/* Layout: one reading column like the printed book, wider bands for the home page. */
:root{
  --paper:#faf7f0; --ink:#1b211e; --green:#2f5d50; --deep:#17372f; --muted:#6e7772;
  --panel:#f3f6f3; --rule:#dce6e0; --on-deep:#faf7f0; --field:#ffffff;
  --serif:"Noto Serif",Georgia,"Times New Roman",serif;
  --sans:"Noto Sans",system-ui,-apple-system,"Segoe UI",Arial,sans-serif;
  --measure:38rem;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --paper:#121714; --ink:#e7ebe8; --green:#8fbfa9; --deep:#0c1f19; --muted:#a3aca7;
  --panel:#1a221e; --rule:#2c3a33; --on-deep:#e7ebe8; --field:#0f1411; color-scheme:dark}}
:root[data-theme="dark"]{
  --paper:#121714; --ink:#e7ebe8; --green:#8fbfa9; --deep:#0c1f19; --muted:#a3aca7;
  --panel:#1a221e; --rule:#2c3a33; --on-deep:#e7ebe8; --field:#0f1411; color-scheme:dark}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--serif);font-size:1.0625rem;line-height:1.65}
a{color:var(--green)}
a:focus-visible,button:focus-visible,input:focus-visible{outline:2px solid var(--green);outline-offset:2px}
.wrap{max-width:62rem;margin:0 auto;padding-inline:1.25rem}
.col{max-width:var(--measure);margin:0 auto;padding-inline:1.25rem}
header.top{border-bottom:1px solid var(--rule)}
header.top .wrap{display:flex;flex-wrap:wrap;gap:.75rem 1.5rem;align-items:center;justify-content:space-between;padding-block:1rem}
.mark{font-family:var(--sans);font-weight:700;letter-spacing:.14em;text-transform:uppercase;font-size:.8rem;color:var(--ink);text-decoration:none;line-height:1.3}
.mark span{color:var(--green)}
nav.links{display:flex;flex-wrap:wrap;gap:1.25rem;font-family:var(--sans);font-size:.9rem}
nav.links a{color:var(--ink);text-decoration:none}
nav.links a:hover{color:var(--green)}
.label{font-family:var(--sans);font-weight:700;font-size:.75rem;letter-spacing:.14em;text-transform:uppercase;color:var(--green)}
h1,h2,h3{text-wrap:balance;line-height:1.2;font-weight:700}
.btn{display:inline-block;font-family:var(--sans);font-weight:600;font-size:.95rem;padding:.8rem 1.2rem;border-radius:3px;text-decoration:none;border:1px solid var(--green);cursor:pointer}
.btn.solid{background:var(--green);color:var(--paper)}
.btn.line{background:transparent;color:var(--green)}
.btn:hover{filter:brightness(1.08)}
/* home */
.hero{padding-block:4.5rem 3.5rem}
.hero h1{font-size:clamp(2.4rem,6vw,4.1rem);margin:.6rem 0 1rem;letter-spacing:-.01em}
.hero h1 .plus{color:var(--green);font-weight:400}
.hero p.lede{font-size:1.2rem;max-width:34rem;margin:0 0 2rem;color:var(--ink)}
.actions{display:flex;flex-wrap:wrap;gap:.75rem}
.ground{border-top:1px solid var(--rule);padding-block:3.5rem}
.two{display:grid;grid-template-columns:1fr 1fr;gap:2.5rem}
.two>*{min-width:0}
@media (max-width:760px){.two{grid-template-columns:1fr}}
.thesis-lines p{margin:.2rem 0}
.thesis-lines p.big{font-size:1.35rem;font-weight:600;margin:1rem 0}
.keys{display:grid;grid-template-columns:repeat(3,1fr);gap:1.25rem;margin-top:1.5rem}
.keys>div{min-width:0;border-top:3px solid var(--green);padding-top:.9rem}
.keys h3{font-family:var(--sans);font-size:.8rem;letter-spacing:.14em;text-transform:uppercase;margin:0 0 .4rem;color:var(--green)}
.keys p{margin:0;font-size:1rem}
