/* ArbLedger — "the gap between two prices".
   Layout concept: a trading terminal at night. Deep navy ground with a fine grid, all in blues: brand blue = side A,
   light blue = side B, sky blue = locked profit. Red only for errors and losses, amber only for draft/warnings.
   Display: Inter Tight (neutral by request). Body: Instrument Sans. Numbers: JetBrains Mono. Single deliberate dark theme. */
:root{
  color-scheme:dark;
  --bg:#070B14;
  --bg-2:#0A1020;
  --surface:#0E1628;
  --surface-2:#131E36;
  --surface-3:#192643;
  --line:#22304F;
  --line-soft:#18233D;
  --fg:#ECF1FF;
  --fg-mid:#A3B1CF;
  --fg-lo:#7584A6;
  --side-a:#4D7CFF;
  --side-a-soft:rgba(77,124,255,.14);
  --side-b:#9DB9FF;
  --side-b-soft:rgba(157,185,255,.14);
  --profit:#5CC8FF;
  --bad:#FF6B81;
  --bad-soft:rgba(255,107,129,.12);
  --profit-soft:rgba(92,200,255,.12);
  --warn:#FFC24B;
  --warn-soft:rgba(255,194,75,.12);
  --gap:linear-gradient(90deg,#3D6BFF,#6E9BFF);
  --btn:#3A63F0;
  --btn-hover:#4469F2;
  --r:14px;
  --r-sm:10px;
  --f-display:'Inter Tight', 'Segoe UI', system-ui, sans-serif;
  --f-body:'Instrument Sans', 'Segoe UI', system-ui, sans-serif;
  --f-mono:'JetBrains Mono', ui-monospace, Consolas, monospace;
}
*{box-sizing:border-box}
[hidden]{display:none!important}
html{scroll-padding-top:84px;background:var(--bg)}
body{
  margin:0;
  background:
    radial-gradient(900px 520px at 88% -120px, rgba(157,185,255,.13), transparent 70%),
    radial-gradient(900px 560px at -10% -80px, rgba(77,124,255,.16), transparent 70%),
    var(--bg);
  color:var(--fg);
  font-family:var(--f-body);
  font-size:16px;
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
  min-height:100vh;
}
body::before{ /* fine terminal grid */
  content:"";position:fixed;inset:0;pointer-events:none;z-index:-1;
  background-image:
    linear-gradient(rgba(120,150,220,.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(120,150,220,.06) 1px, transparent 1px);
  background-size:44px 44px;
  mask-image:linear-gradient(180deg, rgba(0,0,0,.9), rgba(0,0,0,.25) 60%, transparent);
  -webkit-mask-image:linear-gradient(180deg, rgba(0,0,0,.9), rgba(0,0,0,.25) 60%, transparent);
}
a{color:#8FB0FF}
a:hover{color:#B7CCFF}
::selection{background:rgba(77,124,255,.4)}
:focus-visible{outline:2px solid var(--side-a);outline-offset:2px;border-radius:4px}

.skip{position:absolute;left:-999px;top:8px;background:var(--btn);color:#fff;padding:8px 14px;z-index:50;text-decoration:none;border-radius:8px}
.skip:focus{left:12px}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.gap-text{background:var(--gap);-webkit-background-clip:text;background-clip:text;color:transparent}
.mono{font-family:var(--f-mono)}

