav ul a:hover{color:var(--ink)}
.site-nav ul a[aria-current="page"]{color:var(--ink);box-shadow:0 1px 0 0 var(--ink)}

.nav-toggle{display:none}

/* ---------- buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  height:44px;padding:0 20px;border-radius:6px;
  font-family:var(--font-body);font-size:0.9375rem;font-weight:500;line-height:1;
  border:1px solid transparent;cursor:pointer;white-space:nowrap;
  transition:background-color 140ms ease-out,border-color 140ms ease-out,color 140ms ease-out;
}
.btn-primary{background:var(--ink);color:var(--paper)}
.btn-primary:hover{background:#1A1F27;color:var(--paper)}
.btn-secondary{background:transparent;border-color:var(--hairline-strong);color:var(--ink)}
.btn-secondary:hover{border-color:var(--ink);color:var(--ink)}
.inverse .btn-primary,.site-footer .btn-primary{background:var(--accent);color:#fff}
.inverse .btn-primary:hover,.site-footer .btn-primary:hover{background:var(--accent-ink);color:#fff}
.inverse .btn-secondary{border-color:var(--inverse-hairline);color:var(--inverse-ink)}
.inverse .btn-secondary:hover{border-color:var(--inverse-ink)}

/* ---------- section scaffolding ---------- */
.section{padding-block:var(--space-section)}
.section-head{margin-bottom:clamp(40px,6vh,64px)}
.eyebrow{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
  display:block;margin-bottom:12px;
}
.eyebrow .accent{color:var(--accent)}
.rule{border:none;border-top:1px solid var(--hairline);margin:0 0 28px}
.section-head h2{max-width:22ch}
.section-lede{margin-top:20px;color:var(--ink-2);max-width:60ch}

/* ---------- hero ---------- */
.hero{padding-top:clamp(96px,14vh,160px);padding-bottom:var(--space-section)}
.hero-grid{display:grid;grid-template-columns:55fr 45fr;gap:clamp(32px,5vw,72px);align-items:center}
.hero-copy .eyebrow{margin-bottom:10px}
.hero-copy .rule{margin-bottom:32px}
.hero h1{max-width:14ch}
.hero h1 .accent{color:var(--accent)}
.hero-sub{margin-top:24px;font-size:1.125rem;color:var(--ink-2);max-width:52ch}
.hero-ctas{display:flex;flex-wrap:wrap;gap:12px;margin-top:36px}
.hero-proof{
  margin-top:28px;font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.04em;color:var(--ink-3);line-height:1.9;
}

/* ---------- figures ---------- */
.figure{border:1px dashed var(--hairline-strong);padding:clamp(16px,3vw,32px);background:transparent}
.figure svg{width:100%;height:auto}
.figcaption{
  margin-top:14px;font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
}
.figure-wide{margin-top:8px;overflow-x:auto}
.figure-wide svg{min-width:640px}

.sig-active{stroke:var(--accent)}
@media (prefers-reduced-motion:no-preference){
  .sig-animate{stroke-dasharray:6 6;animation:sigflow 4s linear infinite}
  @keyframes sigflow{to{stroke-dashoffset:-48}}
}

/* ---------- principles strip ---------- */
.strip{border-top:1px solid var(--hairline);border-bottom:1px solid var(--hairline);padding-block:20px}
.strip-items{
  display:flex;flex-wrap:wrap;gap:12px 40px;justify-content:space-between;
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
}
.strip-items span::before{content:"■ ";color:var(--hairline-strong);font-size:0.6em;vertical-align:2px}

/* ---------- cards ---------- */
.card-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.card{
  background:var(--paper-raised);border:1px solid var(--hairline);border-radius:8px;
  padding:32px;display:flex;flex-direction:column;
  transition:border-color 180ms ease-out,transform 180ms ease-out,box-shadow 180ms ease-out;
}
.card:hover{
  border-color:var(--hairline-strong);transform:translateY(-2px);
  box-shadow:0 12px 32px rgba(14,17,22,0.06);
}
.card-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px}
.card-index{font-family:var(--font-mono);font-size:var(--fs-mono-label);font-weight:500;letter-spacing:0.08em;color:var(--ink-3)}
.card-icon{color:var(--ink)}
.card h3{margin-bottom:12px}
.card p{font-size:0.9375rem;color:var(--ink-2);flex:1}
.card-link{
  margin-top:24px;font-size:0.9375rem;font-weight:500;color:var(--ink);
  display:inline-flex;align-items:center;gap:6px;
}
.card-link:hover{color:var(--accent-ink)}

