:root{
  --content:#FFFFFF;
  --sidebar:#E7F2F8;
  --ink:#0F172A;
  --link:#0369A1;
  --line:rgba(15,23,42,.14);
  --line-soft:rgba(15,23,42,.08);
  --muted:rgba(15,23,42,.66);
  --topbar-h:58px;
}

*,*::before,*::after{box-sizing:border-box}

html{scroll-behavior:smooth;scroll-padding-top:calc(var(--topbar-h) + 18px)}

body{
  margin:0;
  background:var(--content);
  color:var(--ink);
  font-family:"Source Sans 3",system-ui,sans-serif;
  font-size:17px;
  line-height:1.62;
  -webkit-font-smoothing:antialiased;
}

.mono{font-family:"IBM Plex Mono",ui-monospace,monospace}

a{color:var(--link);text-decoration:none}
a:hover{text-decoration:underline}

.skip{
  position:absolute;left:-9999px;top:0;background:var(--ink);color:#fff;
  padding:10px 16px;z-index:99;
}
.skip:focus{left:8px;top:8px}

/* ---------- top bar ---------- */
.topbar{
  position:sticky;top:0;z-index:40;
  background:var(--content);
  border-bottom:1px solid var(--line);
}
.topbar__inner{
  max-width:1180px;margin:0 auto;padding:0 22px;
  min-height:var(--topbar-h);
  display:flex;align-items:center;justify-content:space-between;gap:18px;flex-wrap:wrap;
}
.brand{display:flex;align-items:center;gap:9px;color:var(--ink);padding:9px 0}
.brand:hover{text-decoration:none}
.brand__mark{
  width:30px;height:30px;display:grid;place-items:center;
  border:1px solid var(--link);color:var(--link);background:var(--sidebar);
  border-radius:3px;flex:none;
}
.brand__text{font-weight:700;letter-spacing:-.015em;font-size:17px}
.brand__tag{
  font-family:"IBM Plex Mono",monospace;font-size:10.5px;letter-spacing:.14em;
  text-transform:uppercase;border:1px solid var(--line);border-radius:2px;
  padding:2px 6px;color:var(--muted);
}
.topbar__contact{
  margin:0;font-size:13.5px;color:var(--muted);
  display:flex;align-items:center;gap:8px;flex-wrap:wrap;padding:6px 0;
}
.topbar__contact .mono{font-size:11.5px;letter-spacing:.08em;text-transform:uppercase}
.topbar__sep{color:var(--line)}

/* ---------- shell ---------- */
.shell{
  max-width:1180px;margin:0 auto;padding:30px 22px 0;
  display:grid;grid-template-columns:238px minmax(0,1fr);gap:46px;align-items:start;
}

/* ---------- TOC ---------- */
.toc{
  position:sticky;top:calc(var(--topbar-h) + 22px);
  background:var(--sidebar);
  border:1px solid var(--line-soft);
  border-radius:4px;
  padding:18px 16px;
}
.toc__title{
  margin:0 0 10px;font-size:10.5px;letter-spacing:.16em;text-transform:uppercase;
  color:var(--muted);
}
.toc__title--pad{margin-top:22px}
.toc__list{list-style:none;margin:0;padding:0}
.toc__list li{margin:0}
.toc__list a{
  display:block;padding:6px 10px;border-left:2px solid transparent;
  color:var(--ink);font-size:15px;border-radius:0 3px 3px 0;
}
.toc__list a:hover{background:rgba(255,255,255,.75);text-decoration:none;color:var(--link)}
.toc__list a.is-active{
  border-left-color:var(--link);background:var(--content);
  color:var(--link);font-weight:600;
}
.toc__list--alt a{font-size:14.5px;color:var(--link)}
.toc__note{
  margin-top:22px;padding-top:14px;border-top:1px solid var(--line-soft);
  font-size:13px;color:var(--muted);display:grid;gap:4px;
}
.toc__note .mono{font-size:10.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--link)}