/* ---------- header ---------- */
.site-header{
  position:sticky;top:0;z-index:40;
  background:rgba(7,11,20,.72);
  backdrop-filter:saturate(160%) blur(14px);-webkit-backdrop-filter:saturate(160%) blur(14px);
  border-bottom:1px solid var(--line-soft);
}
.site-header .in{max-width:1180px;margin:0 auto;padding-block:12px;padding-inline:16px;display:flex;align-items:center;gap:18px}
.brand{display:inline-flex;align-items:center;gap:10px;text-decoration:none;color:var(--fg);flex:none}
.brand svg{width:30px;height:30px;flex:none}
.brand .wm{font-family:var(--f-display);font-weight:800;font-size:21px;letter-spacing:-.02em;line-height:1}
.brand .wm b{font-weight:800;color:var(--side-a)}
.site-nav{display:flex;gap:2px;overflow-x:auto;scrollbar-width:none;margin-left:auto;min-width:0}
.site-nav::-webkit-scrollbar{display:none}
.site-nav a{
  font-size:14px;font-weight:600;color:var(--fg-mid);text-decoration:none;
  padding:8px 12px;border-radius:999px;white-space:nowrap;
}
.site-nav a:hover{color:var(--fg);background:var(--surface-2)}
.site-nav a[aria-current="page"]{color:var(--fg);background:var(--surface-3);box-shadow:inset 0 0 0 1px var(--line)}
.nav-cta{flex:none;font-size:14px;font-weight:700;text-decoration:none;color:#fff;padding:9px 16px;border-radius:999px;background:var(--btn);box-shadow:0 6px 22px -8px rgba(61,107,255,.55)}
.nav-cta:hover{color:#fff;background:var(--btn-hover)}
@media (max-width:760px){
  .site-header .in{flex-wrap:wrap;row-gap:8px}
  .nav-cta{margin-left:auto}
  .site-nav{order:3;margin-left:0;width:100%}
}

/* ---------- main ---------- */
.site-main{padding-block:40px 72px;padding-inline:16px}

/* ---------- buttons ---------- */
.btn{display:inline-flex;align-items:center;gap:8px;font-weight:700;font-size:15.5px;text-decoration:none;padding:13px 22px;border-radius:999px;border:1px solid transparent;transition:transform .15s ease, filter .15s ease, background .15s ease}
.btn.primary{background:var(--btn);color:#fff;box-shadow:0 10px 30px -10px rgba(61,107,255,.55)}
.btn.primary:hover{color:#fff;background:var(--btn-hover);transform:translateY(-1px)}
.btn.ghost{color:var(--fg);background:var(--surface);border-color:var(--line)}
.btn.ghost:hover{color:var(--fg);background:var(--surface-2)}

/* ---------- footer ---------- */
.site-footer{border-top:1px solid var(--line-soft);background:linear-gradient(180deg,var(--bg-2),var(--bg));color:var(--fg-mid);font-size:14.5px}
.site-footer .in{max-width:1180px;margin:0 auto;padding-block:48px 30px;padding-inline:16px}
.site-footer .cols{display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:32px}
@media (max-width:760px){.site-footer .cols{grid-template-columns:1fr 1fr}}
@media (max-width:420px){.site-footer .cols{grid-template-columns:1fr}}
.site-footer h2{font-family:var(--f-mono);font-size:11.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--fg-lo);margin:0 0 12px;font-weight:600}
.site-footer ul{list-style:none;margin:0;padding:0}
.site-footer li{margin-bottom:8px}
.site-footer a{color:var(--fg-mid);text-decoration:none}
.site-footer a:hover{color:var(--fg)}
.site-footer .about{margin:14px 0 0;line-height:1.6;max-width:36ch}
.site-footer .legal{border-top:1px solid var(--line-soft);margin-top:34px;padding-top:18px;font-size:13px;line-height:1.65;color:var(--fg-lo)}
.site-footer .legal p{margin:0 0 6px}
.site-footer .legal a{color:var(--fg-mid);text-decoration:underline}
.age{display:inline-block;font-family:var(--f-mono);font-weight:700;color:var(--warn);background:var(--warn-soft);padding:1px 8px;border-radius:6px;margin-right:8px;font-size:12px}

