:root{
  --ink:#080709; --slab:#120e15; --slab2:#170f1c; --edge:#2a1f33;
  --type:#efe9f3; --soft:#a99bb4; --mag:#db2777; --mag2:#f472b6; --amber:#fbbf24;
  --up:#4ade80; --down:#fb7185;
  --head:'Familjen Grotesk',system-ui,sans-serif;
  --read:'Inter Tight',system-ui,-apple-system,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--ink);color:var(--type);font-family:var(--read);line-height:1.66;
  -webkit-font-smoothing:antialiased;font-size:16.5px}
.bts-shell{max-width:1060px;margin:0 auto;padding:0 22px}
a{color:var(--mag2);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3{font-family:var(--head);line-height:1.14;letter-spacing:-.014em;font-weight:600}
h2{font-size:clamp(1.34rem,2.5vw,1.78rem);margin:0 0 .52em}
h3{font-size:1.08rem;margin:1.5em 0 .4em;color:#fff}
.bts-soft{color:var(--soft)}
section{padding:44px 0}
section + section{border-top:1px solid var(--edge)}
.bts-eyebrow{font-family:var(--head);font-size:.72rem;letter-spacing:.24em;text-transform:uppercase;
  color:var(--mag);margin-bottom:15px;font-weight:600}
/* top bar */
.bts-bar{position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;
  gap:18px;padding:13px 22px;background:rgba(8,7,9,.88);backdrop-filter:blur(10px);
  border-bottom:1px solid var(--edge)}
.bts-logo{display:flex;align-items:center;gap:10px;font-family:var(--head);font-weight:600;color:#fff;
  font-size:.98rem;letter-spacing:-.01em}
.bts-logo .dot{width:10px;height:10px;border-radius:50%;background:var(--mag);
  box-shadow:0 0 12px var(--mag)}
.bts-links{display:flex;gap:21px;list-style:none;margin:0;padding:0;font-size:.89rem}
.bts-links a{color:var(--soft)}
.bts-links a:hover{color:var(--type);text-decoration:none}
.bts-act{border:1px solid var(--mag);color:var(--mag2)!important;padding:7px 14px;border-radius:999px;
  font-size:.82rem;font-weight:500}
.bts-act:hover{background:rgba(219,39,119,.14);text-decoration:none}
.bts-burger{display:none;background:none;border:0;cursor:pointer;width:30px;height:24px}
.bts-burger span{display:block;height:2px;background:var(--type);margin:5px 0;border-radius:2px}
.bts-drawer{display:none;flex-direction:column;gap:2px;padding:8px 22px 18px;
  border-bottom:1px solid var(--edge);background:var(--slab)}
.bts-drawer a{color:var(--type);padding:10px 0;border-bottom:1px solid var(--edge);font-size:.96rem}
.bts-drawer.open{display:flex}
/* hero + content blocks */
.bts-top{padding:60px 0 42px}
.bts-flag{font-family:var(--head);font-size:.74rem;letter-spacing:.2em;text-transform:uppercase;
  color:var(--mag);font-weight:600}
.bts-top h1{font-size:clamp(2.05rem,4.5vw,3.05rem);margin:.32em 0 .28em;color:#fff;max-width:18ch}
.bts-stake{font-size:1.13rem;color:#d8cfe0;max-width:64ch}
.bts-pills{display:flex;flex-wrap:wrap;gap:10px;margin-top:25px;font-size:.84rem}
.bts-pill{border:1px solid var(--edge);background:var(--slab);border-radius:999px;padding:8px 14px;
  color:var(--soft)}
.bts-pill b{color:var(--mag2);font-weight:600}
.bts-go{display:inline-block;margin-top:27px;background:var(--mag);color:#fff;font-weight:600;
  padding:13px 22px;border-radius:999px;font-size:.94rem}
.bts-go:hover{background:#be1d63;text-decoration:none}
