:root{--bg:#fbf6ee;--surface:#fffdf8;--ink:#2b1d12;--muted:#5c4838;--accent:#1f4f9a;--accent-ink:#ffffff;--accent2:#c23a2b;--line:#e8d9c2;--hero-ink:#ffffff;--r:18px;--maxw:1180px;--measure:66ch;--hf:'Delius', 'Trebuchet MS', sans-serif;--bf:'Open Sans', system-ui, 'Segoe UI', sans-serif}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.65 var(--bf)}
img{max-width:100%;height:auto;display:block}
a{color:var(--accent);text-underline-offset:.18em}
h1,h2,h3,h4{font-family:var(--hf);line-height:1.18;margin:1.6em 0 .5em;font-weight:400;letter-spacing:0}
h1{font-size:clamp(2rem,5vw,3.5rem);margin-top:0}
h2{font-size:clamp(1.4rem,3vw,2rem)}h3{font-size:1.2rem}
p,ul,ol,table,details{margin:0 0 1.1em}
.wrap{max-width:max(var(--maxw),min(88vw,1760px));margin:0 auto;padding:0 20px}
@media(min-width:1800px){body article.prose>:is(p,ul,ol,h2,h3,h4,blockquote,dl,details,.callout,.disclosure,.table-wrap){max-width:52rem}}
.skip{position:absolute;left:-999px}.skip:focus{left:10px;top:10px;background:var(--surface);padding:8px;z-index:9}
header.site{border-bottom:1px solid var(--line);background:var(--surface)}
header.site .wrap{display:flex;align-items:center;justify-content:space-between;gap:16px;padding-top:14px;padding-bottom:14px;flex-wrap:wrap}
.brand{font-family:var(--hf);font-weight:800;font-size:1.25rem;color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:10px}
.brand svg{flex:none}
nav.main ul{list-style:none;display:flex;flex-wrap:wrap;gap:4px 18px;margin:0;padding:0}
nav.main a{color:var(--ink);text-decoration:none;font-size:.95rem;padding:4px 0;border-bottom:2px solid transparent}
nav.main a[aria-current]{border-color:var(--accent)}
.menu-btn{display:none}
@media(max-width:760px){.menu-btn{display:inline-block;background:none;border:1px solid var(--line);color:var(--ink);border-radius:var(--r);padding:6px 12px;font:inherit}
nav.main{width:100%;display:none}nav.main.open{display:block}nav.main ul{flex-direction:column;gap:6px}}
.hero{position:relative;overflow:hidden}
.hero .wrap{padding-top:56px;padding-bottom:56px}
.hero .lead{font-size:1.18rem;color:var(--muted);max-width:60ch}
.hero.full{color:var(--hero-ink);min-height:440px;display:flex;align-items:flex-end}
.hero.full img.bg{position:absolute;inset:0;width:100%;height:100%;object-fit:cover}
.hero.full::after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,.05),rgba(0,0,0,.62))}
.hero.full .wrap{position:relative;z-index:1;width:100%}.hero.full .lead{color:inherit;opacity:.92}
.hero.split .wrap{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:center}
.hero.split img{border-radius:var(--r);aspect-ratio:4/3;object-fit:cover;width:100%}
.hero.banner img{width:100%;max-height:380px;object-fit:cover;border-radius:var(--r);margin-top:28px}
.hero.plain{background:var(--surface);border-bottom:1px solid var(--line)}
@media(max-width:760px){.hero.split .wrap{grid-template-columns:1fr}.hero.full{min-height:340px}.hero .wrap{padding-top:36px;padding-bottom:36px}}
.page{display:grid;gap:48px;padding-top:40px;padding-bottom:64px}
.page.toc-layout{grid-template-columns:220px minmax(0,1fr)}
.page.toc-layout .toc{position:sticky;top:20px;align-self:start;font-size:.92rem;border-left:3px solid var(--accent);padding-left:14px}
.page.toc-layout .toc ul{list-style:none;padding:0;margin:0}.page.toc-layout .toc li{margin:.35em 0}
.page.toc-layout .toc a{color:var(--muted);text-decoration:none}
@media(max-width:860px){.page.toc-layout{grid-template-columns:1fr}.page.toc-layout .toc{position:static}}
/* Content uses the full container width (cards, grids, tables); only running text keeps a readable measure. */
article.prose{max-width:none;min-width:0}
