/* Sparky Papers v2 (brand system 2026-10-16). Lexend for words, IBM Plex Mono for every number, formula and reading.
   Spark (#e9b44c) is never used for text: only dots, rules and focus rings on dark ground. */
@font-face{font-family:Lexend;src:url(/assets/fonts/Lexend-Regular.26cb5265.woff2) format("woff2");font-weight:400;font-display:swap}
@font-face{font-family:Lexend;src:url(/assets/fonts/Lexend-SemiBold.a116b6ef.woff2) format("woff2");font-weight:600;font-display:swap}
@font-face{font-family:Lexend;src:url(/assets/fonts/Lexend-Bold.e480f101.woff2) format("woff2");font-weight:700;font-display:swap}
@font-face{font-family:"IBM Plex Mono";src:url(/assets/fonts/IBMPlexMono-Regular.f5059121.woff2) format("woff2");font-weight:400;font-display:swap}
@font-face{font-family:"IBM Plex Mono";src:url(/assets/fonts/IBMPlexMono-Bold.7e44bbb3.woff2) format("woff2");font-weight:700;font-display:swap}
:root{--pine:#0e5a4a;--pine-dark:#0a4236;--ink:#1c1f1d;--brick:#b8402a;--brick-dark:#8e2f1e;--spark:#e9b44c;
  --paper:#f5f0e4;--grid:#ddd5c1;--gridline:#e6dfcf;--card:#fffdf8;--body:#3e4440;--muted:#5c615d;
  --pine-tint:#e3eeea;--pine-pale:#cde3dc;--brick-tint:#f3e2dd;--stone-tint:#ece6d8;--dark-text:#d9d3c4;--dark-line:#3a3f3c;
  --mono:"IBM Plex Mono",Lexend,ui-monospace,Menlo,monospace;--sans:Lexend,system-ui,-apple-system,"Segoe UI",sans-serif}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);font-size:17px;line-height:1.6}
img{max-width:100%;height:auto}
button,input,select,textarea{font-family:inherit}
a{color:var(--pine);text-underline-offset:3px;text-decoration-thickness:1.5px}
a:hover{color:var(--pine-dark)}
:focus-visible{outline:3px solid var(--brick);outline-offset:3px;border-radius:4px}
.dark :focus-visible,.bundle-band :focus-visible,.tile.tool:focus-visible{outline-color:var(--spark)}
.skip{position:absolute;left:-999px;top:0;background:var(--ink);color:var(--paper);padding:12px 16px;z-index:10;font-weight:600}
.skip:focus{left:8px;top:8px}
.wrap{max-width:1200px;margin:0 auto;padding:0 16px}
.vh{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap;border:0}
.mono,.num{font-family:var(--mono)}
.num{font-variant-numeric:tabular-nums;white-space:nowrap}
.sq{background-color:var(--paper);background-image:linear-gradient(var(--gridline) 1px,transparent 1px),linear-gradient(90deg,var(--gridline) 1px,transparent 1px);background-size:24px 24px}

/* header */
.site-head{border-bottom:1px solid var(--grid);background:var(--paper)}
.site-head .wrap{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:4px 16px;padding-top:10px;padding-bottom:10px}
.logo{display:inline-flex;align-items:center;gap:10px;text-decoration:none;color:var(--ink);min-height:48px}
.logo svg,.foot-brand svg{flex:none;display:block}
.logo span{font-size:21px;font-weight:700;letter-spacing:-.01em}
.logo .p,.foot-brand .p{color:var(--pine)}
.logo:hover{color:var(--ink)}
.site-nav ul{list-style:none;margin:0;padding:0;display:flex;flex-wrap:wrap;gap:0 18px}
.site-nav a{display:inline-flex;align-items:center;min-height:44px;color:var(--ink);text-decoration:none;font-size:15.5px}
.site-nav a:hover,.site-nav a[aria-current=page]{color:var(--pine);text-decoration:underline;text-decoration-thickness:2px}

/* type */
h1{font-size:clamp(34px,8.4vw,56px);line-height:1.05;letter-spacing:-.025em;margin:0 0 18px;font-weight:700}
h2{font-size:clamp(27px,5.4vw,38px);line-height:1.15;letter-spacing:-.02em;margin:0 0 12px;font-weight:700}
h3{font-size:19px;line-height:1.3;margin:0 0 8px;font-weight:700}
.kick{font-family:var(--mono);font-size:13.5px;letter-spacing:.12em;text-transform:uppercase;color:var(--brick);margin:0 0 12px;line-height:1.45}
.lead{font-size:18.5px;line-height:1.6;color:var(--body);max-width:36em;margin:0 0 6px}
.lead strong{color:var(--ink)}
p{margin:0 0 14px}
.small{font-size:14.5px;color:var(--muted)}
.cred{display:flex;gap:10px;align-items:flex-start;font-size:15px;color:var(--body);margin:20px 0 0}
.cred svg{flex:none;margin-top:3px}