.bts-lead{font-size:1.07rem;color:#ddd4e4}
.bts-slab{background:var(--slab);border:1px solid var(--edge);border-radius:16px;padding:24px 26px;margin:18px 0}
.bts-slab.lit{border-color:#46264a;box-shadow:0 0 0 1px rgba(219,39,119,.12) inset}
.bts-grid{display:grid;gap:16px}
@media(min-width:720px){.bts-g3{grid-template-columns:repeat(3,1fr)}.bts-g2{grid-template-columns:1fr 1fr}}
.bts-card{background:var(--slab);border:1px solid var(--edge);border-radius:14px;padding:20px}
.bts-card h3{margin-top:0}
.bts-mark{font-family:var(--head);font-size:.7rem;letter-spacing:.16em;text-transform:uppercase;
  color:var(--mag);font-weight:600}
ul.bts-flags{list-style:none;padding:0;margin:15px 0}
ul.bts-flags li{padding:10px 0 10px 28px;position:relative;border-bottom:1px solid var(--edge);color:#d4cadd}
ul.bts-flags li:before{content:"\2715";position:absolute;left:6px;color:var(--mag);font-size:.82rem;top:11px}
ul.bts-checks{list-style:none;padding:0;margin:15px 0}
ul.bts-checks li{padding:10px 0 10px 28px;position:relative;border-bottom:1px solid var(--edge);color:#d4cadd}
ul.bts-checks li:before{content:"\2713";position:absolute;left:6px;color:var(--up);font-size:.92rem;top:10px}
.bts-scroll{overflow-x:auto;margin:18px 0}
table{border-collapse:collapse;width:100%;font-size:.9rem;min-width:520px}
th,td{padding:12px 14px;border-bottom:1px solid var(--edge);text-align:left}
th{font-family:var(--head);font-size:.72rem;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);font-weight:600}
td .bts-up{color:var(--up);font-weight:600}
tr.bts-star td{background:rgba(219,39,119,.06)}
.bts-trail{font-size:.78rem;color:var(--soft);padding:18px 0 0;font-family:var(--head);letter-spacing:.01em}
.bts-trail a{color:var(--soft)}
.bts-trail .bar{opacity:.5;margin:0 5px}
.bts-verdict{font-size:1.1rem;color:#d8cfe0;max-width:66ch;margin:.42em 0 0}
.bts-essay h3{color:var(--mag2)}
.bts-essay code{background:var(--slab2);border:1px solid var(--edge);border-radius:6px;padding:2px 7px;
  font-size:.84rem;color:var(--mag2);font-family:ui-monospace,SFMono-Regular,Menlo,monospace}
.bts-aside{font-size:.92rem;color:var(--soft);border-left:2px solid var(--mag);padding:6px 0 6px 16px;margin:18px 0}
.bts-foot{border-top:1px solid var(--edge);background:var(--slab2);margin-top:32px;padding:42px 0 30px}
.bts-foot .bts-cols{display:grid;gap:24px}
@media(min-width:720px){.bts-foot .bts-cols{grid-template-columns:2fr 1fr 1fr 1fr}}
.bts-foot a{color:var(--soft);display:block;padding:3px 0}
.bts-foot a:hover{color:var(--mag2)}
.bts-foot .bts-h{color:#fff;font-family:var(--head);font-size:.78rem;letter-spacing:.13em;
  text-transform:uppercase;margin-bottom:10px;font-weight:600}
.bts-fine{color:#7d6f88;font-size:.82rem;margin-top:26px;border-top:1px solid var(--edge);padding-top:18px}
td.bts-up,td .bts-up{color:var(--up)}
.bts-gradebar{color:var(--mag2)}
/* worked-example callout: a framed step block, magenta spine, distinct from .bts-aside */
.bts-worked{background:var(--slab2);border:1px solid var(--edge);border-left:3px solid var(--mag);
  border-radius:0 14px 14px 0;padding:20px 22px;margin:22px 0}
.bts-worked .bts-mark{margin-bottom:11px}
.bts-worked ol{margin:0;padding-left:21px}