/* ---------- newsletter ---------- */
.signup{
  position:relative;overflow:hidden;border-radius:20px;padding:30px 30px 26px;
  background:
    radial-gradient(600px 220px at 100% 0%, rgba(157,185,255,.22), transparent 70%),
    radial-gradient(600px 240px at 0% 100%, rgba(77,124,255,.24), transparent 70%),
    var(--surface);
  border:1px solid var(--line);
}
.signup h2{font-family:var(--f-display);font-weight:800;font-size:clamp(24px,3vw,30px);letter-spacing:-.02em;margin:0 0 6px;color:var(--fg)}
.signup p{margin:0 0 16px;color:var(--fg-mid);max-width:56ch}
.signup form{display:flex;flex-wrap:wrap;gap:10px}
.signup input[type="email"]{flex:1 1 260px;min-width:0;font-family:var(--f-mono);font-size:15px;padding:13px 16px;border-radius:999px;border:1px solid var(--line);background:var(--bg-2);color:var(--fg)}
.signup input[type="email"]::placeholder{color:var(--fg-lo)}
.signup input[type="email"]:focus{outline:none;border-color:var(--side-a);box-shadow:0 0 0 4px var(--side-a-soft)}
.signup input[aria-invalid="true"]{border-color:var(--bad)}
.signup button{font-family:var(--f-body);font-weight:700;font-size:15px;background:var(--btn);color:#fff;border:none;padding:13px 24px;border-radius:999px;cursor:pointer}
.signup button:hover{background:var(--btn-hover)}
.signup .msg{flex-basis:100%;font-size:14px;margin:4px 0 0;color:var(--fg)}
.signup .fine{font-size:12.5px;color:var(--fg-lo);margin:12px 0 0}

/* ---------- article / prose pages ---------- */
.sheet{
  max-width:820px;margin:0 auto;background:linear-gradient(180deg,var(--surface),var(--bg-2));
  border:1px solid var(--line);border-radius:22px;padding:48px clamp(20px,5vw,60px) 52px;position:relative;overflow:hidden;
}
.sheet::before{content:"";position:absolute;left:0;right:0;top:0;height:3px;background:var(--gap)}
.prose{font-size:17.5px;line-height:1.75;color:#D6DEF2}
.prose h1{font-family:var(--f-display);font-weight:800;font-size:clamp(32px,5.2vw,52px);line-height:1.06;letter-spacing:-.02em;margin:10px 0 16px;color:var(--fg);text-wrap:balance}
.prose h2{font-family:var(--f-display);font-weight:700;font-size:clamp(24px,3.2vw,31px);letter-spacing:-.02em;color:var(--fg);margin:52px 0 14px;line-height:1.15;text-wrap:balance;scroll-margin-top:90px}
.prose h3{font-family:var(--f-display);font-weight:700;font-size:20px;color:var(--fg);margin:30px 0 8px}
.prose p{margin:0 0 18px}
.prose ul,.prose ol{padding-left:22px;margin:0 0 18px}
.prose li{margin-bottom:9px}
.prose li::marker{color:var(--side-a)}
.prose strong{color:var(--fg)}
.eyebrow{font-family:var(--f-mono);letter-spacing:.14em;font-size:12px;color:var(--side-a);text-transform:uppercase;margin:0;font-weight:600}
.meta{font-family:var(--f-mono);font-size:12.5px;color:var(--fg-lo);margin:14px 0 0}
.dek{font-size:20px;color:var(--fg-mid);margin:0 0 6px;line-height:1.55}
.draft-note{border:1px dashed var(--warn);color:var(--warn);background:var(--warn-soft);font-family:var(--f-mono);font-size:12.5px;padding:10px 14px;margin:0 0 24px;border-radius:var(--r-sm)}

.keyfacts{border:1px solid var(--line);background:var(--bg-2);border-radius:var(--r);padding:20px 24px;margin:30px 0 8px}
.keyfacts .t,.toc .t{font-family:var(--f-mono);font-size:11.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--profit);margin:0 0 10px;font-weight:600}
.keyfacts ul{margin:0}
.keyfacts li{margin-bottom:7px;font-size:16.5px}
nav.toc{border-top:1px solid var(--line-soft);border-bottom:1px solid var(--line-soft);padding:18px 0;margin:30px 0 0}
nav.toc .t{color:var(--fg-lo)}
nav.toc ol{columns:2;column-gap:30px;margin:0;font-size:15.5px}
@media (max-width:560px){nav.toc ol{columns:1}}
nav.toc a{color:var(--fg-mid);text-decoration:none}
nav.toc a:hover{color:var(--fg)}