article.prose>:is(p,ul,ol,h2,h3,h4,blockquote,dl,details,.callout,.disclosure,.table-wrap){max-width:47.5rem;margin-left:auto;margin-right:auto}
.page.toc-layout article.prose>*{margin-left:0;margin-right:0}
/* A heading that introduces a full-width block (cards, grid, table) lines up with that block, not the text column. */
body article.prose>:is(h2,h3):has(+ :is(.cards,nav,div,table,section,ul.grid)){max-width:none;margin-left:0;margin-right:0}
.page.wide article.prose>*{max-width:none}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:18px;margin:0 0 1.4em}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--r);padding:20px}
.card h3{margin-top:0}.card p:last-child{margin-bottom:0}
a.card{display:block;color:var(--ink);text-decoration:none}a.card:hover{border-color:var(--accent)}
.callout{border-left:4px solid var(--accent2);background:var(--surface);padding:14px 18px;border-radius:0 var(--r) var(--r) 0;margin:0 0 1.2em}
.table-wrap{overflow-x:auto;margin:0 0 1.2em}
table{border-collapse:collapse;width:100%;font-size:.95rem}
th,td{border-bottom:1px solid var(--line);padding:9px 10px;text-align:left;vertical-align:top}
th{font-family:var(--hf);background:var(--surface)}
details{border:1px solid var(--line);border-radius:var(--r);padding:10px 16px;background:var(--surface)}
summary{cursor:pointer;font-weight:600}
.steps{counter-reset:s;list-style:none;padding:0}.steps li{counter-increment:s;position:relative;padding-left:44px;margin-bottom:1em}
.steps li::before{content:counter(s);position:absolute;left:0;top:0;width:30px;height:30px;border-radius:50%;background:var(--accent);color:var(--accent-ink);display:grid;place-items:center;font-weight:700;font-size:.9rem}
.btn{display:inline-block;background:var(--accent);color:var(--accent-ink);padding:10px 18px;border-radius:var(--r);text-decoration:none;font-weight:600;border:0;font:inherit;cursor:pointer}
.aff{border:1px dashed var(--accent);border-radius:var(--r);padding:16px 18px;margin:0 0 1.2em;background:var(--surface)}
.aff .tag{font-size:.75rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted)}
.disclosure{font-size:.88rem;color:var(--muted);border:1px solid var(--line);border-radius:var(--r);padding:10px 14px;margin:0 0 1.6em}
.meta{font-size:.88rem;color:var(--muted)}
dl dt{font-family:var(--hf);font-weight:700;margin-top:1em}dl dd{margin:.2em 0 0 0;color:var(--ink)}
footer.site{border-top:1px solid var(--line);background:var(--surface);font-size:.92rem;color:var(--muted)}
footer.site .wrap{padding-top:32px;padding-bottom:32px;display:grid;gap:18px}
footer.site ul{list-style:none;padding:0;margin:0;display:flex;flex-wrap:wrap;gap:6px 18px}
footer.site a{color:var(--muted)}
.tt{font-size:17px}
.tt h1,.tt h2,.tt h3{font-weight:400;color:#3a2614}
/* Header: cream with a wood-plank rail underneath */
.tt header.site{background:#fffdf8;border-bottom:0;position:relative}
.tt header.site::after{content:"";display:block;height:12px;background:repeating-linear-gradient(90deg,rgba(0,0,0,0) 0 180px,rgba(60,35,15,.35) 180px 182px),repeating-linear-gradient(0deg,#b9814a 0 3px,#a8713d 3px 5px,#c08a53 5px 9px,#a36b38 9px 12px)}
.tt .brand{font-weight:400;font-size:1.6rem;color:#3a2614}
.tt nav.main ul{gap:4px 8px}
.tt nav.main a{font-size:.95rem;font-weight:600;padding:6px 14px;border:0;border-radius:999px;color:#3a2614}
.tt nav.main a:hover{background:#f3e7d4}
.tt nav.main a[aria-current]{background:#2457a6;color:#fff}
.tt .menu-btn{border-radius:999px;border-color:#d9c3a3}
/* Hero */
.tt .hero{background:linear-gradient(180deg,#f6ead7,#fbf6ee 85%)}
