:root{
  --ink:#08090c; --slab:#101218; --slab2:#15171f; --edge:#23262f;
  --fg:#e9ebef; --dim:#9aa0ac; --amber:#f59e0b; --amber2:#fbbf24; --rust:#b45309;
  --up:#4ade80; --down:#f87171;
  --code:'JetBrains Mono',ui-monospace,SFMono-Regular,Menlo,monospace;
  --head:'Chakra Petch',system-ui,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--ink);color:var(--fg);font-family:var(--code);line-height:1.66;
  -webkit-font-smoothing:antialiased;font-size:16px;letter-spacing:.002em}
.shell{max-width:1020px;margin:0 auto;padding:0 22px}
a{color:var(--amber2);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3{font-family:var(--head);line-height:1.14;letter-spacing:.01em;font-weight:600}
h2{font-size:clamp(1.32rem,2.5vw,1.74rem);margin:0 0 .5em;text-transform:uppercase}
h3{font-size:1.04rem;margin:1.5em 0 .35em;color:#fff}
.dim{color:var(--dim)}
section{padding:44px 0}
section + section{border-top:1px solid var(--edge)}
.eyebrow{font-family:var(--code);font-size:.7rem;letter-spacing:.26em;text-transform:uppercase;
  color:var(--amber);margin-bottom:13px}
/* chain-nav */
.bcs-bar{position:sticky;top:0;z-index:50;display:flex;align-items:center;justify-content:space-between;
  gap:16px;padding:12px 22px;background:rgba(8,9,12,.9);backdrop-filter:blur(10px);
  border-bottom:1px solid var(--edge)}
.bcs-sigil{display:flex;align-items:center;gap:9px;font-family:var(--head);font-weight:700;color:#fff;
  font-size:.96rem;letter-spacing:.02em;text-transform:uppercase}
.bcs-sigil .node{width:10px;height:10px;border-radius:50%;background:var(--amber);
  box-shadow:0 0 11px var(--amber)}
.bcs-links{display:flex;gap:21px;list-style:none;margin:0;padding:0;font-size:.85rem}
.bcs-links a{color:var(--dim)}
.bcs-links a:hover{color:var(--fg);text-decoration:none}
.bcs-go{border:1px solid var(--amber);color:var(--amber2)!important;padding:7px 14px;border-radius:6px;
  font-family:var(--code);font-size:.78rem;text-transform:uppercase;letter-spacing:.08em}
.bcs-go:hover{background:rgba(245,158,11,.12);text-decoration:none}
.bcs-burger{display:none;background:none;border:0;cursor:pointer;width:30px;height:24px}
.bcs-burger span{display:block;height:2px;background:var(--fg);margin:5px 0;border-radius:2px}
.bcs-drop{display:none;flex-direction:column;gap:3px;padding:8px 22px 18px;border-bottom:1px solid var(--edge);
  background:var(--slab)}
.bcs-drop a{color:var(--fg);padding:10px 0;border-bottom:1px solid var(--edge);font-size:.94rem}
.bcs-drop.open{display:flex}
/* hero + slabs */
.bcs-top{padding:60px 0 42px}
.brand-tag{font-family:var(--code);font-size:.72rem;letter-spacing:.22em;text-transform:uppercase;color:var(--amber)}
.bcs-top h1{font-size:clamp(2rem,4.5vw,3.05rem);margin:.3em 0 .26em;color:#fff;text-transform:none}
.thesis{font-size:1.1rem;color:#ccd0d8;max-width:63ch}
.readout{display:flex;flex-wrap:wrap;gap:9px;margin-top:25px;font-family:var(--code);font-size:.8rem}
.pill{border:1px solid var(--edge);background:var(--slab);border-radius:6px;padding:8px 12px;color:var(--dim)}
.pill b{color:var(--amber2);font-weight:600}
.cta{display:inline-block;margin-top:27px;background:var(--amber);color:#1b1203;font-weight:700;
  font-family:var(--code);padding:12px 21px;border-radius:7px;font-size:.9rem;text-transform:uppercase;
  letter-spacing:.05em}
.cta:hover{background:var(--amber2);text-decoration:none}
.lead{font-size:1.04rem;color:#d2d6dd}
.slab{background:var(--slab);border:1px solid var(--edge);border-radius:12px;padding:22px 24px;margin:18px 0}
.slab.anchor{border-color:#3a2f12;box-shadow:0 0 0 1px rgba(245,158,11,.1) inset}
.mesh{display:grid;gap:15px}
@media(min-width:720px){.m3{grid-template-columns:repeat(3,1fr)}.m2{grid-template-columns:1fr 1fr}}
.block{background:var(--slab);border:1px solid var(--edge);border-radius:10px;padding:18px}
.block h3{margin-top:0}
.stamp{font-family:var(--code);font-size:.68rem;letter-spacing:.16em;text-transform:uppercase;color:var(--amber)}
ul.marks{list-style:none;padding:0;margin:14px 0}
ul.marks li{padding:9px 0 9px 27px;position:relative;border-bottom:1px solid var(--edge);color:#cfd3da}
ul.marks li:before{content:"\25C8";position:absolute;left:6px;color:var(--amber);font-size:.7rem;top:12px}
.ledger{overflow-x:auto;margin:18px 0}
table{border-collapse:collapse;width:100%;font-size:.88rem;min-width:520px}
th,td{padding:11px 13px;border-bottom:1px solid var(--edge);text-align:left}
th{font-family:var(--code);font-size:.68rem;letter-spacing:.12em;text-transform:uppercase;color:var(--dim)}
