:root{
  --paper:#faf7f0; --paper-2:#f3eee3; --ink:#211d18; --ink-soft:#4a443b;
  --line:#e2dacb; --green:#2f5d50; --green-tint:#eef3ef; --brass:#9c7b2e;
  --brass-tint:#f7f0df; --red:#a8422d; --red-tint:#f7ece8; --blue:#38597a; --blue-tint:#eef2f6;
  --maxw:720px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0; background:var(--paper); color:var(--ink);
  font-family:"Hanken Grotesk",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
  font-size:18px; line-height:1.68; -webkit-font-smoothing:antialiased;
}
a{color:var(--green); text-decoration:none}
a:hover{text-decoration:underline; text-underline-offset:2px}

/* top bar */
.topbar{
  position:sticky; top:0; z-index:20; background:rgba(250,247,240,.92);
  backdrop-filter:blur(8px); border-bottom:1px solid var(--line);
}
.topbar-inner{max-width:var(--maxw); margin:0 auto; padding:.7rem 1.25rem;
  display:flex; align-items:baseline; justify-content:space-between; gap:1rem}
.brand{font-family:"Fraunces",Georgia,serif; font-weight:700; font-size:1.05rem;
  color:var(--ink); letter-spacing:-.01em}
.brand:hover{text-decoration:none; color:var(--green)}
.topnav a{font-size:.82rem; text-transform:uppercase; letter-spacing:.08em;
  color:var(--ink-soft); margin-left:1.1rem; font-weight:600}

/* layout */
main{max-width:var(--maxw); margin:0 auto; padding:2.4rem 1.25rem 4rem}
.eyebrow{font-family:"IBM Plex Mono",monospace; font-size:.72rem; letter-spacing:.14em;
  text-transform:uppercase; color:var(--brass); font-weight:500; margin:0 0 .6rem}
h1{font-family:"Fraunces",Georgia,serif; font-weight:600; font-size:2.15rem;
  line-height:1.16; letter-spacing:-.015em; margin:.1rem 0 1.4rem}
h2{font-family:"Fraunces",Georgia,serif; font-weight:600; font-size:1.02rem;
  letter-spacing:.02em; text-transform:uppercase; color:var(--green);
  margin:2.4rem 0 .5rem}
article p{margin:0 0 1.05rem}
article strong{font-weight:700; color:var(--ink)}
article em{font-style:italic}
article ul,article ol{margin:0 0 1.1rem; padding-left:1.2rem}
article li{margin:.32rem 0}
hr{border:0; border-top:1px solid var(--line); margin:2rem 0}

/* summary card */
.summary{background:var(--green-tint); border:1px solid var(--line);
  border-left:4px solid var(--green); border-radius:10px; padding:1.1rem 1.3rem;
  margin:0 0 2rem}
.summary h2{margin:.1rem 0 .5rem}
.summary ul{margin:0; padding-left:1.15rem}
.summary li{margin:.35rem 0}
.summary .xref{margin:.7rem 0 0; padding-top:.6rem; border-top:1px solid var(--line);
  font-size:.9rem; color:var(--ink-soft)}

/* action items */
.actions{background:var(--paper-2); border:1px solid var(--line); border-radius:10px;
  padding:1.1rem 1.3rem 1.1rem; margin:2.2rem 0 0}
.actions ul{list-style:none; margin:.4rem 0 0; padding:0}
.actions li{position:relative; padding-left:1.6rem; margin:.5rem 0}
.actions li::before{content:"✓"; position:absolute; left:0; top:0;
  color:var(--green); font-weight:700}

/* myth vs. fact */
.mythfact{margin:1.1rem 0 1.6rem; display:grid; gap:.7rem}
.mf{border:1px solid var(--line); border-radius:10px; overflow:hidden;
  box-shadow:0 1px 2px rgba(33,29,24,.05)}
.mf .myth,.mf .fact{padding:.7rem 1rem .78rem 2.55rem; position:relative; font-size:.95rem; line-height:1.55}
.mf .myth{background:var(--red-tint); border-bottom:1px solid var(--line)}
.mf .fact{background:#fff}
.mf .myth::before{content:"✕"; position:absolute; left:1rem; top:.85rem; color:var(--red); font-weight:700}
.mf .fact::before{content:"✓"; position:absolute; left:1rem; top:.85rem; color:var(--green); font-weight:700}
.mf .lbl{font-family:"IBM Plex Mono",monospace; font-size:.64rem; letter-spacing:.12em;
  text-transform:uppercase; font-weight:600; display:block; margin-bottom:.15rem}
.mf .myth .lbl{color:var(--red)}
.mf .fact .lbl{color:var(--green)}

/* model it callout */
.modelit{background:var(--brass-tint); border:1px solid #ecdcb4;
  border-left:4px solid var(--brass); border-radius:10px; padding:1.05rem 1.3rem;
  margin:1.8rem 0 0}
.modelit h2{color:var(--brass); margin:.1rem 0 .45rem}
.modelit p{margin:.2rem 0 .7rem}
.modelit .tool-link{font-weight:600; font-family:"IBM Plex Mono",monospace; font-size:.85rem}