.bts-worked ol li{padding:7px 0;color:#d4cadd}
.bts-worked ol li b{color:#fff}
/* on-brand inline diagram frame */
figure.bts-fig{margin:26px 0;background:var(--slab);border:1px solid var(--edge);border-radius:16px;
  padding:20px 18px 13px}
figure.bts-fig svg{display:block;width:100%;height:auto;max-width:760px;margin:0 auto}
figure.bts-fig figcaption{font-size:.78rem;color:var(--soft);text-align:center;margin-top:11px;
  font-family:var(--head);letter-spacing:.01em}
.bts-fig .f-box{fill:#170f1c;stroke:#46264a;stroke-width:1.2}
.bts-fig .f-cap{font-family:'Familjen Grotesk',system-ui,sans-serif;font-size:11.5px;fill:#fff;font-weight:600}
.bts-fig .f-sub{font-family:'Inter Tight',system-ui,sans-serif;font-size:9.5px;fill:#a99bb4}
.bts-fig .f-ax{font-family:'Inter Tight',system-ui,sans-serif;font-size:10px;fill:#a99bb4}
.bts-fig .f-yes{fill:#4ade80;font-family:'Familjen Grotesk',monospace;font-size:13px;font-weight:700}
.bts-fig .f-no{fill:#fb7185;font-family:'Familjen Grotesk',monospace;font-size:13px;font-weight:700}
.bts-fig .f-edge{stroke:var(--mag);stroke-width:1.6;fill:none}
/* 'Related' block at the foot of a leaf / hub page */
.bts-rel{margin:32px 0 0;border-top:1px solid var(--edge);padding-top:22px}
.bts-rel .bts-h{font-family:var(--head);font-size:.74rem;letter-spacing:.16em;text-transform:uppercase;
  color:var(--mag);margin-bottom:13px;font-weight:600}
.bts-rel .bts-cells{display:grid;gap:11px}
@media(min-width:620px){.bts-rel .bts-cells{grid-template-columns:1fr 1fr}}
.bts-rel a.bts-rc{display:block;border:1px solid var(--edge);border-radius:12px;padding:13px 15px;
  background:var(--slab);color:var(--type)}
.bts-rel a.bts-rc:hover{border-color:#46264a;text-decoration:none}
.bts-rel a.bts-rc b{color:var(--mag2);display:block;font-size:.95rem}
.bts-rel a.bts-rc span{color:var(--soft);font-size:.84rem}
@media(max-width:719px){.bts-links{display:none}.bts-burger{display:block}}

/* a11y + responsive polish */
:focus-visible{outline:2px solid currentColor;outline-offset:3px;border-radius:3px}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*{animation-duration:.01ms !important;transition-duration:.01ms !important}}
@media(max-width:719px){table{min-width:0}th,td{padding:8px 10px}}
/* mobile: stacked-card fallback for the .bts-scroll comparison tables */
@media(max-width:768px){
.bts-scroll{overflow-x:visible}
.bts-scroll table,.bts-scroll tbody,.bts-scroll tr,.bts-scroll td{display:block;width:auto}
.bts-scroll thead{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);clip-path:inset(50%);white-space:nowrap}
.bts-scroll tr{border:1px solid var(--edge);border-radius:10px;background:var(--slab2);margin:0 0 14px;padding:6px 14px}
.bts-scroll tr.bts-star{border-color:var(--mag);background:rgba(219,39,119,.06)}
.bts-scroll td{border-bottom:1px solid var(--edge);padding:9px 0;text-align:left}
.bts-scroll tr td:last-child{border-bottom:0}
.bts-scroll td::before{content:attr(data-label);display:block;font-family:var(--head);font-size:.64rem;letter-spacing:.1em;text-transform:uppercase;color:var(--soft);font-weight:600;margin:0 0 3px}
.bts-scroll td[data-label=""]::before{display:none}
}