.formula{font-family:var(--f-mono);font-size:14.5px;background:var(--bg-2);border:1px solid var(--line);border-left:3px solid var(--side-a);border-radius:var(--r-sm);padding:12px 16px;margin:8px 0 20px;overflow-x:auto;white-space:nowrap;color:var(--fg)}
.tw{overflow-x:auto;margin:8px 0 22px;border:1px solid var(--line);border-radius:var(--r);background:var(--bg-2)}
.prose table{border-collapse:collapse;width:100%;font-size:15px;min-width:460px}
.prose th,.prose td{text-align:right;padding:10px 14px;border-bottom:1px solid var(--line-soft);font-variant-numeric:tabular-nums}
.prose th:first-child,.prose td:first-child{text-align:left}
.prose th{font-size:11.5px;color:var(--fg-lo);text-transform:uppercase;letter-spacing:.06em;font-weight:600;background:var(--surface)}
.prose td.m{font-family:var(--f-mono);font-size:14px;color:var(--fg)}
.prose table.text td,.prose table.text th{text-align:left;vertical-align:top}
.prose caption{caption-side:bottom;text-align:left;font-size:13px;color:var(--fg-lo);padding:10px 14px}

.slip{border:1px solid var(--line);background:var(--bg-2);border-radius:var(--r);margin:16px 0 24px;overflow:hidden}
.slip .hd{font-family:var(--f-mono);font-size:11.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--fg-lo);padding:12px 18px;border-bottom:1px solid var(--line-soft);background:var(--surface)}
.slip .bd{padding:10px 18px 14px}
.slip .row{display:flex;justify-content:space-between;gap:14px;padding:8px 0;border-bottom:1px solid var(--line-soft);font-size:15.5px}
.slip .row:last-child{border-bottom:none}
.slip .row span:last-child{font-family:var(--f-mono);font-weight:600;text-align:right;color:var(--fg)}
.slip .row.total span:last-child{color:var(--profit);font-size:17px}

.cta{display:flex;flex-wrap:wrap;gap:16px;align-items:center;justify-content:space-between;border-radius:var(--r);padding:20px 22px;margin:28px 0;background:linear-gradient(90deg,var(--side-a-soft),var(--side-b-soft));border:1px solid var(--line)}
.cta p{margin:0;font-size:16.5px;color:var(--fg)}
.cta a{display:inline-block;background:var(--btn);color:#fff;text-decoration:none;font-weight:700;padding:11px 20px;border-radius:999px;font-size:15px}
.cta a:hover{color:#fff;background:var(--btn-hover)}
.warn{border:1px solid rgba(255,107,129,.35);border-left:3px solid var(--bad);background:var(--bad-soft);border-radius:var(--r-sm);padding:14px 18px;margin:18px 0 22px}
.warn p{margin:0;color:var(--fg)}
.placeholder{border:1px dashed var(--warn);color:var(--warn);font-family:var(--f-mono);font-size:12.5px;padding:18px;text-align:center;margin:20px 0;border-radius:var(--r-sm)}
details{border-bottom:1px solid var(--line-soft);padding:14px 0}
summary{cursor:pointer;font-weight:700;color:var(--fg);font-size:17.5px;list-style:none;display:flex;justify-content:space-between;gap:12px}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";font-family:var(--f-mono);color:var(--side-a);font-size:20px;line-height:1}
details[open] summary::after{content:"−"}
details p{margin:10px 0 4px;color:var(--fg-mid)}
.disclaimer{max-width:820px;margin:26px auto 0;font-size:13px;color:var(--fg-lo);line-height:1.65;text-align:center}

@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}