/* ---------- doc content ---------- */
.doc{min-width:0;padding-bottom:10px}
.sec{padding:0 0 46px;scroll-margin-top:calc(var(--topbar-h) + 20px)}
.sec + .sec{border-top:1px solid var(--line-soft);padding-top:38px}

.eyebrow{
  margin:0 0 12px;font-size:11px;letter-spacing:.16em;text-transform:uppercase;color:var(--link);
}

h1{
  font-size:clamp(28px,4.4vw,40px);line-height:1.16;letter-spacing:-.02em;
  margin:0 0 18px;font-weight:700;max-width:22ch;
}
h2{
  font-size:clamp(21px,2.6vw,26px);letter-spacing:-.015em;margin:0 0 12px;font-weight:700;
}
h3{font-size:17.5px;margin:0 0 8px;font-weight:600;letter-spacing:-.01em}

.lede{font-size:19px;color:var(--ink);margin:0 0 18px;max-width:66ch}
.sec__intro{color:var(--muted);max-width:68ch;margin:0 0 22px}
.sec__outro{margin:18px 0 0;color:var(--muted)}
p{max-width:70ch}

.callout{
  border:1px solid var(--line-soft);border-left:3px solid var(--link);
  background:var(--sidebar);padding:14px 16px;border-radius:0 4px 4px 0;margin:20px 0;
}
.callout p{margin:0;font-size:16px}
.callout--quiet{border-left-color:rgba(15,23,42,.3);background:rgba(231,242,248,.5)}

/* definition blocks */
.def{
  border:1px solid var(--line);border-radius:4px;
  padding:18px 18px 10px;margin:0 0 16px;background:var(--content);
  position:relative;
}
.def::before{
  content:"";position:absolute;left:-1px;top:16px;bottom:16px;width:3px;background:var(--link);
}
.def h3{padding-left:4px}
.def > p{margin:0 0 14px;padding-left:4px;color:var(--ink)}
.def__meta{
  margin:0;padding:12px 0 8px 4px;border-top:1px dashed var(--line);
  display:grid;gap:7px;
}
.def__meta > div{display:grid;grid-template-columns:118px minmax(0,1fr);gap:12px;align-items:baseline}
.def__meta dt{
  font-size:10.5px;letter-spacing:.1em;text-transform:uppercase;color:var(--link);
}
.def__meta dd{margin:0;font-size:15px;color:var(--muted)}

/* fact lists */
.facts{margin:22px 0 0;display:grid;gap:0;border-top:1px solid var(--line-soft)}
.facts > div{
  display:grid;grid-template-columns:150px minmax(0,1fr);gap:14px;
  padding:11px 2px;border-bottom:1px solid var(--line-soft);align-items:baseline;
}
.facts dt{font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--link)}
.facts dd{margin:0;font-size:16px}
.facts--wide > div{grid-template-columns:170px minmax(0,1fr)}

/* steps */
.steps{list-style:none;counter-reset:step;margin:0;padding:0}
.steps li{
  counter-increment:step;position:relative;padding:0 0 20px 46px;
  border-left:1px solid var(--line);margin-left:13px;
}
.steps li:last-child{border-left-color:transparent;padding-bottom:0}
.steps li::before{
  content:counter(step,decimal-leading-zero);
  position:absolute;left:-13px;top:0;width:26px;height:26px;
  display:grid;place-items:center;border-radius:50%;
  background:var(--sidebar);border:1px solid var(--link);color:var(--link);
  font-family:"IBM Plex Mono",monospace;font-size:10.5px;
}
.steps p{margin:0;color:var(--muted)}

/* faq */
.faq{border:1px solid var(--line);border-radius:4px;margin:0 0 10px;background:var(--content)}
.faq summary{
  cursor:pointer;list-style:none;padding:14px 46px 14px 16px;
  font-weight:600;position:relative;
}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{
  content:"";position:absolute;right:18px;top:50%;width:9px;height:9px;
  border-right:2px solid var(--link);border-bottom:2px solid var(--link);
  transform:translateY(-70%) rotate(45deg);transition:transform .18s ease;
}
.faq[open] summary::after{transform:translateY(-25%) rotate(-135deg)}
.faq[open] summary{background:var(--sidebar)}
.faq__body{padding:14px 16px 4px;border-top:1px solid var(--line-soft)}
.faq__body p{margin:0 0 12px;color:var(--muted)}