/* ---------- lists ---------- */
.speclist{list-style:none;max-width:65ch}
.speclist li{
  padding:14px 0 14px 28px;border-bottom:1px solid var(--hairline);
  position:relative;color:var(--ink-2);font-size:0.9375rem;
}
.speclist li::before{
  content:"";position:absolute;left:4px;top:1.45em;
  width:6px;height:6px;background:var(--accent);
}
.speclist li strong{color:var(--ink);font-weight:600}

/* ---------- inverse (dark) bands ---------- */
.inverse{background:var(--inverse-bg);color:var(--inverse-ink)}
.inverse h2,.inverse h3{color:var(--inverse-ink)}
.inverse .eyebrow{color:#9CA3AF}
.inverse .rule{border-top-color:var(--inverse-hairline)}
.inverse p{color:#B9BEC6}

.metric-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border-left:1px solid var(--inverse-hairline)}
.metric{padding:8px 28px;border-right:1px solid var(--inverse-hairline)}
.metric .metric-num{
  font-family:var(--font-mono);font-weight:500;font-variant-numeric:tabular-nums;
  font-size:clamp(1.8rem,1.4rem + 1.4vw,2.6rem);color:var(--inverse-ink);line-height:1.1;
}
.metric .metric-num .accent{color:var(--accent)}
.metric .metric-label{
  margin-top:10px;font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:#9CA3AF;line-height:1.7;
}
.metric-note{margin-top:32px;font-family:var(--font-mono);font-size:var(--fs-mono-label);letter-spacing:0.04em;color:#6B7280}

/* ---------- spec tables ---------- */
.spec-table{width:100%;border-collapse:collapse}
.spec-table th{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
  text-align:left;padding:12px 16px 12px 0;border-bottom:1px solid var(--hairline-strong);
}
.spec-table td{
  font-size:0.9375rem;color:var(--ink-2);padding:14px 16px 14px 0;
  border-bottom:1px solid var(--hairline);vertical-align:top;
}
.spec-table td:first-child{color:var(--ink);font-weight:500}
.spec-table .num-cell{text-align:right;font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.spec-table .ok{color:var(--ok);font-family:var(--font-mono)}
.spec-table .na{color:var(--ink-3);font-family:var(--font-mono)}
.table-scroll{overflow-x:auto}
.table-scroll table{min-width:640px}

/* ---------- pull quote ---------- */
.pull{border-top:1px solid var(--hairline);border-bottom:1px solid var(--hairline);padding-block:clamp(48px,7vh,72px)}
.pull blockquote p{
  font-family:var(--font-display);font-weight:500;
  font-size:clamp(1.4rem,1.1rem + 1.2vw,2rem);letter-spacing:-0.015em;line-height:1.3;
  color:var(--ink);max-width:30ch;
}
.pull figcaption{
  margin-top:24px;font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
}

/* ---------- FAQ ---------- */
.faq{max-width:760px}
.faq details{border-bottom:1px solid var(--hairline)}
.faq details:first-of-type{border-top:1px solid var(--hairline)}
.faq summary{
  list-style:none;cursor:pointer;padding:20px 0;
  display:flex;align-items:center;justify-content:space-between;gap:24px;
  font-weight:500;font-size:1.0625rem;color:var(--ink);
}
.faq summary::-webkit-details-marker{display:none}
.faq summary .indicator{flex:none;color:var(--ink);transition:transform 160ms ease-out}
.faq details[open] summary .indicator{transform:rotate(45deg)}
.faq .answer{padding:0 0 24px;color:var(--ink-2);max-width:65ch;font-size:0.9375rem}
.faq .answer p + p{margin-top:12px}

/* ---------- CTA band ---------- */
.cta-band{text-align:left}
.cta-band .btn-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:36px}
.cta-band .cta-note{margin-top:20px;font-family:var(--font-mono);font-size:var(--fs-mono-label);letter-spacing:0.04em;color:var(--ink-3)}
.inverse .cta-band .cta-note{color:#6B7280}

