/* Steer, Don't Guess · design system "Clear Instrument" (v2, 2026-10-30). Mobile first. */
:root{
  --paper:#F7F8F6; --surface:#FFFFFF; --mist:#EAF1F5; --deep:#173F57; --line:#DDE3E7;
  --ink:#10202E; --text:#2E3B48; --muted:#56646F; --on-deep:#CFE3EE; --on-deep-accent:#9FD3E6;
  --steel:#245B7C; --steel-dark:#173F57; --amber:#F2B233; --amber-dark:#D99A1F;
  --zg:#2F6B55; --zg-bg:#E3F0EA; --zy:#D9A30A; --zy-text:#855C00; --zy-bg:#FBEFCF; --zr:#B4432B; --zr-bg:#F8E2DC;
  --sans:"Inter",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --serif:"Source Serif 4",Georgia,"Times New Roman",serif;
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;
  --r-card:16px; --r-btn:12px; --page:1120px; --read:680px; --gutter:20px;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:76px}
body{margin:0;background:var(--paper);color:var(--text);font:400 17px/1.6 var(--sans);-webkit-font-smoothing:antialiased}
img{max-width:100%;height:auto}
a{color:var(--steel);text-decoration:underline;text-decoration-thickness:1px;text-underline-offset:3px}
a:hover{color:var(--steel-dark)}
:focus-visible{outline:3px solid var(--steel);outline-offset:2px;border-radius:4px}
.skip{position:absolute;left:-999px}.skip:focus{left:8px;top:8px;background:var(--amber);color:var(--ink);padding:10px 14px;z-index:99}
h1,h2,h3,h4{font-family:var(--sans);color:var(--ink);margin:0 0 .5em;letter-spacing:-.01em}
h1{font-size:34px;line-height:40px;font-weight:800;letter-spacing:-.02em}
h2{font-size:26px;line-height:32px;font-weight:700;margin-top:1.8em}
h3{font-size:20px;line-height:28px;font-weight:600;margin-top:1.4em}
p{margin:0 0 1em}
.wrap{max-width:var(--page);margin:0 auto;padding:0 var(--gutter)}
.col{max-width:var(--read)}
.label,.meta{display:block;font:600 13px/1.4 var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--steel);margin:0 0 10px}
.muted{color:var(--muted)}.small{font-size:15px;line-height:1.5}
.lead{font-size:18px;line-height:1.55;color:var(--ink);margin:0 0 1.4em}

/* header + mobile menu */
.top{position:sticky;top:0;z-index:40;background:rgba(247,248,246,.95);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;gap:12px;min-height:60px;padding-right:8px}
.logo{display:flex;align-items:center;min-height:48px;font:800 17px/1.2 var(--sans);color:var(--ink);text-decoration:none}
.logo-sub{display:none}
.menu{position:static;border:0 !important}
.menu>summary{list-style:none;width:48px;height:48px;display:grid;place-items:center;border-radius:var(--r-btn);cursor:pointer;color:var(--ink)}
.menu>summary::-webkit-details-marker{display:none}
.menu>summary .x{display:none}.menu[open]>summary .bars{display:none}.menu[open]>summary .x{display:block}
.menu-panel{position:absolute;left:0;right:0;top:100%;background:var(--paper);border-bottom:1px solid var(--line);padding:4px var(--gutter) 20px;box-shadow:0 12px 24px rgba(16,32,46,.10)}
.menu-panel a{display:flex;align-items:center;min-height:56px;border-bottom:1px solid var(--line);font:600 18px var(--sans);color:var(--ink);text-decoration:none}
.menu-panel a.btn{border:0;margin-top:16px;justify-content:center}
.nav-desk{display:none}

/* buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:52px;padding:0 22px;border-radius:var(--r-btn);
  font:700 17px/1.2 var(--sans);text-decoration:none;text-align:center;border:2px solid transparent;cursor:pointer}
.btn-buy,.btn-amber{background:var(--amber);color:var(--ink)}
.btn-buy:hover,.btn-amber:hover,.btn-buy:active{background:var(--amber-dark);color:var(--ink)}
.btn-line,.btn-teal{border-color:var(--steel);color:var(--steel);background:transparent;font-weight:600}
.btn-line:hover,.btn-teal:hover{background:var(--mist);color:var(--steel-dark)}
.btn-steel{background:var(--steel);color:#fff}.btn-steel:hover{background:var(--steel-dark);color:#fff}
.btn-white{background:#fff;color:var(--deep)}.btn-white:hover{background:var(--mist);color:var(--deep)}
.btn-sm{min-height:44px;padding:0 16px;font-size:16px}
.btn-row{display:flex;flex-direction:column;gap:12px;margin:20px 0 10px}
.btn-row .btn{width:100%}
.textlink{display:inline-flex;align-items:center;min-height:48px;font-weight:600}
.markets{font-size:15px;line-height:1.5;color:var(--muted);text-align:center;margin:6px 0 0}
.markets a{white-space:nowrap}

/* hero */
.hero{padding:32px 0 48px}
.hero-grid{display:flex;flex-direction:column;gap:20px}
.hero h1{font-size:40px;line-height:44px;margin:0}
.hero .sub{font-size:18px;line-height:1.5;color:var(--ink);margin:0}
.hero .hook{font:400 19px/1.6 var(--serif);margin:0}
.hero .hook strong{font-family:var(--sans);font-weight:700;color:var(--ink)}
.cover{align-self:center;width:210px;margin:8px 0}
.cover img{display:block;width:100%;height:auto;border-radius:6px;box-shadow:0 22px 44px rgba(16,32,46,.25)}
.hero-text{display:contents}
.hero-text>*{order:5}
.hero-text>.label,.hero-text>h1,.hero-text>.sub{order:1}
.cover{order:3}
.hero-text>.hook{order:2}

/* proof band */
.band{background:var(--deep);color:#fff}
.band h2{color:#fff;margin-top:0}
.band .label{color:var(--on-deep-accent)}
.band a{color:#fff}
.band-in{padding:48px 0}
.proof{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;margin:20px 0 16px}
.tile{padding:16px;background:rgba(255,255,255,.08);border-radius:var(--r-card)}
.tile:first-child{grid-column:1/-1;padding:20px}
.num{display:block;font:800 30px/1.1 var(--sans);letter-spacing:-.02em;color:#fff;font-variant-numeric:tabular-nums}
.tile:first-child .num{font-size:44px}
.tile p{margin:6px 0 0;font-size:14px;line-height:1.45;color:var(--on-deep)}
.band .fine{font-size:14px;line-height:1.5;color:var(--on-deep);margin:0}

/* sections */
.sec{padding:56px 0}
.sec-mist{background:var(--mist)}
.sec-white{background:var(--surface);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.sec h2:first-child,.sec .label+h2{margin-top:0}

/* home body (markdown) */
.home-body h2{margin-top:2.2em}
.home-body>p,.home-body li{font-family:var(--serif);font-size:18px;line-height:1.65}
.home-body ul{list-style:none;padding:0;margin:0 0 1.4em;counter-reset:n}
.home-body ul li{counter-increment:n;position:relative;padding:14px 0 14px 46px;border-bottom:1px solid var(--line);font-family:var(--sans);font-size:16px;line-height:1.5}
.home-body ul li:last-child{border-bottom:0}
.home-body ul li::before{content:counter(n);position:absolute;left:0;top:12px;width:32px;height:32px;border-radius:999px;background:var(--mist);color:var(--steel);font-weight:700;display:grid;place-items:center;font-size:15px}
.home-body ul li strong{color:var(--ink)}
.chapters{display:flex;flex-direction:column;font-size:16px;line-height:1.5;margin:0 0 1.4em}
.chapters div{padding:10px 0;border-bottom:1px solid var(--line)}
.chapters div:empty{display:none}
.chapters b{color:var(--ink)}
.chapters .part{border-bottom:0;padding:24px 0 6px;font:700 13px/1.4 var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--steel)}
.chapters .part:first-child{padding-top:4px}