/* sections */
.sec{padding-top:52px;padding-bottom:52px}
.sec-head{max-width:44em;margin-bottom:26px}
.sec-head p:last-child{margin-bottom:0}
.sec-head .lead{max-width:none}
.alt{background:var(--card);border-top:1px solid var(--grid);border-bottom:1px solid var(--grid)}
.hero{border-bottom:1px solid var(--grid);padding:44px 0 52px}
.hero-grid{display:grid;gap:36px;align-items:center}
.hero-grid>*,.sampler>*,.two>*,.product-top>*,.calc-wrap>*{min-width:0}
.hero.slim{padding:36px 0 30px}
.hero.slim h1{font-size:clamp(32px,7vw,48px)}
.dark{background:var(--ink);color:var(--paper)}
.dark .kick{color:var(--pine-pale)}
.dark p{color:var(--dark-text)}
.dark a{color:var(--paper)}

/* buttons, pills, notices */
.btns{display:flex;gap:12px;flex-wrap:wrap;margin:24px 0 8px}
.btn{display:inline-flex;align-items:center;justify-content:center;min-height:52px;padding:0 24px;border-radius:10px;background:var(--pine);color:#fff;font-weight:600;font-size:16.5px;line-height:1.25;text-decoration:none;text-align:center;border:2px solid var(--pine)}
.btn:hover{background:var(--pine-dark);border-color:var(--pine-dark);color:#fff}
.btn.alt,.btn.ghost{background:transparent;color:var(--ink);border-color:var(--ink)}
.btn.alt:hover,.btn.ghost:hover{background:var(--ink);color:var(--paper)}
.btn.paper{background:var(--paper);border-color:var(--paper);color:var(--pine);font-weight:700}
.btn.paper:hover{background:#fff;border-color:#fff;color:var(--pine-dark)}
.dark .btn.paper{color:var(--ink)}
.pills{list-style:none;display:flex;flex-wrap:wrap;gap:8px;margin:0 0 16px;padding:0}
.pill{font-family:var(--mono);font-size:13px;line-height:1.3;padding:6px 10px;border-radius:999px;background:var(--stone-tint);color:var(--body)}
.pill.pine{background:var(--pine-tint);color:var(--pine)}
.pill.brick{background:var(--brick-tint);color:var(--brick-dark)}
.soon{display:flex;gap:10px;align-items:flex-start;padding:12px 14px;border-radius:10px;background:var(--pine-tint);border:1px solid var(--pine-pale);font-size:15px;line-height:1.45;color:var(--ink);margin:18px 0 10px;max-width:40em}
.soon svg{flex:none;margin-top:1px}
.price{font-weight:700;font-size:28px;color:var(--ink);margin:14px 0 0}
.price small{font-size:14.5px;font-weight:400;color:var(--muted);margin-left:6px}
.note{background:var(--card);border:1px solid var(--grid);border-left:4px solid var(--pine);border-radius:10px;padding:14px 16px;margin:18px 0;font-size:15px;color:var(--body)}
.notice{background:var(--brick-tint);border:1px solid #e8c6bd;border-radius:10px;padding:14px 16px;margin:18px 0;font-size:15px;color:var(--ink)}
.notice strong{color:var(--brick-dark)}

/* worked-answer card (home hero) */
.worked{margin:0;width:100%;max-width:460px;justify-self:center;background:var(--card);border:1px solid var(--grid);border-radius:16px;box-shadow:0 18px 40px rgba(28,31,29,.10);padding:18px;display:flex;flex-direction:column;gap:14px}
.worked .top{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;font-family:var(--mono);font-size:13px}
.worked .top .q{color:var(--brick);letter-spacing:.08em}
.worked .top .w{color:var(--muted)}
.worked .ask{font-size:16px;line-height:1.55;margin:0}
.readout{font-family:var(--mono);font-size:15px;line-height:1.85;background:var(--ink);color:var(--paper);border-radius:10px;padding:14px 16px;margin:0;overflow-x:auto}
.readout span{display:block;padding-left:2ch;text-indent:-2ch}
.readout .cont{padding-left:4ch}
.verdict-pill{display:flex;flex-wrap:wrap;align-items:center;gap:10px;padding:10px 12px;border-radius:10px;background:var(--brick-tint);color:var(--brick-dark);font-weight:600;font-size:15px;margin:0}
.verdict-pill .num{font-family:var(--mono)}
.worked figcaption{font-size:13.5px;color:var(--muted)}