/* ---------- footer ---------- */
.site-footer{background:var(--inverse-bg);color:var(--inverse-ink);padding-top:clamp(64px,8vh,96px)}
.footer-top{
  display:flex;flex-wrap:wrap;gap:32px;justify-content:space-between;align-items:flex-start;
  padding-bottom:48px;border-bottom:1px solid var(--inverse-hairline);
}
.footer-brand{max-width:340px}
.footer-brand .lockup{color:var(--inverse-ink)}
.footer-brand .wordmark{color:var(--inverse-ink)}
.footer-brand .desc{margin-top:16px;font-size:var(--fs-small);color:#9CA3AF}
.footer-plaque{
  margin-top:20px;font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:#6B7280;
}
.footer-cols{display:grid;grid-template-columns:repeat(4,minmax(120px,1fr));gap:32px}
.footer-cols h2{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:#6B7280;margin-bottom:16px;
}
.footer-cols ul{list-style:none}
.footer-cols li{margin-bottom:10px}
.footer-cols a{font-size:var(--fs-small);font-weight:400;color:#9CA3AF;transition:color 120ms ease-out}
.footer-cols a:hover{color:#fff}
.footer-legal{
  padding-block:28px;font-size:0.8125rem;color:#9CA3AF;
  display:flex;flex-direction:column;gap:8px;
}
.footer-legal p{max-width:none;color:#9CA3AF}
.footer-legal a{color:#9CA3AF;text-decoration:underline;text-underline-offset:2px}
.footer-legal a:hover{color:#fff}
.footer-bottom{
  border-top:1px solid var(--inverse-hairline);padding-block:20px 28px;
  display:flex;flex-wrap:wrap;gap:12px 32px;align-items:center;justify-content:space-between;
}
.footer-bottom .legal-links{display:flex;flex-wrap:wrap;gap:20px;list-style:none}
.footer-bottom .legal-links a{font-size:0.8125rem;color:#9CA3AF}
.footer-bottom .legal-links a:hover{color:#fff}
.footer-status{
  display:inline-flex;align-items:center;gap:10px;
  font-family:var(--font-mono);font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:#9CA3AF;
}
.footer-status::before{content:"";width:6px;height:6px;background:var(--ok);flex:none}

/* ---------- page hero (interior pages) ---------- */
.page-hero{padding-top:clamp(72px,10vh,120px);padding-bottom:clamp(48px,7vh,80px)}
.page-hero h1{font-size:clamp(2.4rem,1.8rem + 2.6vw,4rem);max-width:18ch}
.page-hero h1 .accent{color:var(--accent)}
.page-hero .hero-sub{margin-top:20px}

/* ---------- two-column detail rows ---------- */
.detail-row{
  display:grid;grid-template-columns:minmax(0,5fr) minmax(0,7fr);gap:clamp(32px,5vw,72px);
  padding-block:clamp(48px,7vh,72px);border-top:1px solid var(--hairline);
}
.detail-row:last-of-type{border-bottom:1px solid var(--hairline)}
.detail-row h3{max-width:20ch}
.detail-row .detail-kicker{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);
  display:block;margin-bottom:12px;
}
.detail-row .detail-body p{color:var(--ink-2);font-size:0.9375rem}
.detail-row .detail-body p + p{margin-top:14px}
.detail-row .speclist{margin-top:20px}
.detail-row .speclist li:first-child{border-top:1px solid var(--hairline)}

.scenario{
  border:1px solid var(--hairline);border-left:2px solid var(--accent);
  background:var(--paper-raised);border-radius:0 8px 8px 0;
  padding:24px 28px;margin-top:24px;
}
.scenario .scenario-label{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--accent);
  display:block;margin-bottom:10px;
}
.scenario p{font-size:0.9375rem;color:var(--ink-2)}

/* ---------- fact table (about/contact) ---------- */
.fact-list{border-top:1px solid var(--hairline);max-width:760px}
.fact-list div{
  display:grid;grid-template-columns:minmax(140px,220px) 1fr;gap:16px;
  padding:14px 0;border-bottom:1px solid var(--hairline);
}
.fact-list dt{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);padding-top:3px;
}
.fact-list dd{font-size:0.9375rem;color:var(--ink-2)}
.fact-list dd .num{font-family:var(--font-mono)}

