:root{
  --ground:#F2F3EF;
  --surface:#FFFFFF;
  --surface-2:#EAECE5;
  --ink:#15181A;
  --ink-2:#3A403E;
  --muted:#666C68;
  --rule:#D7DAD2;
  --rule-soft:#E5E8E0;
  --accent:#8A6A12;
  --accent-2:#6B5210;
  --accent-soft:#F0E8D3;
  --crit:#93321F;
  --ok:#2E6247;
  --shadow:0 1px 2px rgba(21,24,26,.05), 0 8px 24px -16px rgba(21,24,26,.18);
}
@media (prefers-color-scheme: dark){
  :root:not([data-theme="light"]){
    --ground:#121412;
    --surface:#1A1D1A;
    --surface-2:#22261F;
    --ink:#E9EAE4;
    --ink-2:#C2C6BD;
    --muted:#9AA097;
    --rule:#2E332C;
    --rule-soft:#262A24;
    --accent:#D8B463;
    --accent-2:#EBCE8C;
    --accent-soft:#2A2517;
    --crit:#DC8C7A;
    --ok:#7FC2A2;
    --shadow:0 1px 2px rgba(0,0,0,.4), 0 8px 24px -16px rgba(0,0,0,.6);
  }
}
:root[data-theme="dark"]{
  --ground:#121412;
  --surface:#1A1D1A;
  --surface-2:#22261F;
  --ink:#E9EAE4;
  --ink-2:#C2C6BD;
  --muted:#9AA097;
  --rule:#2E332C;
  --rule-soft:#262A24;
  --accent:#D8B463;
  --accent-2:#EBCE8C;
  --accent-soft:#2A2517;
  --crit:#DC8C7A;
  --ok:#7FC2A2;
  --shadow:0 1px 2px rgba(0,0,0,.4), 0 8px 24px -16px rgba(0,0,0,.6);
}

*{box-sizing:border-box}
body{
  margin:0;
  background:var(--ground);
  color:var(--ink);
  font-family:"IBM Plex Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  font-size:16.5px;
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
}

/* ---------- shell ---------- */
.shell{display:flex;align-items:flex-start;min-height:100vh}

.rail{
  position:sticky;top:0;flex:0 0 306px;width:306px;height:100vh;
  display:flex;flex-direction:column;
  background:var(--surface);
  border-right:1px solid var(--rule);
}
.rail-head{
  padding:26px 24px 16px;border-bottom:1px solid var(--rule-soft);
  display:flex;flex-direction:column;gap:14px;
}
.brand{display:flex;flex-direction:column;gap:3px;text-decoration:none;color:inherit}
.brand-name{
  font-family:Newsreader,Georgia,serif;font-size:25px;font-weight:600;
  letter-spacing:-.015em;line-height:1.1;
}
.brand-sub{
  font-family:"IBM Plex Mono",ui-monospace,monospace;font-size:10.5px;
  letter-spacing:.14em;text-transform:uppercase;color:var(--muted);
}
.find{position:relative}
.find input{
  width:100%;padding:8px 10px 8px 30px;
  font:inherit;font-size:13.5px;
  color:var(--ink);background:var(--ground);
  border:1px solid var(--rule);border-radius:4px;
}
.find input::placeholder{color:var(--muted)}
.find input:focus{outline:2px solid var(--accent);outline-offset:1px;border-color:transparent}
.find svg{position:absolute;left:9px;top:50%;transform:translateY(-50%);width:14px;height:14px;stroke:var(--muted);fill:none;stroke-width:1.8}

nav.toc{overflow-y:auto;padding:14px 12px 40px;flex:1}
nav.toc ul{list-style:none;margin:0;padding:0}
.toc-chapter{margin-bottom:6px}
.toc-chapter > a{
  display:flex;gap:9px;align-items:baseline;
  padding:8px 12px;border-radius:4px;text-decoration:none;color:var(--ink);
  font-family:Newsreader,Georgia,serif;font-size:16.5px;font-weight:500;line-height:1.25;
}
.toc-chapter > a:hover{background:var(--surface-2)}
.toc-num{
  font-family:"IBM Plex Mono",monospace;font-size:11px;color:var(--accent);
  flex:0 0 auto;letter-spacing:.02em;
}
.toc-sections{margin:1px 0 10px 0;border-left:1px solid var(--rule-soft);margin-left:19px}
.toc-sections a{
  display:block;padding:4.5px 10px 4.5px 13px;margin-left:-1px;
  border-left:2px solid transparent;
  text-decoration:none;color:var(--muted);font-size:13.2px;line-height:1.4;
}
.toc-sections a:hover{color:var(--ink);background:var(--surface-2)}
.toc-sections a.on{color:var(--accent-2);border-left-color:var(--accent);font-weight:500}
nav.toc a:focus-visible,.brand:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.hidden{display:none !important}

/* ---------- reading column ---------- */
main{flex:1;min-width:0;padding:0 clamp(20px,5vw,76px) 140px}
.doc{max-width:790px;margin:0 auto}

/* cover */
.cover{padding:88px 0 0}
.cover h1{
  font-family:Newsreader,Georgia,serif;font-size:clamp(40px,6vw,60px);
  font-weight:600;letter-spacing:-.025em;line-height:1.02;margin:0 0 20px;
  text-wrap:balance;
}
.cover > p:first-of-type{
  font-size:19px;color:var(--ink-2);max-width:56ch;line-height:1.5;
}