/* pricing */
.prices{display:flex;flex-direction:column;gap:10px}
.price-main{display:flex;flex-direction:column;gap:10px;padding:20px;background:var(--surface);border:2px solid var(--steel);border-radius:var(--r-card)}
.price-main .pill{align-self:flex-start}
.price-head{display:flex;justify-content:space-between;align-items:baseline;gap:12px}
.price-head b{font-size:19px;color:var(--ink)}
.price{font:800 30px/1 var(--sans);color:var(--ink);font-variant-numeric:tabular-nums}
.price-row{display:flex;justify-content:space-between;align-items:center;gap:12px;min-height:64px;padding:8px 8px 8px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-btn)}
.price-row b{color:var(--ink)}
.price-row .small{display:block;color:var(--muted)}
.price-row .end{display:flex;align-items:center;gap:6px}
.price-row .end a{display:inline-flex;align-items:center;min-height:48px;padding:0 8px;font-weight:600}
.pill{display:inline-flex;align-items:center;padding:4px 10px;border-radius:999px;background:var(--mist);color:var(--steel);font:700 13px var(--sans)}

/* author strip */
.author-strip{display:flex;gap:16px;align-items:center}
.author-strip img{width:72px;height:72px;border-radius:999px;object-fit:cover;flex:0 0 72px}
.author-strip b{display:block;color:var(--ink)}

/* blocks used inside articles */
.def{background:var(--mist);border-radius:var(--r-card);padding:18px;margin:1.6em 0;font-family:var(--sans);font-size:17px;line-height:1.55;color:var(--ink)}
.def strong:first-child{display:block;font:700 13px/1.4 var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--steel);margin-bottom:6px}
.redline{background:var(--zr-bg);border-radius:var(--r-card);padding:18px;margin:1.6em 0;font-family:var(--sans)}
.answer{background:var(--mist);border-radius:var(--r-card);padding:18px;margin:0 0 20px}
.answer .label{margin-bottom:8px}
.answer p{margin:0;font:400 17px/1.55 var(--sans);color:var(--ink)}
.takeaways{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-card);padding:20px;margin:1.8em 0;font-family:var(--sans)}
.takeaways h2,.takeaways h3{margin:0 0 10px;font-size:19px;line-height:1.3}
.takeaways ul{list-style:none;padding:0;margin:0}
.takeaways li{position:relative;padding-left:30px;margin:10px 0;font-size:16px;line-height:1.5}
.takeaways li::before{content:"";position:absolute;left:2px;top:4px;width:16px;height:9px;border-left:2.5px solid var(--zg);border-bottom:2.5px solid var(--zg);transform:rotate(-45deg)}
details{border-bottom:1px solid var(--line)}
details:first-of-type{border-top:1px solid var(--line)}
summary{list-style:none;display:flex;justify-content:space-between;align-items:center;gap:12px;min-height:64px;padding:8px 0;font:600 17px/1.4 var(--sans);color:var(--ink);cursor:pointer}
summary::-webkit-details-marker{display:none}
summary::after{content:"";flex:0 0 10px;height:10px;border-right:2px solid var(--steel);border-bottom:2px solid var(--steel);transform:rotate(45deg) translate(-3px,-3px);transition:transform .15s}
details[open]>summary::after{transform:rotate(-135deg) translate(-2px,-2px)}
details>p{margin:0 0 16px;font-size:16px;line-height:1.6}
.menu summary::after{display:none}