td .gain{color:var(--up);font-family:var(--code)}
code{font-family:var(--code);font-size:.82em;background:var(--slab2);border:1px solid var(--edge);
  border-radius:4px;padding:1px 6px;color:var(--amber2);word-break:break-word}
.bcs-trail{font-family:var(--code);font-size:.74rem;color:var(--dim);padding:16px 0 0}
.bcs-trail a{color:var(--dim)}
.bcs-trail .div{opacity:.5;margin:0 5px}
.ruling{font-size:1.06rem;color:#ccd0d8;max-width:66ch;margin:.4em 0 0}
.prose h3{color:var(--amber2)}
.aside{font-family:var(--code);font-size:.82rem;color:var(--dim);border-left:2px solid var(--amber);
  padding:5px 0 5px 14px;margin:17px 0}
.bcs-base{border-top:1px solid var(--edge);background:var(--slab2);margin-top:32px;padding:42px 0 30px}
.bcs-base .grid{display:grid;gap:22px}
@media(min-width:720px){.bcs-base .grid{grid-template-columns:2fr 1fr 1fr 1fr}}
.bcs-base a{color:var(--dim);display:block;padding:3px 0}
.bcs-base a:hover{color:var(--amber2)}
.bcs-base .cap{color:#fff;font-family:var(--code);font-size:.74rem;letter-spacing:.13em;text-transform:uppercase;margin-bottom:10px}
.fine{color:#6c727d;font-size:.8rem;margin-top:25px;border-top:1px solid var(--edge);padding-top:16px}
/* receipt block: a framed, monospace step sequence for the worked walkthrough */
.receipt{background:var(--slab2);border:1px solid var(--edge);border-left:3px solid var(--amber);
  border-radius:0 10px 10px 0;padding:18px 20px;margin:20px 0}
.receipt .stamp{margin-bottom:11px}
.receipt ol{margin:0;padding-left:21px;counter-reset:step}
.receipt ol li{padding:7px 0;color:#cfd3da}
.receipt ol li b{color:#fff}
/* on-brand inline diagram frame (amber on dark; titled + a11y) */
figure.schema-fig{margin:24px 0;background:var(--slab);border:1px solid var(--edge);border-radius:12px;
  padding:18px 18px 12px}
figure.schema-fig svg{display:block;width:100%;height:auto;max-width:760px;margin:0 auto}
figure.schema-fig figcaption{font-family:var(--code);font-size:.78rem;color:var(--dim);
  text-align:center;margin-top:11px}
.schema-fig .n-box{fill:var(--slab2,#15171f);stroke:#3a2f12;stroke-width:1.2}
.schema-fig .n-link{stroke:var(--amber);stroke-width:1.6;fill:none}
.schema-fig .n-cap{font-family:'JetBrains Mono',monospace;font-size:11.5px;fill:#fff;font-weight:600}
.schema-fig .n-sub{font-family:'JetBrains Mono',monospace;font-size:9.5px;fill:#9aa0ac}
.schema-fig .n-axis{font-family:'JetBrains Mono',monospace;font-size:10px;fill:#9aa0ac}
.schema-fig .n-yes{fill:#4ade80;font-family:'JetBrains Mono',monospace;font-size:13px;font-weight:700}
.schema-fig .n-no{fill:#f87171;font-family:'JetBrains Mono',monospace;font-size:13px;font-weight:700}
/* sibling 'Read next' block at a leaf or hub foot */
.next-up{margin:30px 0 0;border-top:1px solid var(--edge);padding-top:20px}
.next-up .cap{font-family:var(--code);font-size:.72rem;letter-spacing:.18em;text-transform:uppercase;
  color:var(--amber);margin-bottom:12px}
.next-up .pair{display:grid;gap:10px}
@media(min-width:620px){.next-up .pair{grid-template-columns:1fr 1fr}}
.next-up a.tile{display:block;border:1px solid var(--edge);border-radius:9px;padding:12px 14px;
  background:var(--slab);color:var(--fg)}
.next-up a.tile:hover{border-color:#3a2f12;text-decoration:none}
.next-up a.tile b{color:var(--amber2);display:block;font-size:.93rem}
.next-up a.tile span{color:var(--dim);font-size:.83rem}
.barline{font-family:var(--code);color:var(--amber2)}
@media(max-width:719px){.bcs-links{display:none}.bcs-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){th,td{padding:8px 10px}}
/* <=768px: data tables restack into labelled cards instead of a cramped squeeze */
@media(max-width:768px){
  .ledger{overflow-x:visible}
  .ledger table{min-width:0;border-collapse:separate;border-spacing:0}
  .ledger thead{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
  .ledger tbody{display:block}
  .ledger tr{display:block;background:var(--slab);border:1px solid var(--edge);border-radius:10px;padding:6px 14px;margin:0 0 12px}
  .ledger tr[style*="background"]{border-color:#3a2f12;box-shadow:0 0 0 1px rgba(245,158,11,.12) inset}
  .ledger td{display:block;border-bottom:1px solid var(--edge);padding:9px 0;text-align:left}
  .ledger tr td:last-child{border-bottom:0}
  .ledger td::before{content:attr(data-label);display:block;font-family:var(--code);font-size:.64rem;
    letter-spacing:.12em;text-transform:uppercase;color:var(--dim);margin-bottom:3px}
}