@media (max-width:760px){.keys{grid-template-columns:1fr}}
.deep{background:var(--deep);color:var(--on-deep)}
.deep .label{color:var(--on-deep);opacity:.8}
.deep a{color:var(--on-deep)}
.signup{display:flex;flex-wrap:wrap;gap:.6rem;margin-top:1.25rem}
.signup input{flex:1 1 16rem;min-width:0;font:inherit;font-family:var(--sans);font-size:1rem;padding:.8rem .9rem;border:1px solid var(--rule);border-radius:3px;background:var(--field);color:var(--ink)}
.deep .signup .btn{background:var(--on-deep);color:var(--deep);border-color:var(--on-deep)}
.formmsg{font-family:var(--sans);font-size:.9rem;min-height:1.4rem;margin-top:.6rem}
.product{display:grid;grid-template-columns:repeat(2,1fr);gap:1.25rem;margin-top:1.5rem}
.product>div{min-width:0;border:1px solid var(--rule);padding:1.4rem;background:var(--panel)}
.product h3{margin:0 0 .25rem;font-size:1.2rem}
.product .price{font-family:var(--sans);font-size:1.6rem;font-weight:700;color:var(--green);font-variant-numeric:tabular-nums;margin:.5rem 0 1rem}
.product p{margin:.3rem 0 1rem;font-size:1rem}
@media (max-width:640px){.product{grid-template-columns:1fr}}
.muted{color:var(--muted)}
footer.foot{border-top:1px solid var(--rule);padding-block:2rem;font-family:var(--sans);font-size:.85rem;color:var(--muted)}
footer.foot .wrap{display:flex;flex-wrap:wrap;gap:.5rem 1.5rem;justify-content:space-between}
/* reader */
.chapter-head{padding-block:3rem 1rem;text-align:left}
.chapter-head h1{font-size:clamp(2rem,5vw,2.8rem);margin:.4rem 0 .25rem}
.chapter-head .sub{font-style:italic;color:var(--muted);font-size:1.15rem}
.section-head{font-family:var(--sans);font-weight:700;font-size:.8rem;letter-spacing:.14em;text-transform:uppercase;color:var(--ink);margin:2.4rem 0 .6rem}
.ref{font-family:var(--sans);font-size:.75rem;letter-spacing:.1em;text-transform:uppercase;color:var(--muted);margin:1.6rem 0 .4rem}
p.v{margin:.35rem 0}
p.v sup{font-family:var(--sans);font-weight:700;font-size:.7rem;color:var(--green);margin-right:.35rem;vertical-align:.35em}
aside.note{font-family:var(--sans);font-size:.98rem;line-height:1.62;background:var(--panel);border:1px solid var(--rule);padding:1.2rem 1.3rem;margin:1.6rem 0}
aside.note .label{display:block;margin-bottom:.6rem}
aside.note p{margin:.55rem 0}
aside.note ul{margin:.4rem 0;padding-left:1.2rem}
aside.note.bf{border-color:var(--green)}
.pager{display:flex;flex-wrap:wrap;gap:1rem;justify-content:space-between;font-family:var(--sans);border-top:1px solid var(--rule);margin-top:3rem;padding-block:1.5rem 3rem}
.locked{border:1px solid var(--green);padding:1.4rem;margin:2rem 0;font-family:var(--sans)}
.locked p{margin:.3rem 0 1rem}
.toc{list-style:none;padding:0;margin:1.5rem 0 3rem;display:grid;grid-template-columns:repeat(2,1fr);gap:0 2rem}
.toc li{min-width:0;display:flex;gap:.75rem;align-items:baseline;border-bottom:1px solid var(--rule);padding:.6rem 0}
.toc .n{font-family:var(--sans);font-weight:700;color:var(--green);min-width:2.2rem;font-variant-numeric:tabular-nums}
.toc .t{flex:1;min-width:0}
.toc .tag{font-family:var(--sans);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted)}
@media (max-width:640px){.toc{grid-template-columns:1fr}}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}