/* tables: scroll inside their own box */
.tbl{overflow-x:auto;-webkit-overflow-scrolling:touch;border:1px solid var(--line);border-radius:var(--r-btn);background:var(--surface);margin:1.4em 0}
table{border-collapse:collapse;width:100%;font:400 15px/1.45 var(--sans)}
.tbl table{min-width:480px;margin:0}
th{text-align:left;padding:12px 14px;background:var(--paper);color:var(--ink);font-weight:700;border-bottom:1px solid var(--line)}
td{padding:12px 14px;border-top:1px solid var(--line);vertical-align:top}
tr:first-child td{border-top:0}
td.n,th.n{text-align:right;font-variant-numeric:tabular-nums}
.zr{color:var(--zr);font-weight:600}.zy{color:var(--zy-text);font-weight:600}.zg{color:var(--zg);font-weight:600}
code{font-family:var(--mono);font-size:.9em;background:var(--mist);padding:1px 5px;border-radius:4px}
pre{font-family:var(--mono);font-size:14px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-btn);padding:14px 16px;overflow:auto}
pre code{background:none;padding:0}
blockquote{margin:1.4em 0;padding:0;font:400 21px/1.5 var(--serif);color:var(--ink)}
hr{border:0;border-top:1px solid var(--line);margin:2em 0}

/* article page */
.article{padding-top:16px}
.crumb{display:inline-flex;align-items:center;gap:6px;min-height:44px;font-weight:600;text-decoration:none;font-size:15px}
.article h1{font-size:32px;line-height:38px;margin:4px 0 16px}
.byline{display:flex;gap:12px;align-items:center;margin:0 0 20px;font-size:14px;line-height:1.4}
.byline img.ava{width:40px;height:40px;border-radius:999px;object-fit:cover;display:block}
.byline b{display:block;color:var(--ink)}
.byline span{color:var(--muted)}
.toc{background:var(--surface);border:1px solid var(--line) !important;border-radius:var(--r-btn);padding:0 16px;margin:0 0 24px}
.toc summary{min-height:52px;font-size:16px}
.toc ol{margin:0 0 14px;padding-left:20px;font-size:16px;line-height:1.5}
.toc li{margin:8px 0}
.prose{font:400 19px/1.63 var(--serif)}
.prose h2{font-family:var(--sans);font-size:24px;line-height:30px;margin-top:1.8em}
.prose h3{font-family:var(--sans);font-size:20px;line-height:28px}
.prose ul,.prose ol{padding-left:1.2em}.prose li{margin:.4em 0}
.prose li strong,.prose p strong{color:var(--ink)}
.inline-buy{display:flex;gap:14px;align-items:center;padding:16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-card);margin:2em 0}
.inline-buy img{width:64px;height:auto;border-radius:4px;box-shadow:0 8px 18px rgba(16,32,46,.2);flex:0 0 64px}
.inline-buy p{margin:0 0 8px;font-size:15px;line-height:1.45;color:var(--ink)}
.cta-deep{background:var(--deep);color:#fff;border-radius:var(--r-card);padding:24px 20px;margin:2em 0}
.cta-deep h2{color:#fff;margin:0 0 8px;font-size:22px;line-height:1.3}
.cta-deep p{color:var(--on-deep);margin:0 0 16px;font-size:16px;line-height:1.5}
.cta-deep .btn-row{margin:0}
.note{font-size:14px;line-height:1.5;color:var(--muted);margin-top:2em}

/* cards */
.cards{display:flex;flex-direction:column;gap:12px;margin:16px 0 24px}
.card{display:flex;flex-direction:column;gap:6px;padding:18px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-btn);color:var(--text);text-decoration:none}
.card:hover{border-color:var(--steel);color:var(--text)}
.card .meta{margin:0;font-size:12px;color:var(--muted)}
.card h3{margin:0;font-size:17px;line-height:1.4;color:var(--ink)}
.card p{margin:0;font-size:15px;line-height:1.5;color:var(--muted)}

/* page header */
.page-head{padding:32px 0 8px}
.page-head h1{margin:0 0 14px}
.author-photo{margin:0 0 24px}
.author-photo img{width:100%;max-height:440px;object-fit:cover;object-position:top;border-radius:var(--r-card);display:block}
.glossary p{margin:0;padding:12px 0;border-bottom:1px solid var(--line);font-family:var(--sans);font-size:16px;line-height:1.5}
.glossary strong{color:var(--ink)}

