/* ML Tools — design tokens
   Navy ink + cool warehouse grey, shipping-label yellow for highlights.
   Receipts (monospace slips) are reserved for anything that is a calculation. */
:root{
  --ink:#03244e;
  --ink-2:#1d3f72;
  --muted:#525d6e;
  --bg:#edf0f4;
  --surface:#ffffff;
  --rule:#d4dae3;
  --rule-strong:#b9c2cf;
  --label:#f9c846;
  --label-soft:#fdf0c4;
  --profit:#16714a;
  --loss:#b3261e;
  --paper:#fffef8;
  --display:'Archivo',system-ui,-apple-system,sans-serif;
  --text:'Source Serif 4',Georgia,serif;
  --ui:'Archivo',system-ui,-apple-system,sans-serif;
  --mono:'IBM Plex Mono',ui-monospace,monospace;
  --r-sm:6px;
  --r-md:10px;
}
*,*::before,*::after{box-sizing:border-box;}
html{-webkit-text-size-adjust:100%;}
body{
  margin:0;background:var(--bg);color:var(--ink);
  font-family:var(--ui);font-size:16px;line-height:1.55;
  -webkit-font-smoothing:antialiased;
  font-variant-numeric:tabular-nums;
}
img{max-width:100%;display:block;}
a{color:var(--ink-2);text-decoration-thickness:1px;text-underline-offset:3px;}
a:hover{color:var(--ink);text-decoration-color:var(--label);text-decoration-thickness:3px;}
:focus-visible{outline:3px solid var(--label);outline-offset:2px;border-radius:3px;}
[hidden]{display:none!important;}
.skip{position:absolute;left:-999px;top:8px;background:var(--ink);color:#fff;padding:8px 12px;z-index:99;}
.skip:focus{left:8px;}

.wrap{max-width:1160px;margin:0 auto;padding:0 24px;}
@media (max-width:600px){.wrap{padding:0 16px;}}

h1,h2,h3,h4{font-family:var(--display);color:var(--ink);margin:0;}
h1{font-size:clamp(2rem,4.6vw,3.4rem);line-height:1.04;font-weight:800;font-stretch:112%;letter-spacing:-0.025em;}
h2{font-size:1.55rem;line-height:1.2;font-weight:750;font-stretch:108%;letter-spacing:-0.012em;}
h3{font-size:1.15rem;line-height:1.3;font-weight:700;}

/* ---------- nav ---------- */
.site-nav{background:var(--ink);color:#fff;}
.site-nav .wrap{display:flex;align-items:center;justify-content:space-between;gap:20px;min-height:64px;flex-wrap:wrap;}
.wordmark{display:flex;align-items:center;gap:10px;color:#fff;text-decoration:none;font-family:var(--display);font-weight:800;font-stretch:118%;font-size:1.15rem;letter-spacing:-0.01em;}
.wordmark:hover{color:#fff;text-decoration:none;}
.wordmark img{height:40px;width:auto;}
.wordmark .tools{font-family:var(--display);font-weight:700;font-stretch:112%;font-size:1rem;color:var(--ink);background:var(--label);padding:3px 9px;border-radius:5px;letter-spacing:0;}
.site-footer .wordmark img{height:46px;}
.nav-links{display:flex;gap:4px;list-style:none;margin:0;padding:0;}
.nav-links a{display:block;color:#dfe5ef;text-decoration:none;font-size:.95rem;font-weight:500;padding:8px 12px;border-radius:var(--r-sm);}
.nav-links a:hover{background:var(--ink-2);color:#fff;}
.nav-links a[aria-current="page"]{color:var(--ink);background:var(--label);}
@media (max-width:600px){.wordmark img{height:32px;}.wordmark .tools{font-size:.85rem;padding:2px 7px;}.nav-links a{padding:8px 9px;font-size:.9rem;}}