/* chapter opener */
h1{
  font-family:Newsreader,Georgia,serif;font-weight:600;letter-spacing:-.02em;
  font-size:clamp(31px,4.4vw,42px);line-height:1.1;margin:0;text-wrap:balance;
}
.chapter-open{
  margin:0 0 46px;padding:96px 0 22px;border-bottom:2px solid var(--ink);
  scroll-margin-top:0;
}
.chapter-open .eyebrow{
  font-family:"IBM Plex Mono",monospace;font-size:11px;letter-spacing:.18em;
  text-transform:uppercase;color:var(--accent);margin:0 0 14px;
}

h2{
  font-family:Newsreader,Georgia,serif;font-weight:600;letter-spacing:-.012em;
  font-size:26px;line-height:1.22;margin:58px 0 16px;
  scroll-margin-top:24px;text-wrap:balance;
  display:flex;gap:11px;align-items:baseline;
}
h2 .n{
  font-family:"IBM Plex Mono",monospace;font-size:13px;font-weight:500;
  color:var(--accent);flex:0 0 auto;letter-spacing:0;
}
h3{
  font-family:"IBM Plex Sans",sans-serif;font-weight:600;
  font-size:15.5px;line-height:1.35;margin:36px 0 10px;
  letter-spacing:.005em;scroll-margin-top:24px;
}

p{margin:0 0 15px;max-width:70ch}
strong{font-weight:600;color:var(--ink)}
em{font-style:italic;color:var(--ink-2)}
code{
  font-family:"IBM Plex Mono",monospace;font-size:.87em;
  background:var(--surface-2);padding:1px 5px;border-radius:3px;
  border:1px solid var(--rule-soft);
}
hr{
  border:0;height:1px;background:var(--rule);
  margin:46px 0;max-width:70ch;
}

ul,ol{margin:0 0 16px;padding-left:22px;max-width:70ch}
li{margin:0 0 7px;padding-left:3px}
li::marker{color:var(--accent)}
ul ul,ol ol,ul ol{margin:7px 0 0}

/* callout */
blockquote{
  margin:26px 0;padding:16px 20px;max-width:70ch;
  background:var(--accent-soft);
  border-left:3px solid var(--accent);
  border-radius:0 4px 4px 0;
}
blockquote p{margin:0 0 10px;font-size:15.5px;color:var(--ink-2)}
blockquote p:last-child{margin-bottom:0}
blockquote ul,blockquote ol{margin-bottom:0;font-size:15.5px;color:var(--ink-2)}
blockquote strong{color:var(--ink)}

/* tables */
.tw{
  overflow-x:auto;margin:24px 0 30px;
  border:1px solid var(--rule);border-radius:5px;background:var(--surface);
  box-shadow:var(--shadow);
}
table{border-collapse:collapse;width:100%;font-size:14.6px;line-height:1.5}
thead th{
  font-family:"IBM Plex Mono",monospace;font-weight:500;font-size:10.5px;
  letter-spacing:.11em;text-transform:uppercase;color:var(--muted);
  text-align:left;padding:11px 16px;
  background:var(--surface-2);border-bottom:1px solid var(--rule);
  white-space:nowrap;
}
tbody td{
  padding:11px 16px;border-bottom:1px solid var(--rule-soft);
  vertical-align:top;font-variant-numeric:tabular-nums;
}
tbody tr:last-child td{border-bottom:0}
tbody td:first-child{color:var(--ink)}
tbody td strong{white-space:normal}
table p{margin:0;max-width:none}

/* mobile */
.mtop{display:none}
@media (max-width:940px){
  .mtop{
    display:flex;position:sticky;top:0;z-index:30;
    align-items:center;gap:12px;padding:11px 16px;
    background:var(--surface);border-bottom:1px solid var(--rule);
  }
  .mtop .brand-name{font-size:19px}
  .burger{
    margin-left:auto;display:flex;align-items:center;gap:7px;
    font:inherit;font-size:13px;color:var(--ink);cursor:pointer;
    background:var(--ground);border:1px solid var(--rule);
    border-radius:4px;padding:6px 11px;
  }
  .shell{flex-direction:column}
  .rail{
    position:fixed;top:0;left:0;bottom:0;z-index:40;
    width:min(88vw,320px);flex-basis:auto;height:100dvh;
    transform:translateX(-101%);transition:transform .22s ease;
    box-shadow:0 0 40px rgba(0,0,0,.25);
  }
  .rail.open{transform:none}
  .scrim{
    position:fixed;inset:0;z-index:35;background:rgba(10,12,10,.45);
    opacity:0;pointer-events:none;transition:opacity .22s ease;
  }
  .scrim.on{opacity:1;pointer-events:auto}
  main{width:100%;padding:0 18px 100px}
  .cover{padding:44px 0 0}
  .chapter-open{padding:54px 0 18px;margin-bottom:34px}
  h2{margin-top:44px;font-size:23px}
}
@media (prefers-reduced-motion: reduce){
  *{transition:none !important;scroll-behavior:auto !important}
}
html{scroll-behavior:smooth}

@media print{
  .rail,.mtop,.scrim{display:none !important}
  body{background:#fff;color:#000;font-size:10.5pt}
  main{padding:0}
  .doc{max-width:none}
  .chapter-open{break-before:page;padding-top:0}
  .cover{padding-top:0}
  h2,h3{break-after:avoid}
  .tw,blockquote,table tr{break-inside:avoid}
  .tw{box-shadow:none}
}