/* ---------- legal pages ---------- */
.legal-layout{display:grid;grid-template-columns:260px minmax(0,1fr);gap:clamp(32px,5vw,72px);align-items:start}
.legal-toc{
  position:sticky;top:calc(var(--header-h) + 24px);
  border:1px solid var(--hairline);border-radius:8px;background:var(--paper-raised);
  padding:20px;max-height:calc(100vh - var(--header-h) - 48px);overflow-y:auto;
}
.legal-toc h2{
  font-family:var(--font-mono);font-weight:500;font-size:var(--fs-mono-label);
  letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3);margin-bottom:12px;
}
.legal-toc ol{list-style:none;counter-reset:toc}
.legal-toc li{margin-bottom:6px}
.legal-toc a{
  font-size:0.8125rem;color:var(--ink-2);display:flex;gap:8px;line-height:1.45;
}
.legal-toc a:hover{color:var(--accent-ink)}
.legal-toc a .toc-num{font-family:var(--font-mono);color:var(--ink-3);flex:none}
.legal-body{max-width:760px}
.legal-meta{
  font-family:var(--font-mono);font-size:var(--fs-mono-label);letter-spacing:0.06em;
  text-transform:uppercase;color:var(--ink-3);margin-top:16px;
}
.legal-body section{padding-top:40px}
.legal-body section h2{
  font-size:1.35rem;letter-spacing:-0.01em;
  padding-bottom:12px;border-bottom:1px solid var(--hairline);margin-bottom:20px;
}
.legal-body section h2 .sec-num{font-family:var(--font-mono);font-weight:500;font-size:0.8em;color:var(--ink-3);margin-right:12px}
.legal-body h3{font-size:1.05rem;margin:24px 0 10px}
.legal-body p{font-size:0.9375rem;color:var(--ink-2);margin-bottom:14px}
.legal-body ul,.legal-body ol{margin:0 0 14px 22px;font-size:0.9375rem;color:var(--ink-2)}
.legal-body li{margin-bottom:8px;max-width:62ch}
.legal-body li::marker{color:var(--ink-3)}
.legal-body strong{color:var(--ink)}
.legal-body .spec-table td:first-child{font-weight:400;color:var(--ink-2)}
.legal-body .spec-table td strong{font-weight:500}
.backtop{margin-top:48px}
.backtop a{font-family:var(--font-mono);font-size:var(--fs-mono-label);letter-spacing:0.08em;text-transform:uppercase;color:var(--ink-3)}
.backtop a:hover{color:var(--accent-ink)}

/* ---------- reveal ---------- */
.js .reveal{opacity:0;transform:translateY(8px);transition:opacity 400ms ease-out,transform 400ms ease-out}
.js .reveal.in{opacity:1;transform:none}
@media (prefers-reduced-motion:reduce){
  .js .reveal{opacity:1;transform:none;transition:none}
  *,*::before,*::after{animation-duration:0.01ms !important;animation-iteration-count:1 !important;transition-duration:0.01ms !important}
}

/* ---------- responsive ---------- */
@media (max-width:1080px){
  .metric-grid{grid-template-columns:repeat(2,1fr);border-top:1px solid var(--inverse-hairline)}
  .metric{padding:24px 28px;border-bottom:1px solid var(--inverse-hairline)}
}

@media (max-width:900px){
  .hero-grid{grid-template-columns:1fr}
  .hero-visual{max-width:560px}
  .card-grid{grid-template-columns:1fr;max-width:560px}
  .detail-row{grid-template-columns:1fr;gap:24px}
  .legal-layout{grid-template-columns:1fr}
  .legal-toc{position:static;max-height:none}
  .footer-cols{grid-template-columns:repeat(2,1fr)}

  .nav-toggle{
    display:inline-flex;align-items:center;justify-content:center;
    width:44px;height:44px;margin-left:auto;
    background:transparent;border:1px solid transparent;border-radius:6px;
    color:var(--ink);cursor:pointer;
  }
  .nav-toggle:hover{border-color:var(--hairline-strong)}
  .nav-toggle .icon-close{display:none}
  .nav-toggle[aria-expanded="true"] .icon-open{display:none}
  .nav-toggle[aria-expanded="true"] .icon-close{display:block}

  .site-nav{
    position:fixed;inset:var(--header-h) 0 0 0;z-index:99;
    display:none;flex-direction:column;align-items:stretch;gap:0;
    background:var(--paper);border-top:1px solid var(--hairline);
    padding:24px clamp(20px,4vw,48px) 40px;overflow-y:auto;margin-left:0;
  }
  .site-nav.is-open{display:flex}
  .site-nav ul{flex-direction:column;align-items:stretch;gap:0}
  .site-nav ul a{
    display:block;padding:18px 0;font-size:1.25rem;font-weight:500;
    font-family:var(--font-display);border-bottom:1px solid var(--hairline);
  }
  .site-nav ul a[aria-current="page"]{box-shadow:none;color:var(--accent)}
  .site-nav .nav-cta{margin-top:28px;width:100%}
  body.nav-locked{overflow:hidden}
}

@media (max-width:520px){
  .footer-cols{grid-template-columns:1fr;gap:24px}
  .metric-grid{grid-template-columns:1fr}
  .strip-items{flex-direction:column;gap:10px}
  .fact-list div{grid-template-columns:1fr;gap:4px;padding:12px 0}
}