/* formula / calculation box */
.formula{background:var(--blue-tint); border:1px solid var(--line);
  border-left:4px solid var(--blue); border-radius:10px; padding:1.05rem 1.3rem;
  margin:.6rem 0 1.4rem}
.formula h3{font-family:"Fraunces",Georgia,serif; font-weight:600; font-size:.95rem;
  text-transform:uppercase; letter-spacing:.03em; color:var(--blue); margin:0 0 .55rem}
.formula .frow{font-family:"IBM Plex Mono",monospace; font-size:.9rem; line-height:1.5;
  padding:.28rem 0; border-bottom:1px solid rgba(56,89,122,.14)}
.formula .frow:last-of-type{border-bottom:0}
.formula .ftot{font-weight:700; color:var(--ink)}
.formula .fnote{font-size:.86rem; line-height:1.55; color:var(--ink-soft); margin:.65rem 0 0}

/* worked-example / walkthrough box */
.example{background:#fff; border:1px solid var(--line); border-left:4px solid var(--green);
  border-radius:10px; padding:1.1rem 1.3rem 1.25rem; margin:.6rem 0 1.6rem;
  box-shadow:0 1px 2px rgba(33,29,24,.05)}
.example .ex-label{display:inline-block; font-family:"IBM Plex Mono",monospace;
  font-size:.66rem; letter-spacing:.12em; text-transform:uppercase; color:var(--green);
  background:var(--green-tint); border:1px solid #cfe0d8; border-radius:999px;
  padding:.16rem .6rem; margin:0 0 .55rem}
.example h3{font-family:"Fraunces",Georgia,serif; font-weight:600; font-size:1.12rem;
  line-height:1.25; letter-spacing:-.01em; color:var(--ink); margin:.1rem 0 .3rem}
.example>p{margin:.2rem 0 .8rem; font-size:.96rem}
.example .step{font-family:"IBM Plex Mono",monospace; font-weight:500; font-size:.74rem;
  text-transform:uppercase; letter-spacing:.08em; color:var(--green);
  margin:1.15rem 0 .5rem; padding-top:.9rem; border-top:1px solid var(--line)}
.example .step:first-of-type{border-top:0; padding-top:0; margin-top:.6rem}
.example .step .num{color:var(--brass); margin-right:.4rem}
.example table td.n,.example table th.n{text-align:right;
  font-family:"IBM Plex Mono",monospace; font-variant-numeric:tabular-nums; white-space:nowrap}
.example tfoot td{border-top:2px solid var(--green); font-weight:700; background:var(--green-tint)}
.example .ex-total{background:var(--green-tint); border:1px solid #cfe0d8; border-radius:8px;
  padding:.6rem .85rem; margin:.6rem 0 .3rem; font-size:.95rem}
.example .ex-total strong{color:var(--ink)}
.example caption{caption-side:bottom; text-align:left; color:var(--ink-soft);
  font-size:.8rem; font-style:italic; line-height:1.5; margin-top:.45rem}

/* calc chain + term list */
.calc-chain{font-family:"IBM Plex Mono",monospace; font-size:.88rem; line-height:1.7;
  background:var(--paper-2); border:1px solid var(--line); border-radius:8px;
  padding:.7rem .9rem; margin:.3rem 0 1rem; text-align:center}
.calc-chain .arw{color:var(--brass); white-space:nowrap}
.calc-chain strong{color:var(--ink)}
.terms{list-style:none; margin:0 0 1.1rem; padding:0}
.terms li{margin:.45rem 0}
.terms .t{font-weight:700; color:var(--ink)}

/* references */
.references{margin:2.6rem 0 0; border-top:1px solid var(--line); padding-top:1.2rem}
.references h2{margin:0 0 .5rem}
.references ol{margin:0; padding-left:1.2rem; font-size:.92rem}
.references li{margin:.4rem 0; color:var(--ink-soft)}
.references a{word-break:break-word}

/* highlight */
mark{background:#f6e4b4; color:var(--ink); padding:.04em .18em; border-radius:3px;
  box-shadow:0 0 0 1px rgba(156,123,46,.25)}

/* tables */
.mono{font-family:"IBM Plex Mono",monospace; font-variant-numeric:tabular-nums; font-size:.92em; white-space:nowrap}