/* ---------- home hero ---------- */
.hero{background:var(--ink);color:#fff;padding:56px 0 0;overflow:hidden;}
.hero-grid{display:grid;grid-template-columns:1.1fr .9fr;gap:56px;align-items:end;}
.hero h1{color:#fff;max-width:13ch;}
.hero .lede{font-family:var(--text);font-size:1.2rem;line-height:1.55;color:#cfd7e4;max-width:34em;margin:22px 0 28px;}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;padding-bottom:56px;}
.btn{display:inline-flex;align-items:center;gap:8px;font-family:var(--ui);font-weight:650;font-size:1rem;padding:12px 18px;border-radius:var(--r-sm);text-decoration:none;border:2px solid transparent;cursor:pointer;}
.btn-primary{background:var(--label);color:var(--ink);}
.btn-primary:hover{background:#ffd866;color:var(--ink);text-decoration:none;}
.btn-ghost{border-color:#5b6f94;color:#fff;}
.btn-ghost:hover{border-color:#fff;color:#fff;text-decoration:none;}
@media (max-width:860px){.hero-grid{grid-template-columns:1fr;gap:8px;}.hero-actions{padding-bottom:36px;}}

/* the slip: a printed payout receipt */
.slip{
  position:relative;background:var(--paper);color:var(--ink);
  font-family:var(--mono);font-size:.92rem;
  padding:22px 24px 30px;
  box-shadow:0 1px 0 rgba(3,36,78,.08),0 12px 30px -12px rgba(3,36,78,.35);
  --tear:10px;
  -webkit-mask:linear-gradient(#000 0 0) top/100% calc(100% - var(--tear)) no-repeat,
    conic-gradient(from -45deg at bottom,#0000,#000 1deg 89deg,#0000 90deg) bottom/calc(var(--tear)*2) var(--tear) repeat-x;
          mask:linear-gradient(#000 0 0) top/100% calc(100% - var(--tear)) no-repeat,
    conic-gradient(from -45deg at bottom,#0000,#000 1deg 89deg,#0000 90deg) bottom/calc(var(--tear)*2) var(--tear) repeat-x;
}
.slip-head{display:flex;justify-content:space-between;gap:12px;font-size:.8rem;color:var(--muted);padding-bottom:12px;border-bottom:1px dashed var(--rule-strong);margin-bottom:8px;}
.slip-row{display:flex;justify-content:space-between;gap:16px;padding:5px 0;}
.slip-row .k{color:var(--muted);}
.slip-row .v{font-weight:600;white-space:nowrap;}
.slip-row.minus .v{color:var(--loss);}
.slip-total{display:flex;justify-content:space-between;gap:16px;border-top:1px dashed var(--rule-strong);margin-top:10px;padding-top:12px;font-size:1.1rem;font-weight:600;}
.slip-total .v{background:var(--label-soft);padding:0 6px;border-radius:3px;}
.slip-total .v.neg{background:#fbe1de;color:var(--loss);}
.slip-total .v.pos{color:var(--profit);}
.slip-note{font-size:.78rem;color:var(--muted);margin:14px 0 0;line-height:1.45;}

.hero .slip{transform:translateY(0);margin-bottom:-1px;}
.slip-controls{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:4px 0 12px;}
.slip-controls label{display:flex;flex-direction:column;gap:3px;font-size:.75rem;color:var(--muted);}
.slip-controls input,.slip-controls select{font:600 .95rem var(--mono);color:var(--ink);background:#fff;border:1px solid var(--rule-strong);border-radius:4px;padding:7px 8px;width:100%;}
.slip-controls .full{grid-column:1/-1;}
.seg{display:flex;border:1px solid var(--rule-strong);border-radius:5px;overflow:hidden;}
.seg button{flex:1;font:600 .82rem var(--ui);background:#fff;color:var(--muted);border:0;padding:8px 4px;cursor:pointer;border-right:1px solid var(--rule);}
.seg button:last-child{border-right:0;}
.seg button[aria-pressed="true"]{background:var(--ink);color:#fff;}

/* ---------- sections ---------- */
.section{padding:72px 0;}
.section + .section{padding-top:0;}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:20px;margin-bottom:26px;flex-wrap:wrap;}
.section-head p{color:var(--muted);margin:6px 0 0;max-width:46em;}
.section-head .more{font-weight:600;}

/* tool index: list rows, not cards */
.tool-index{list-style:none;margin:0;padding:0;background:var(--surface);border-radius:var(--r-md);border:1px solid var(--rule);}
.tool-index li + li{border-top:1px solid var(--rule);}
.tool-index a{display:grid;grid-template-columns:minmax(220px,1fr) 1.4fr auto;gap:24px;align-items:center;padding:20px 24px;text-decoration:none;color:var(--ink);}
.tool-index a:hover{background:#f6f8fb;}
.tool-index a:hover .go{background:var(--label);border-color:var(--label);}
.tool-index .name{font-family:var(--display);font-weight:700;font-size:1.08rem;}
.tool-index .q{color:var(--muted);font-family:var(--text);font-size:1.02rem;}
.tool-index .go{font-weight:600;font-size:.9rem;border:1.5px solid var(--rule-strong);padding:7px 12px;border-radius:var(--r-sm);white-space:nowrap;}
@media (max-width:760px){.tool-index a{grid-template-columns:1fr;gap:6px;padding:18px;}.tool-index .go{justify-self:start;margin-top:6px;}}