/* book cards */
.cards{display:grid;gap:18px;grid-template-columns:1fr}
.card{background:var(--card);border:1px solid var(--grid);border-radius:14px;padding:18px;display:flex;flex-direction:column;gap:10px}
.card .cover{display:block;line-height:0;border-radius:6px;overflow:hidden;box-shadow:0 10px 22px rgba(28,31,29,.14);background:var(--stone-tint)}
.card .cover img{display:block;width:100%;height:auto}
.card h3{margin:6px 0 0;font-size:18px}
.card h3 a{color:var(--ink);text-decoration:none}
.card h3 a:hover{color:var(--pine);text-decoration:underline}
.card p{margin:0;font-size:15px;line-height:1.55;color:var(--body)}
.card .meta{font-family:var(--mono);font-size:13px;color:var(--muted)}
.card .foot{margin-top:auto;display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;padding-top:6px}
.card .foot .price{font-size:22px;margin:0}
.card .foot a{font-size:15px;font-weight:600;display:inline-flex;align-items:center;min-height:44px}
.card .btn{min-height:48px;font-size:15px}
.bundle-band{margin-top:22px;display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:18px;background:var(--pine);color:#fff;border-radius:16px;padding:24px}
.bundle-band .kick{color:var(--pine-pale);margin-bottom:6px}
.bundle-band h3{font-size:clamp(22px,4.6vw,26px);margin:0 0 6px;color:#fff}
.bundle-band p{color:var(--pine-pale);margin:0}
.bundle-band .btns{margin:0}

/* principles row */
.rules4{list-style:none;margin:0;padding:0;display:grid;gap:22px;grid-template-columns:1fr}
.rules4 li{border-top:3px solid var(--pine);padding-top:14px;font-size:15.5px;line-height:1.55;color:var(--body)}

/* sampler */
.sampler{display:grid;gap:34px;align-items:center}
.sampler h2{color:var(--paper)}
.sampler-act{display:flex;align-items:center;gap:18px;flex-wrap:wrap;margin-top:22px}
.sampler-act .thumb{display:block;line-height:0;width:104px;flex:none;border-radius:6px;overflow:hidden;box-shadow:0 10px 24px rgba(0,0,0,.4)}
.sampler-act .thumb img{display:block;width:100%;height:auto}
.topics{list-style:none;margin:0;padding:0;display:grid;gap:10px;grid-template-columns:1fr;counter-reset:t;font-size:15px}
.topics li{counter-increment:t;border:1px solid var(--dark-line);border-radius:10px;padding:12px 14px;display:flex;gap:12px;color:var(--paper);line-height:1.4}
.topics li:before{content:counter(t,decimal-leading-zero);font-family:var(--mono);color:var(--pine-pale);flex:none}

/* learn tiles */
.tiles{list-style:none;margin:0;padding:0;display:grid;gap:16px;grid-template-columns:1fr}
.tile{height:100%;text-decoration:none;color:var(--ink);background:var(--card);border:1px solid var(--grid);border-radius:14px;padding:20px;display:flex;flex-direction:column;gap:8px}
.tile:hover{border-color:var(--pine);color:var(--ink)}
.tile .tag{font-family:var(--mono);font-size:12.5px;letter-spacing:.08em;text-transform:uppercase;color:var(--brick)}
.tile .t{font-size:18px;font-weight:700;line-height:1.3}
.tile:hover .t{text-decoration:underline}
.tile .d{font-size:15px;line-height:1.5;color:var(--body)}
.tile.tool{background:var(--pine);border-color:var(--pine);color:#fff}
.tile.tool .tag{color:var(--pine-pale)}
.tile.tool .d{color:var(--pine-tint)}

/* faq */
.faq{display:grid;gap:10px;max-width:52em}
details{background:var(--card);border:1px solid var(--grid);border-radius:12px;padding:0 18px}
summary{font-weight:600;cursor:pointer;min-height:52px;display:flex;align-items:center;padding:12px 0;list-style-position:inside}
details[open] summary{border-bottom:1px solid var(--grid)}
details p{margin:12px 0 16px;color:var(--body)}