.tt .hero .kicker{display:inline-block;margin:0 0 1em;padding:5px 14px 5px 30px;border-radius:999px;background:#fffdf8;border:1px solid #e3cfb1;color:#6b4423;font-size:.82rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase;position:relative}
.tt .hero .kicker::before{content:"";position:absolute;left:11px;top:50%;width:11px;height:11px;margin-top:-5.5px;border-radius:50%;background:#c23a2b;box-shadow:inset -2px -2px 0 rgba(0,0,0,.18)}
.tt .hero h1{max-width:20ch;line-height:1.12}
.tt .hero .lead{color:#4f3c2c;max-width:58ch}
.tt .hero.split .wrap{grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);gap:56px;padding-top:56px;padding-bottom:56px}
.tt .hero.split img{border-radius:28px;border:10px solid #fffdf8;box-shadow:0 0 0 1px #e3cfb1,0 18px 40px rgba(90,55,25,.18)}
.tt .hero.plain{border-bottom:0}
.tt .hero.plain .wrap{padding-top:52px;padding-bottom:48px}
.tt .hero.plain .wrap:has(.art){display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);grid-template-rows:1fr auto auto auto 1fr;column-gap:56px}
.tt .hero.plain .wrap:has(.art)>:not(.art){grid-column:1}
.tt .hero.plain .wrap:has(.art)>.kicker{grid-row:2;justify-self:start}.tt .hero.plain .wrap:has(.art)>h1{grid-row:3}.tt .hero.plain .wrap:has(.art)>.lead{grid-row:4}
.tt .hero.plain .art{grid-column:2;grid-row:1/6;align-self:center;background:#fffdf8;border-radius:32px;border:1px solid #e8d9c2;padding:22px 24px 10px;box-shadow:0 18px 40px rgba(90,55,25,.12)}
.tt .art .stacker{width:100%;height:auto;display:block;max-height:360px}
.tt .hero.banner img{border-radius:24px;border:8px solid #fffdf8;box-shadow:0 0 0 1px #e3cfb1;max-height:400px}
@media(min-width:1800px){.tt .hero.plain .wrap,.tt .hero.split .wrap{padding-top:84px;padding-bottom:84px}.tt .art .stacker{max-height:440px}.tt .hero .lead{font-size:1.3rem}}
@media(max-width:860px){.tt .hero.plain .wrap:has(.art){grid-template-columns:1fr;grid-template-rows:none}.tt .hero.plain .wrap:has(.art)>*{grid-row:auto!important}.tt .hero.plain .art{grid-column:1;margin-top:26px;max-width:380px}.tt .hero.split .wrap{grid-template-columns:1fr}}
@media(max-width:760px){.tt .brand{font-size:1.35rem}.tt .hero.plain .wrap{padding-top:34px;padding-bottom:34px}}
/* Body */
.tt .prose h2{font-size:clamp(1.5rem,3vw,2.1rem);display:flex;align-items:center;gap:.5em}
.tt .prose h2::before{content:"";flex:none;width:.62em;height:.62em;border-radius:50%;background:radial-gradient(circle at 35% 35%,rgba(255,255,255,.45) 0 18%,transparent 22%),#c23a2b}
.tt .prose h2:nth-of-type(3n+2)::before{background:radial-gradient(circle at 35% 35%,rgba(255,255,255,.45) 0 18%,transparent 22%),#2457a6}
.tt .prose h2:nth-of-type(3n)::before{background:radial-gradient(circle at 35% 35%,rgba(255,255,255,.45) 0 18%,transparent 22%),#b07a43}
.tt .prose h3{font-size:1.28rem;color:#6b4423}
.tt .cards{gap:20px}
.tt .card{background:#fffdf8;border:1px solid #e8d9c2;border-radius:22px;padding:22px 24px;position:relative;overflow:hidden}
.tt .card::before{content:"";position:absolute;left:0;top:0;right:0;height:7px;background:#c23a2b}
.tt .cards>.card:nth-child(3n+2)::before{background:#2457a6}.tt .cards>.card:nth-child(3n)::before{background:#b07a43}
.tt .card h3{margin:.2em 0 .35em;font-size:1.3rem;color:#3a2614}
.tt .prose a.card{color:var(--ink)}
.tt a.card{transition:transform .15s,box-shadow .15s}
.tt a.card:hover{transform:translateY(-3px);box-shadow:0 12px 26px rgba(90,55,25,.14);border-color:#d9c3a3}
.tt .callout{background:#f3e9da;border-left:0;border-radius:18px;padding:16px 22px}
.tt .callout.safe{background:#fbe9e5}
.tt .callout.safe::before{content:"Safety note";display:block;font-family:var(--hf);color:#a32d20;font-size:1.15rem;margin-bottom:.2em}
.tt .table-wrap{background:#fffdf8;border:1px solid #e8d9c2;border-radius:18px}