/* guide shelves */
.shelves{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:40px 32px;}
.shelf h3{font-size:1rem;padding-bottom:10px;border-bottom:3px solid var(--ink);margin-bottom:6px;}
.shelf ul{list-style:none;margin:0;padding:0;}
.shelf li{border-bottom:1px solid var(--rule);}
.shelf a{display:block;padding:12px 0;text-decoration:none;color:var(--ink);font-family:var(--text);font-size:1.05rem;line-height:1.35;}
.shelf a:hover{color:var(--ink-2);text-decoration:underline;text-decoration-color:var(--label);text-decoration-thickness:3px;}
.shelf .rt{display:block;font-family:var(--ui);font-size:.8rem;color:var(--muted);margin-top:3px;}

.author-strip{background:var(--surface);border:1px solid var(--rule);border-radius:var(--r-md);padding:32px;display:grid;grid-template-columns:auto 1fr;gap:28px;align-items:start;}
.author-strip .avatar{width:72px;height:72px;border-radius:50%;background:var(--ink);color:var(--label);display:grid;place-items:center;font:800 1.5rem var(--display);font-stretch:115%;}
.author-strip p{font-family:var(--text);font-size:1.08rem;color:#2c3a52;margin:10px 0 0;max-width:46em;}
@media (max-width:600px){.author-strip{grid-template-columns:1fr;padding:22px;}}

/* ---------- page heads ---------- */
.page-head{background:var(--surface);border-bottom:1px solid var(--rule);padding:44px 0 36px;}
.crumbs{font-size:.88rem;color:var(--muted);margin-bottom:14px;}
.crumbs a{color:var(--muted);}
.page-head h1{font-size:clamp(1.9rem,3.8vw,2.8rem);max-width:22ch;}
.page-head .dek{font-family:var(--text);font-size:1.2rem;color:#384660;max-width:38em;margin:14px 0 0;line-height:1.5;}
.byline{display:flex;flex-wrap:wrap;gap:6px 18px;margin-top:20px;font-size:.9rem;color:var(--muted);}
.byline strong{color:var(--ink);font-weight:600;}

/* ---------- calculator pages ---------- */
.calc-layout{display:grid;grid-template-columns:minmax(0,1fr) 380px;gap:32px;align-items:start;padding:36px 0 8px;}
@media (max-width:920px){.calc-layout{grid-template-columns:1fr;}}
.panel{background:var(--surface);border:1px solid var(--rule);border-radius:var(--r-md);padding:26px;}
.panel h2{font-size:1.1rem;margin-bottom:16px;}
.field-grid{display:grid;grid-template-columns:1fr 1fr;gap:18px;}
.field{display:flex;flex-direction:column;gap:6px;}
.field.full{grid-column:1/-1;}
.field label{font-size:.9rem;font-weight:600;color:var(--ink);}
.field .hint{font-size:.8rem;color:var(--muted);}
.field input,.field select{font:500 1.02rem var(--ui);font-variant-numeric:tabular-nums;color:var(--ink);background:#fff;border:1.5px solid var(--rule-strong);border-radius:var(--r-sm);padding:11px 12px;width:100%;min-height:46px;}
.field input:focus,.field select:focus{border-color:var(--ink);outline:3px solid var(--label-soft);outline-offset:0;}
.check{display:flex;gap:10px;align-items:flex-start;font-size:.92rem;}
.check input{width:18px;height:18px;margin-top:2px;accent-color:var(--ink);}
@media (max-width:560px){.field-grid{grid-template-columns:1fr;}.panel{padding:20px;}}
.result-col{position:sticky;top:16px;}
@media (max-width:920px){.result-col{position:static;}}
.verdict{margin-top:14px;background:var(--ink);color:#fff;border-radius:var(--r-sm);padding:14px 16px;font-size:.98rem;}
.verdict b{color:var(--label);}