/* product pages */
.product-top{display:grid;gap:30px;align-items:start}
.cover-big{display:block;line-height:0;max-width:240px;border-radius:8px;overflow:hidden;box-shadow:0 18px 40px rgba(28,31,29,.18);background:var(--card)}
.cover-big img{display:block;width:100%;height:auto}
.two{display:grid;gap:30px;align-items:start}
ul.tick{list-style:none;padding:0;margin:0}
ul.tick li{padding:9px 0 9px 32px;position:relative;border-bottom:1px solid var(--grid);color:var(--body)}
ul.tick li:last-child{border-bottom:0}
ul.tick li:before{content:"";position:absolute;left:2px;top:13px;width:18px;height:18px;border-radius:4px;background:var(--pine)}
ul.tick li:after{content:"";position:absolute;left:7px;top:16px;width:8px;height:5px;border-left:2.5px solid #fff;border-bottom:2.5px solid #fff;transform:rotate(-45deg)}
.panel{background:var(--card);border:1px solid var(--grid);border-radius:14px;padding:20px}
.facts{display:grid;grid-template-columns:auto 1fr;gap:8px 16px;margin:0}
.facts dt{font-family:var(--mono);font-size:13px;letter-spacing:.06em;text-transform:uppercase;color:var(--brick);padding-top:3px}
.facts dd{margin:0;color:var(--body)}
ol.toc{list-style:none;margin:0;padding:0;counter-reset:c;display:grid;gap:8px;grid-template-columns:1fr}
ol.toc li{counter-increment:c;background:var(--card);border:1px solid var(--grid);border-radius:10px;padding:10px 14px;display:flex;gap:12px;line-height:1.4}
ol.toc li:before{content:counter(c,decimal-leading-zero);font-family:var(--mono);color:var(--brick);flex:none}
.tbl-wrap{overflow-x:auto;margin-top:8px}
table.cov{border-collapse:collapse;width:100%;min-width:420px;background:var(--card);font-size:15px;border:1px solid var(--grid)}
table.cov caption{text-align:left;padding:0 0 8px}
table.cov th,table.cov td{border-bottom:1px solid var(--grid);padding:8px 10px;text-align:left}
table.cov td{text-align:center;font-family:var(--mono);font-variant-numeric:tabular-nums}
table.cov thead th{background:var(--stone-tint);font-weight:600}
table.cov tr:last-child th,table.cov tr:last-child td{font-weight:700;border-bottom:0}
.samples{display:grid;gap:18px;grid-template-columns:1fr}
.samples figure{margin:0;background:var(--card);border:1px solid var(--grid);border-radius:12px;padding:12px}
.samples figure a{display:block;line-height:0;border-radius:4px;overflow:hidden;border:1px solid var(--grid)}
.samples img{display:block;width:100%;height:auto}
.samples figcaption{font-size:14px;color:var(--muted);padding-top:10px;line-height:1.45}
.links{list-style:none;margin:0;padding:0;display:grid;gap:10px;grid-template-columns:1fr}
.links a{display:flex;align-items:center;min-height:52px;padding:10px 16px;background:var(--card);border:1px solid var(--grid);border-radius:10px;font-weight:600;text-decoration:none}
.links a:hover{border-color:var(--pine);text-decoration:underline}

/* articles (learn, about, contact, terms, privacy) */
.article{max-width:46em}
.article h2{font-size:clamp(23px,4.4vw,28px);margin-top:36px}
.article h3{margin-top:24px}
.article ul,.article ol{padding-left:24px}
.article ul.tick{padding-left:0}
.article>h2:first-child,.article>.post>h2:first-child{margin-top:0}
.article li{margin:4px 0;color:var(--body)}
.article p{color:var(--body)}
.article p strong,.article li strong{color:var(--ink)}
.article blockquote{margin:18px 0;padding:14px 16px;background:var(--card);border:1px solid var(--grid);border-left:4px solid var(--pine);border-radius:10px;font-size:15px}
.article blockquote p{margin:0}
.post{overflow-wrap:anywhere}
.post ol{list-style:none;counter-reset:s;font-family:var(--mono);font-size:15px;line-height:1.75;background:var(--ink);color:var(--paper);border-radius:10px;padding:14px 16px;margin:6px 0 18px;overflow-wrap:normal}
.post ol li{color:var(--paper);margin:2px 0;padding-left:0}
.post ol strong{color:#fff}
.post .src{font-family:var(--mono);font-size:12.5px;color:var(--muted)}
.post ul.sources{font-size:15px}
.related{margin-top:34px;padding:18px 20px;background:var(--card);border:1px solid var(--grid);border-radius:14px}
.related p{margin:6px 0}