/* book text (free sample) */
.bookbody figure{margin:2em 0}
.bookbody figure img{width:100%;height:auto;background:#fff;border-radius:var(--r-btn);padding:10px;border:1px solid var(--line)}
.bookbody figcaption{font:400 14px/1.4 var(--sans);color:var(--muted);margin-top:8px}
.bookbody .basic,.bookbody .practical,.bookbody .advanced,.bookbody .example{background:var(--surface);border:1px solid var(--line);border-radius:var(--r-card);padding:16px 18px 6px;margin:1.6em 0}
.bookbody .basic::before,.bookbody .practical::before,.bookbody .advanced::before,.bookbody .example::before{display:block;font:700 13px var(--sans);letter-spacing:.08em;text-transform:uppercase;margin-bottom:8px}
.bookbody .basic::before{content:"Basic level";color:var(--zg)}.bookbody .practical::before{content:"Practical level";color:var(--zy-text)}.bookbody .advanced::before{content:"Advanced level";color:var(--zr)}
.bookbody .example::before{content:attr(title);color:var(--steel)}
.bookbody .signature{text-align:right;font-style:italic;color:var(--muted)}
.bookbody math{font-size:1.05em}.bookbody math[display="block"]{display:block;overflow-x:auto;margin:1em 0}
.bookbody table{display:block;overflow-x:auto}

/* footer */
.floor{background:var(--deep);color:var(--on-deep);margin-top:56px;padding-bottom:calc(88px + env(safe-area-inset-bottom))}
.foot{padding:40px var(--gutter) 24px;display:flex;flex-direction:column;gap:24px}
.foot-title{font:700 17px/1.35 var(--sans);color:#fff;margin:0 0 6px}
.foot p{font-size:15px;line-height:1.5}
.foot-cols{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:4px 16px}
.foot-cols>div{display:contents}
.foot-h{display:none}
.foot a{display:flex;align-items:center;min-height:44px;color:#fff;text-decoration:none;font-size:15px}
.foot a:hover{text-decoration:underline}
.copyright{font-size:13px;margin:0}

/* sticky buy bar (phones) */
.buybar{position:fixed;left:12px;right:12px;bottom:max(12px,env(safe-area-inset-bottom));z-index:30;display:flex;align-items:center;justify-content:space-between;gap:12px;
  padding:10px 10px 10px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-card);box-shadow:0 -6px 24px rgba(16,32,46,.12);
  transform:translateY(0);transition:transform .2s ease,opacity .2s ease}
.buybar.is-hidden{transform:translateY(140%);opacity:0;pointer-events:none}
.buybar b{display:block;color:var(--ink);font-size:15px;line-height:1.3}
.buybar span{display:block;color:var(--muted);font-size:13px;line-height:1.3}
.buybar .btn{min-height:48px;padding:0 18px;font-size:16px}

