:root{
  --red:#DC0032;
  --red-dark:#A80026;
  --bg:#141414;
  --bg-1:#101010;
  --bg-elevated:#1D1D1D;
  --border:rgba(255,255,255,0.10);
  --border-soft:rgba(255,255,255,0.08);
  --text:#F5F5F7;
  --text-secondary:rgba(245,245,247,0.62);
  --text-tertiary:rgba(245,245,247,0.42);
  --ease:cubic-bezier(.16,.84,.44,1);
  --header-h:92px;
}
*{margin:0;padding:0;box-sizing:border-box;-webkit-tap-highlight-color:transparent;}
html{scroll-behavior:smooth;}
html::-webkit-scrollbar,body::-webkit-scrollbar{display:none;}
html,body{-ms-overflow-style:none;scrollbar-width:none;}
a{color:inherit;text-decoration:none;}
button{font-family:inherit;border:none;cursor:pointer;background:none;color:inherit;}
svg{display:block;}
a:focus-visible, button:focus-visible{outline:2px solid var(--red);outline-offset:2px;border-radius:8px;}

body{
  font-family:'Inter',-apple-system,BlinkMacSystemFont,"Helvetica Neue",Arial,sans-serif;
  font-weight:400;
  background:var(--bg);
  color:var(--text);
  -webkit-font-smoothing:antialiased;
  -moz-osx-font-smoothing:grayscale;
}

/* ---------- header (same treatment as landing page) ---------- */
header{
  position:fixed;top:0;left:0;right:0;z-index:200;
  height:var(--header-h);
  display:flex;align-items:center;
  background:transparent;
}
header::before{
  content:"";
  position:absolute;top:0;left:0;right:0;
  height:calc(var(--header-h) + 56px);
  z-index:-1;
  opacity:0;
  transition:opacity .4s var(--ease);
}
header.scrolled::before{
  opacity:1;
  background:rgba(14,14,14,0.68);
  backdrop-filter:blur(42px) saturate(180%);
  -webkit-backdrop-filter:blur(42px) saturate(180%);
  mask-image:linear-gradient(to bottom, black 0%, black 46%, rgba(0,0,0,0.5) 66%, rgba(0,0,0,0.18) 85%, transparent 100%);
  -webkit-mask-image:linear-gradient(to bottom, black 0%, black 46%, rgba(0,0,0,0.5) 66%, rgba(0,0,0,0.18) 85%, transparent 100%);
}
.header-inner{
  width:100%;max-width:1180px;margin:0 auto;padding:0 32px;
  display:flex;align-items:center;justify-content:space-between;
}
.tc-back{
  display:inline-flex;align-items:center;gap:9px;
  font-size:14.5px;font-weight:500;color:var(--text);
  transition:color .25s var(--ease);
}
.tc-back:hover,.tc-back:focus-visible,.tc-back:active{color:#b4b4b9;}
.tc-back svg{width:15px;height:15px;flex-shrink:0;}

.tc-tabs{display:flex;align-items:center;gap:8px;font-size:13.5px;font-weight:500;white-space:nowrap;}
.tc-tabs a{color:var(--text-secondary);padding:4px 2px;transition:color .25s var(--ease);}
.tc-tabs a:hover{color:var(--text);}
.tc-tabs .current{color:#fff;font-weight:600;}
.tc-tabs .sep{color:var(--text-tertiary);}
.tc-tabs .soon{color:var(--text-tertiary);cursor:default;}

/* ---------- layout ---------- */
main{display:block;}
.tc-hero{
  padding:calc(var(--header-h) + 64px) 32px 72px;
}
.tc-hero-inner{max-width:760px;margin:0 auto;text-align:center;}
.tc-shell{
  max-width:1180px;margin:0 auto;padding:72px 32px 140px;
  display:grid;grid-template-columns:216px minmax(0,700px);gap:72px;
  justify-content:center;
}

/* ---------- left TOC (sticky) ---------- */
.tc-toc{}
.tc-toc-sticky{position:sticky;top:calc(var(--header-h) + 32px);}
.tc-toc-track{
  position:relative;
  border-left:1px solid var(--border);padding-left:18px;
}
.tc-toc-indicator{
  position:absolute;left:-1px;top:0;
  width:1.5px;height:0;background:#fff;
  transform:translateY(0);
  transition:transform .45s var(--ease), height .45s var(--ease);
  will-change:transform,height;
}
.tc-toc-list{
  list-style:none;display:flex;flex-direction:column;gap:15px;
}
.tc-toc-list a{
  display:block;
  font-size:14px;font-weight:500;line-height:1.4;
  white-space:nowrap;
  color:var(--text-tertiary);
  transition:color .25s var(--ease);
}
.tc-toc-list a:hover{color:var(--text-secondary);}
.tc-toc-list a.active{color:#fff;}

/* ---------- content ---------- */
.tc-hero h1{
  font-family:'Inter',sans-serif;
  font-size:clamp(44px,7.5vw,84px);font-weight:600;
  letter-spacing:-0.03em;line-height:1.02;margin-bottom:24px;
}
.tc-lead{
  font-size:17px;font-weight:400;line-height:1.7;
  color:var(--text);max-width:640px;
}

.tc-section{
  padding-top:44px;margin-top:44px;
  border-top:1px solid var(--border-soft);
  scroll-margin-top:calc(var(--header-h) + 32px);
}
.tc-section:first-of-type{border-top:none;margin-top:0;padding-top:0;}
.tc-section h2{
  font-size:clamp(19px,2vw,21px);font-weight:600;
  letter-spacing:-0.01em;margin-bottom:20px;color:#fff;
}
.tc-section ul{list-style:none;display:flex;flex-direction:column;gap:15px;}
.tc-section li{
  position:relative;padding-left:22px;
  font-size:15.5px;font-weight:400;line-height:1.7;
  color:var(--text);
}
.tc-section li::before{
  content:"";position:absolute;left:0;top:10px;
  width:5px;height:5px;border-radius:50%;
  background:#fff;
}
.tc-section li strong{font-weight:600;color:var(--text);}

/* ---------- responsive ---------- */
@media (max-width:1000px){
  .tc-shell{grid-template-columns:1fr;gap:0;}
  .tc-toc{display:none;}
}
@media (max-width:640px){
  :root{--header-h:64px;}
  .header-inner{padding:0 18px;}
  .tc-back span{display:inline;}
  .tc-tabs{font-size:12px;gap:5px;}
  .tc-hero{padding:calc(var(--header-h) + 32px) 20px 40px;}
  .tc-hero h1{font-size:clamp(32px,11vw,40px);margin-bottom:14px;}
  .tc-lead{font-size:14.5px;}
  .lead-br{display:none;}
    .tc-shell{padding:40px 20px 100px;}
  .tc-section{padding-top:32px;margin-top:32px;}
  .tc-section h2{font-size:18px;margin-bottom:14px;}
  .tc-section li{font-size:14.5px;}
}