/* ages & deadlines — one row per age, milestones stacked & grouped */
.ages td{vertical-align:top}
.ages .sub{padding:.4rem 0; border-top:1px dashed var(--line)}
.ages .sub:first-child{padding-top:0; border-top:0}
.ages .sub:last-child{padding-bottom:0}
.ages .ms{font-weight:700; color:var(--ink); display:block}
.ages .dt{display:block; margin-top:.1rem}
.ages .do{display:block; margin-top:.28rem; font-size:.86rem; color:var(--green)}
.ages .do::before{content:"→ "; color:var(--brass); font-weight:700}
.ages .ref{font-family:"IBM Plex Mono",monospace; font-size:.82rem; white-space:nowrap}
.ages tr.flag{background:var(--brass-tint)!important}
.ages tr.flag td:first-child{box-shadow:inset 3px 0 0 var(--brass)}
.tablewrap{overflow-x:auto; margin:0 0 1.2rem}
table{border-collapse:collapse; width:100%; font-size:.9rem;
  font-variant-numeric:tabular-nums}
th,td{border:1px solid var(--line); padding:.5rem .65rem; text-align:left}
th{background:var(--paper-2); font-weight:600; font-family:"Hanken Grotesk",sans-serif}
tbody tr:nth-child(even){background:rgba(243,238,227,.4)}

/* prev / next */
.pager{display:flex; gap:1rem; margin-top:3rem; border-top:1px solid var(--line);
  padding-top:1.4rem}
.pager a{flex:1; border:1px solid var(--line); border-radius:10px; padding:.85rem 1rem;
  background:#fff; transition:border-color .15s}
.pager a:hover{border-color:var(--green); text-decoration:none}
.pager .dir{display:block; font-family:"IBM Plex Mono",monospace; font-size:.7rem;
  letter-spacing:.1em; text-transform:uppercase; color:var(--brass); margin-bottom:.2rem}
.pager .ttl{color:var(--ink); font-weight:600; font-size:.95rem; line-height:1.3}
.pager .next{text-align:right}

/* index / home */
.hero{margin:1rem 0 2.6rem}
.hero .eyebrow{margin-bottom:.8rem}
.hero h1{font-size:2.7rem; margin:.2rem 0 .6rem}
.hero .sub{font-family:"Fraunces",serif; font-size:1.25rem; font-style:italic;
  color:var(--ink-soft); font-weight:400; margin:0 0 1rem}
.hero .lede{font-size:1.02rem}
.byline{font-family:"IBM Plex Mono",monospace; font-size:.8rem; color:var(--ink-soft);
  margin-top:1rem}
.byline a{color:var(--green)}

.part{margin:2.8rem 0 0}
.part-head{border-top:2px solid var(--green); padding-top:1rem}
.part-num{font-family:"IBM Plex Mono",monospace; color:var(--brass); font-weight:500;
  font-size:.8rem; letter-spacing:.12em}
.part-head h2{font-family:"Fraunces",serif; text-transform:none; color:var(--ink);
  font-size:1.55rem; letter-spacing:-.01em; margin:.25rem 0 .1rem}
.part-head .tag{font-family:"IBM Plex Mono",monospace; font-size:.75rem;
  color:var(--green); text-transform:uppercase; letter-spacing:.1em}
.part-intro{color:var(--ink-soft); font-size:.98rem; margin:.8rem 0 1.3rem}

.chapter-list{display:grid; gap:.6rem; margin:0}
.ch-card{display:flex; gap:.9rem; align-items:flex-start; padding:.85rem 1rem;
  border:1px solid var(--line); border-radius:10px; background:#fff;
  transition:border-color .15s}
.ch-card:hover{border-color:var(--green); text-decoration:none}
.ch-card .n{font-family:"Fraunces",serif; font-weight:700; color:var(--brass);
  font-size:1.2rem; line-height:1.2; min-width:1.6rem}
.ch-card .body .t{font-weight:700; color:var(--ink); display:block; line-height:1.3}
.ch-card .body .d{color:var(--ink-soft); font-size:.88rem; display:block; margin-top:.15rem}

.disclaimer{margin-top:3rem; padding-top:1.3rem; border-top:1px solid var(--line);
  font-size:.82rem; color:var(--ink-soft); font-style:italic}

/* glossary */
.glossary-list{margin:1.5rem 0 0}
.gitem{padding:.9rem 0; border-bottom:1px solid var(--line)}
.gitem .term{font-family:"Fraunces",serif; font-weight:600; font-size:1.08rem;
  color:var(--ink)}
.gitem .def{color:var(--ink-soft); font-size:.95rem; margin:.25rem 0 .3rem}
.gitem .see{font-family:"IBM Plex Mono",monospace; font-size:.78rem}
.jump{display:flex; flex-wrap:wrap; gap:.4rem; margin:1.2rem 0 0}
.jump a{font-family:"IBM Plex Mono",monospace; font-size:.8rem; padding:.2rem .5rem;
  border:1px solid var(--line); border-radius:6px; background:#fff}
.galpha{font-family:"Fraunces",serif; font-size:1.4rem; color:var(--brass);
  font-weight:700; margin:1.8rem 0 .3rem; border-bottom:2px solid var(--line);
  padding-bottom:.2rem}

@media (max-width:560px){
  body{font-size:17px}
  h1{font-size:1.8rem}
  .hero h1{font-size:2.1rem}
  main{padding:1.8rem 1.05rem 3rem}
  .pager{flex-direction:column}
}