/* lists */
.list{margin:0 0 16px;padding-left:20px;max-width:70ch}
.list li{margin-bottom:9px}

/* ---------- form ---------- */
.form{
  margin:26px 0 0;border:1px solid var(--line);border-radius:4px;padding:20px;
  max-width:620px;background:var(--content);
}
.form__row{display:grid;gap:6px;margin-bottom:16px}
.form label{font-size:13px;letter-spacing:.03em;font-weight:600}
.form input,.form select,.form textarea{
  font-family:inherit;font-size:16px;color:var(--ink);
  border:1px solid var(--line);border-radius:3px;padding:10px 12px;
  background:var(--content);width:100%;
}
.form textarea{resize:vertical}
.form input:focus,.form select:focus,.form textarea:focus{
  outline:2px solid var(--link);outline-offset:1px;border-color:var(--link);
}
.form .invalid{border-color:var(--link);background:var(--sidebar)}
.check{display:flex;gap:10px;align-items:flex-start;font-weight:400;font-size:14.5px;margin-bottom:18px}
.check input{width:17px;height:17px;flex:none;margin-top:3px;accent-color:var(--link)}
.btn{
  font-family:inherit;font-size:15px;font-weight:600;cursor:pointer;
  background:var(--link);color:#fff;border:1px solid var(--link);
  border-radius:3px;padding:11px 22px;
}
.btn:hover{background:var(--ink);border-color:var(--ink)}
.form__status{margin:14px 0 0;font-size:14.5px;min-height:1.2em;color:var(--link)}

/* ---------- footer ---------- */
.foot{border-top:1px solid var(--line);padding:28px 0 48px;margin-top:10px}
.foot__grid{display:grid;grid-template-columns:1.6fr 1fr 1fr;gap:28px}
.foot__brand{font-weight:700;margin:0 0 6px}
.foot p{font-size:14.5px;color:var(--muted);margin:0}
.foot__label{font-size:10.5px!important;letter-spacing:.14em;text-transform:uppercase;color:var(--link)!important;margin-bottom:8px!important}
.foot__list{list-style:none;margin:0;padding:0;font-size:14.5px}
.foot__list li{margin-bottom:5px}
.foot__list--social a{display:inline-flex;align-items:center;gap:7px}
.foot__legal{
  margin-top:24px!important;padding-top:16px;border-top:1px solid var(--line-soft);
  font-size:12.5px!important;max-width:none;
}

/* ---------- responsive ---------- */
@media (max-width:900px){
  .shell{grid-template-columns:1fr;gap:24px;padding-top:18px}
  .toc{
    position:static;padding:14px;
  }
  .toc__title--pad{margin-top:16px}
  .toc__list{display:flex;gap:8px;overflow-x:auto;padding-bottom:4px;-webkit-overflow-scrolling:touch}
  .toc__list a{
    white-space:nowrap;border:1px solid var(--line);border-left-width:1px;
    background:var(--content);border-radius:999px;padding:6px 14px;font-size:14px;
  }
  .toc__list a.is-active{border-color:var(--link);border-left-width:1px}
  .toc__note{margin-top:14px}
  .foot__grid{grid-template-columns:1fr 1fr}
}

@media (max-width:560px){
  body{font-size:16.5px}
  .topbar__inner{padding:0 16px}
  .shell{padding-left:16px;padding-right:16px}
  .def__meta > div,.facts > div{grid-template-columns:1fr;gap:2px}
  .facts--wide > div{grid-template-columns:1fr}
  .foot__grid{grid-template-columns:1fr}
  .brand__text{font-size:16px}
}