.tt th{font-family:var(--hf);font-weight:400;background:#6b4423;color:#fff7ea;font-size:1.02rem}
.tt tbody tr:nth-child(even) td{background:#faf3e7}
.tt details{background:#fffdf8;border:1px solid #e8d9c2;border-radius:16px;margin-bottom:.7em}
.tt summary{color:#3a2614}
.tt .steps li::before{background:#2457a6;color:#fff;font-family:var(--hf);font-weight:400;border-radius:50%;box-shadow:inset -3px -3px 0 rgba(0,0,0,.18)}
.tt .checks{list-style:none;padding:0}.tt .checks li{position:relative;padding-left:32px;margin-bottom:.6em}
.tt .checks li::before{content:"";position:absolute;left:2px;top:.3em;width:16px;height:16px;border-radius:50%;background:#fffdf8;border:3px solid #b07a43}
.tt figure.pic{margin:0 0 1.8em}.tt figure.pic img{border-radius:24px;aspect-ratio:16/8;object-fit:cover;width:100%}
.tt figure.pic figcaption{font-size:.9rem;color:var(--muted);margin-top:.6em}
.tt .page{padding-top:36px}
.tt article.prose>:first-child{margin-top:0}
.tt footer.site{background:#3b2717;color:#eadbc4;border-top:0}
.tt footer.site::before{content:"";display:block;height:10px;background:repeating-linear-gradient(90deg,#c23a2b 0 22px,#2457a6 22px 44px,#b07a43 44px 66px);opacity:.9}
.tt footer.site a{color:#f3c58a}
/* Signature: age abacus */
.tt .abacus{margin:0 0 2.2em}
.tt .abacus .frame{border-radius:26px;padding:16px;background:repeating-linear-gradient(90deg,#b9814a 0 4px,#a8713d 4px 7px,#c08a53 7px 13px,#a36b38 13px 16px);box-shadow:inset 0 0 0 2px rgba(60,35,15,.25),0 14px 30px rgba(90,55,25,.16)}
.tt .ab-grid{display:grid;grid-template-columns:minmax(150px,1.25fr) minmax(0,3fr);background:#fffaf1;border-radius:14px;padding:12px 18px 14px;column-gap:16px;box-shadow:inset 0 2px 6px rgba(60,35,15,.25)}
.tt .ab-l{padding:7px 0;line-height:1.2;display:flex;flex-direction:column;justify-content:center;border-bottom:1px dashed #ead9c0}
.tt .ab-l b{font-weight:600;font-size:.95rem}
.tt .ab-l small{color:var(--muted);font-size:.78rem;margin-top:2px}
.tt .ab-h{font-family:var(--hf);font-size:1rem;color:#6b4423;border-bottom:0}
.tt .ab-ages{display:grid;grid-template-columns:repeat(11,1fr);align-items:end;font-family:var(--hf);color:#6b4423;font-size:.95rem;text-align:center}
.tt .ab-ages .dim{opacity:.4}
.tt .rod{display:grid;grid-template-columns:repeat(11,1fr);align-items:center;position:relative;border-bottom:1px dashed #ead9c0}
.tt .rod::before{content:"";position:absolute;left:0;right:0;top:50%;height:4px;margin-top:-2px;border-radius:2px;background:linear-gradient(180deg,#d6d0c6,#9a9286)}
.tt .bd{display:block;position:relative;width:min(84%,58px);height:26px;margin:0 auto;border-radius:50%/50%;background:radial-gradient(ellipse at 34% 30%,rgba(255,255,255,.5) 0 14%,transparent 30%),radial-gradient(ellipse at 50% 120%,rgba(0,0,0,.28),transparent 60%),var(--c)}
.tt .bd.dim{opacity:.32}
.tt .gap{display:block;height:26px}
.tt .abacus figcaption{margin-top:12px;font-size:.92rem;color:var(--muted)}
.tt .abacus figcaption p{margin:0 0 .4em}
.tt .ab-key{display:flex;flex-wrap:wrap;gap:6px 18px;color:#3a2614}
.tt .ab-key span{display:inline-flex;align-items:center;gap:8px}
.tt .ab-key .bd{width:26px;height:16px;margin:0}
@media(min-width:1800px){.tt .bd,.tt .gap{height:32px}.tt .ab-l b{font-size:1.02rem}.tt .ab-grid{padding:16px 26px}}
@media(max-width:600px){.tt .abacus .frame{padding:9px;border-radius:18px}.tt .ab-grid{grid-template-columns:minmax(92px,.9fr) minmax(0,2fr);padding:8px 8px 10px;column-gap:8px}.tt .ab-l small{display:none}.tt .ab-l b{font-size:.8rem}.tt .ab-ages{font-size:.66rem}.tt .bd,.tt .gap{height:15px}.tt .bd{width:88%}.tt .rod::before{height:3px;margin-top:-1.5px}}