.compare{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:18px;}
@media (max-width:820px){.compare{grid-template-columns:1fr;}}
.compare .slip{font-size:.86rem;padding:18px 18px 26px;}
.compare .slip.win .slip-head{color:var(--profit);font-weight:600;}

/* ---------- prose (guides + calculator write-ups) ---------- */
.article-layout{display:grid;grid-template-columns:minmax(0,680px) 280px;gap:64px;justify-content:space-between;padding-top:44px;padding-bottom:24px;}
@media (max-width:980px){.article-layout{grid-template-columns:minmax(0,1fr);gap:0;}}
.prose{font-family:var(--text);font-size:1.13rem;line-height:1.72;color:#22314b;}
.prose > *{max-width:680px;}
.prose p{margin:0 0 1.1em;}
.prose h2{font-size:1.6rem;margin:2.1em 0 .6em;scroll-margin-top:20px;}
.prose h3{font-size:1.2rem;margin:1.7em 0 .45em;}
.prose h2:first-child{margin-top:0;}
.prose ul,.prose ol{padding-left:1.3em;margin:0 0 1.2em;}
.prose li{margin-bottom:.45em;}
.prose li::marker{color:var(--ink-2);}
.prose strong{color:var(--ink);font-weight:650;}
.prose code{font-family:var(--mono);font-size:.88em;background:#e8ecf2;padding:1px 5px;border-radius:3px;}
.prose .formula{font-family:var(--mono);font-size:.98rem;background:var(--surface);border-left:4px solid var(--label);padding:14px 18px;margin:0 0 1.3em;border-radius:0 var(--r-sm) var(--r-sm) 0;color:var(--ink);overflow-x:auto;}
.prose .slip{font-size:.92rem;line-height:1.5;margin:1.6em 0 1.8em;max-width:460px;}
.prose .slip p{margin:0;}
.note{background:var(--surface);border:1px solid var(--rule);border-left:4px solid var(--ink);border-radius:var(--r-sm);padding:18px 20px;margin:1.6em 0;font-size:1.02rem;}
.note .who{display:block;font-family:var(--ui);font-weight:700;font-size:.85rem;color:var(--ink);margin-bottom:6px;}
.note p:last-child{margin-bottom:0;}
.warn{border-left-color:var(--loss);}
.tool-cta{display:flex;justify-content:space-between;align-items:center;gap:16px;flex-wrap:wrap;background:var(--label-soft);border:1px solid #efd88a;border-radius:var(--r-md);padding:18px 20px;margin:2em 0;font-family:var(--ui);font-size:1rem;}
.tool-cta strong{display:block;font-size:1.05rem;}
.tool-cta span{color:#4a4a3a;}
.tool-cta .btn{background:var(--ink);color:#fff;}
.tool-cta .btn:hover{background:var(--ink-2);color:#fff;}

.table-scroll{overflow-x:auto;margin:1.2em 0 1.6em;border:1px solid var(--rule);border-radius:var(--r-sm);background:var(--surface);}
.data-table{width:100%;border-collapse:collapse;font-family:var(--ui);font-size:.95rem;line-height:1.4;}
.data-table caption{caption-side:top;text-align:left;font-size:.85rem;color:var(--muted);padding:12px 14px 4px;}
.data-table th,.data-table td{text-align:left;padding:10px 14px;border-bottom:1px solid var(--rule);vertical-align:top;}
.data-table thead th{font-weight:700;font-size:.85rem;color:var(--ink);background:#f4f6f9;}
.data-table tr:last-child td{border-bottom:0;}
.data-table .num{text-align:right;white-space:nowrap;}

.faq{margin-top:.5em;}
.faq details{border-top:1px solid var(--rule);padding:4px 0;}
.faq details:last-child{border-bottom:1px solid var(--rule);}
.faq summary{cursor:pointer;font-family:var(--display);font-weight:700;font-size:1.08rem;color:var(--ink);padding:14px 28px 14px 0;list-style:none;position:relative;}
.faq summary::-webkit-details-marker{display:none;}
.faq summary::after{content:"+";position:absolute;right:4px;top:10px;font-size:1.4rem;font-weight:400;color:var(--muted);}
.faq details[open] summary::after{content:"\2212";}
.faq details p{margin:0 0 16px;}