/* ≥ 640px */
@media (min-width:640px){
  .btn-row{flex-direction:row;flex-wrap:wrap;align-items:center}
  .btn-row .btn{width:auto}
  .markets{text-align:left}
  .cover{width:240px}
  .cards{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}
}
/* ≥ 768px: desktop navigation, no sticky bar */
@media (min-width:768px){
  :root{--gutter:24px}
  .floor{padding-bottom:0}
  .buybar{display:none}
  .nav{min-height:72px;padding-right:0}
  .menu{display:none}
  .nav-desk{display:flex;align-items:center;gap:4px}
  .nav-desk a{display:inline-flex;align-items:center;min-height:44px;padding:0 12px;color:var(--ink);text-decoration:none;font-weight:500;font-size:16px;border-radius:10px}
  .nav-desk a:hover{background:var(--mist)}
  .nav-desk a.btn{margin-left:8px;background:var(--amber);font-weight:700}
  .nav-desk a.btn:hover{background:var(--amber-dark)}
  h1{font-size:44px;line-height:50px}
  h2{font-size:32px;line-height:38px}
  .sec{padding:80px 0}
  .band-in{padding:72px 0}
  .proof{grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
  .tile,.tile:first-child{grid-column:auto;padding:28px}
  .num,.tile:first-child .num{font-size:52px}
  .tile p{font-size:16px}
  .prices{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}
  .price-main{grid-row:span 3}
  .foot{flex-direction:row;flex-wrap:wrap;justify-content:space-between;padding:56px var(--gutter) 32px}
  .foot>div:first-child{flex:1 1 360px}
  .foot-cols{grid-template-columns:repeat(3,auto);gap:4px 32px}
  .copyright{flex:1 1 100%}
  .article h1{font-size:44px;line-height:50px}
  .page-head{padding:56px 0 8px}
  .author-photo{max-width:380px}
}
/* ≥ 1024px: two-column hero */
@media (min-width:1024px){
  h1{font-size:56px;line-height:60px}
  .hero{padding:72px 0 96px}
  .hero-grid{flex-direction:row;align-items:center;gap:56px}
  .hero-text{display:flex;flex-direction:column;gap:22px;flex:1 1 0;min-width:0}
  .hero h1{font-size:60px;line-height:64px}
  .hero .sub{font-size:21px}
  .hero .hook{font-size:20px;max-width:34em}
  .cover{order:2;width:300px;flex:0 0 300px;margin:0}
  .cards{grid-template-columns:repeat(3,minmax(0,1fr))}
  .prices{grid-template-columns:repeat(4,minmax(0,1fr))}
  .price-main{grid-row:auto}
}
@media (prefers-reduced-motion:reduce){html{scroll-behavior:auto}.buybar{transition:none}}
@media print{.top,.buybar,.floor{display:none}body{padding:0}}

/* 2026-10-30 conversion pass: proof bars, CTA hierarchy, scannable list */
.band-lead{color:var(--on-deep);font-size:17px;line-height:1.55;margin:0 0 20px;max-width:40em}
.bars{display:grid;gap:20px;margin:0 0 20px}
.bar-group{padding:16px;background:rgba(255,255,255,.06);border-radius:var(--r-card)}
.bar-q{margin:0 0 10px;font:700 13px/1.4 var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--on-deep-accent)}
.bar-row{display:grid;grid-template-columns:124px 1fr 60px;align-items:center;gap:10px;padding:6px 0;font-size:14px;color:var(--on-deep)}
.bar-row b{color:#fff;text-align:right;font-size:16px}
.bar{display:block;height:12px;background:rgba(255,255,255,.1);border-radius:999px;overflow:hidden}
.bar i{display:block;height:100%;min-width:4px;background:rgba(255,255,255,.4);border-radius:999px}
.bar-row.good i{background:var(--on-deep-accent)}
.bar-row.good .bar-name{color:#fff;font-weight:600}
.proof-2{grid-template-columns:repeat(2,minmax(0,1fr))}
.proof-2 .tile:first-child{grid-column:auto;padding:16px}
.proof-2 .tile:first-child .num{font-size:30px}
.btn-lg{min-height:56px;font-size:17px}
.free-link{font-size:15px}
.hero .markets{text-align:left}
.home-body ul li strong{display:block;font-size:17px;margin-bottom:2px}
.home-body ul li em{font-style:normal}
.price-lead{font:400 19px/1.5 var(--serif);color:var(--text);margin:-4px 0 18px}
.included{margin:18px 0 6px;padding:14px 16px;background:var(--surface);border:1px solid var(--line);border-radius:var(--r-card);font-size:15px;line-height:1.55}
.included b{color:var(--ink)}
.author-bio{font:400 17px/1.6 var(--serif);margin:14px 0 0}
@media (min-width:768px){
  .bars{grid-template-columns:repeat(2,minmax(0,1fr));gap:20px}
  .bar-row{grid-template-columns:130px 1fr 72px}
  .proof-2 .tile:first-child,.proof-2 .tile{padding:24px}
  .proof-2 .num,.proof-2 .tile:first-child .num{font-size:44px}
}