/* calculator */
.calc-wrap{display:grid;gap:30px;align-items:start}
.calc{background:var(--card);border:1px solid var(--grid);border-radius:16px;padding:20px;box-shadow:0 18px 40px rgba(28,31,29,.08)}
.calc fieldset{border:0;padding:0;margin:0 0 18px;min-width:0}
.calc legend{font-weight:700;font-size:18px;margin-bottom:10px;padding:0}
.calc fieldset fieldset legend{font-size:16px;font-weight:600}
.field{margin:0 0 16px}
.field label{display:block;font-weight:600;margin-bottom:4px}
.field .hint{display:block;font-size:14px;color:var(--muted);margin-bottom:6px;line-height:1.45}
.field input[type=text]{font-family:var(--mono);font-size:18px;width:100%;max-width:240px;min-height:48px;padding:10px 12px;border:2px solid var(--ink);border-radius:10px;background:#fff;color:var(--ink)}
.field input[aria-invalid=true]{border-color:var(--brick);background:var(--brick-tint)}
.radio{display:flex;gap:12px;align-items:flex-start;margin:8px 0;min-height:32px;color:var(--body)}
.radio input{width:22px;height:22px;margin-top:2px;flex:none;accent-color:var(--pine)}
.err{color:var(--brick-dark);font-weight:600;font-size:15px;margin:6px 0 0}
.calc .btns{margin:4px 0 0}
.out{margin-top:20px}
.out:empty{display:none}
.out h3{margin:16px 0 8px}
.out h3:first-child{margin-top:0}
.out ol{list-style:none;margin:6px 0 10px;padding:14px 16px;font-family:var(--mono);font-size:15px;line-height:1.75;background:var(--ink);color:var(--paper);border-radius:10px}
.out li{margin:2px 0;color:var(--paper)}
.out ol strong{color:#fff}
.out .small{color:var(--muted)}
.verdict{font-weight:600;padding:12px 14px;margin:12px 0;border-radius:10px;background:var(--pine-tint);color:var(--pine)}
.verdict.fail{background:var(--brick-tint);color:var(--brick-dark)}
.formula{font-family:var(--mono);font-size:16px;background:var(--ink);color:var(--paper);border-radius:10px;padding:14px 16px;display:inline-block;max-width:100%;overflow-x:auto}

/* footer */
.site-foot{border-top:1px solid var(--grid);padding:40px 0 48px;font-size:14.5px;line-height:1.6;color:var(--body);background:var(--paper)}
.site-foot p{margin:8px 0;max-width:62em}
.foot-brand{display:flex;align-items:center;gap:10px;font-weight:700;font-size:18px;color:var(--ink)}
.site-foot .cred{margin:12px 0 8px;color:var(--ink);font-size:14.5px}
.site-foot ul{list-style:none;padding:0;margin:14px 0;display:flex;flex-wrap:wrap;gap:0 18px}
.site-foot ul a{display:inline-flex;align-items:center;min-height:44px}
.site-foot a{color:var(--pine)}

@media (max-width:599px){.readout{font-size:13px;padding:12px}.post ol,.out ol{font-size:14px;padding:12px 14px}}
@media (min-width:600px){
  .wrap{padding:0 24px}
  .cards,.samples,.tiles,.links,ol.toc{grid-template-columns:1fr 1fr}
  .rules4{grid-template-columns:1fr 1fr}
  .topics{grid-template-columns:1fr 1fr}
  .bundle-band{padding:28px 32px}
  .worked{padding:26px}
}
@media (min-width:900px){
  body{font-size:17.5px}
  .sec{padding-top:72px;padding-bottom:72px}
  .hero{padding:72px 0 80px}
  .hero.slim{padding:52px 0 44px}
  .hero-grid{grid-template-columns:1.15fr 1fr;gap:48px}
  .cards{grid-template-columns:repeat(4,1fr)}
  .rules4{grid-template-columns:repeat(4,1fr)}
  .tiles{grid-template-columns:repeat(3,1fr)}
  .tiles>li:first-child{grid-row:span 2}
  .sampler{grid-template-columns:1.05fr 1fr;gap:48px}
  .product-top{grid-template-columns:340px 1fr;gap:48px}
  .cover-big{max-width:340px}
  .two{grid-template-columns:1.15fr 1fr;gap:44px}
  .samples.s3{grid-template-columns:repeat(3,1fr)}
  .samples.s4{grid-template-columns:repeat(4,1fr)}
  .calc-wrap{grid-template-columns:1.05fr 1fr;gap:44px}
  .logo span{font-size:22px}
  .site-nav a{font-size:16px}
}
@media (prefers-reduced-motion:no-preference){html{scroll-behavior:smooth}}
@media print{.site-nav,.btns,.skip{display:none}body,.sq,.dark{background:#fff;color:#000}}