.sources{font-family:var(--ui);font-size:.92rem;color:var(--muted);border-top:1px solid var(--rule);margin-top:2.4em;padding-top:18px;}
.sources h2{font-size:1rem;margin:0 0 8px;}
.sources ul{padding-left:1.1em;margin:0;}
.sources li{margin-bottom:4px;}
.updated{font-family:var(--ui);font-size:.88rem;color:var(--muted);}

/* sidebar */
.aside{position:sticky;top:20px;align-self:start;font-size:.92rem;}
@media (max-width:980px){.aside{position:static;margin-top:8px;}}
.aside .box{background:var(--surface);border:1px solid var(--rule);border-radius:var(--r-md);padding:18px 20px;margin-bottom:18px;}
.aside h2{font-size:.95rem;margin:0 0 10px;}
.toc{list-style:none;margin:0;padding:0;}
.toc li{margin:0;}
.toc a{display:block;padding:6px 0 6px 12px;border-left:2px solid var(--rule);color:var(--muted);text-decoration:none;line-height:1.35;}
.toc a:hover{color:var(--ink);border-left-color:var(--label);}
.aside .tool-link{display:block;font-family:var(--display);font-weight:700;font-size:1.02rem;color:var(--ink);text-decoration:none;margin-bottom:4px;}
.aside .tool-link:hover{text-decoration:underline;text-decoration-color:var(--label);text-decoration-thickness:3px;}
.aside p{margin:0 0 10px;color:var(--muted);}
@media (max-width:980px){.aside .toc-box{display:none;}}

.related{padding:16px 0 64px;}
.related h2{font-size:1.25rem;margin-bottom:14px;}
.related ul{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:12px;}
.related a{display:block;height:100%;background:var(--surface);border:1px solid var(--rule);border-radius:var(--r-sm);padding:16px 18px;text-decoration:none;color:var(--ink);font-family:var(--text);font-size:1.03rem;line-height:1.35;}
.related a:hover{border-color:var(--ink);}
.related small{display:block;font-family:var(--ui);color:var(--muted);font-size:.8rem;margin-bottom:4px;}

/* guides hub */
.hub-group{margin-bottom:48px;}
.hub-group > h2{font-size:1.3rem;padding-bottom:10px;border-bottom:3px solid var(--ink);margin-bottom:4px;}
.hub-group > p{color:var(--muted);margin:10px 0 8px;max-width:46em;}
.hub-list{list-style:none;margin:0;padding:0;}
.hub-list li{border-bottom:1px solid var(--rule);}
.hub-list a{display:grid;grid-template-columns:1fr auto;gap:4px 24px;padding:18px 0;text-decoration:none;color:var(--ink);}
.hub-list .t{font-family:var(--display);font-weight:700;font-size:1.12rem;}
.hub-list .d{font-family:var(--text);color:var(--muted);grid-column:1;font-size:1.02rem;}
.hub-list .rt{grid-row:1/3;grid-column:2;align-self:center;font-size:.85rem;color:var(--muted);white-space:nowrap;}
.hub-list a:hover .t{text-decoration:underline;text-decoration-color:var(--label);text-decoration-thickness:3px;}
@media (max-width:600px){.hub-list a{grid-template-columns:1fr;}.hub-list .rt{grid-row:auto;grid-column:1;}}

/* simple pages */
.simple{padding-top:40px;padding-bottom:64px;}
.simple .prose{max-width:720px;}

/* footer */
.site-footer{background:var(--ink);color:#b8c3d6;margin-top:24px;padding:48px 0 32px;font-size:.92rem;}
.foot-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:32px;}
.site-footer h2{color:#fff;font-size:.95rem;margin:0 0 12px;}
.site-footer ul{list-style:none;margin:0;padding:0;}
.site-footer li{margin-bottom:8px;}
.site-footer a{color:#dfe5ef;text-decoration:none;}
.site-footer a:hover{color:#fff;text-decoration:underline;text-decoration-color:var(--label);}
.site-footer p{margin:10px 0 0;max-width:30em;}
.foot-base{border-top:1px solid #2c4268;margin-top:36px;padding-top:20px;display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;font-size:.85rem;}
@media (max-width:820px){.foot-grid{grid-template-columns:1fr 1fr;}}
@media (max-width:480px){.foot-grid{grid-template-columns:1fr;}}

@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important;scroll-behavior:auto!important;}}
@media print{.site-nav,.site-footer,.aside,.tool-cta{display:none;}body{background:#fff;}}