:root{
  --bg:#f6f7f9;--surface:#fff;--ink:#14213d;--muted:#5b6475;--line:#dde2ea;
  --brand:#0b5fff;--brand-ink:#fff;--band:#0f2a5c;--band-ink:#eef3ff;--accent:#ffb703;
  --ok-bg:#eaf2ff;--radius:14px;--shadow:0 6px 24px rgba(15,42,92,.10);
  --font:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.65 var(--font)}
a{color:var(--brand)}
img,svg{max-width:100%;height:auto}
.wrap{max-width:1120px;margin:0 auto;padding:0 16px}
.skip{position:absolute;left:-999px}.skip:focus{left:16px;top:8px;background:#fff;padding:8px;z-index:9}

header.top{background:var(--band);color:var(--band-ink)}
header.top .wrap{display:flex;align-items:center;justify-content:space-between;height:56px}
.logo{color:#fff;text-decoration:none;font-weight:700;display:flex;gap:8px;align-items:center}
header.top nav a{color:var(--band-ink);text-decoration:none;margin-left:18px;font-size:15px}
header.top nav a:hover{text-decoration:underline}

.hero{background:var(--band);color:var(--band-ink);padding:28px 0 56px}
.hero .wrap{display:grid;grid-template-columns:1fr 1.05fr;gap:40px;align-items:start}
.hero h1{color:#fff;font-size:clamp(28px,4vw,42px);line-height:1.15;margin:8px 0 14px}
.hero p.lead{font-size:18px;margin:0 0 18px;color:#d7e2ff}
.hero ul{margin:0;padding-left:20px;color:#d7e2ff}
.hero ul li{margin:4px 0}
.diagram{margin-top:22px;max-width:260px}

.calc{background:var(--surface);color:var(--ink);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px}
.calc h2{font-size:20px;margin:0 0 14px}
.field{margin-bottom:14px}
.field label{display:block;font-weight:600;font-size:15px;margin-bottom:6px}
.row{display:grid;grid-template-columns:1fr 110px;gap:8px}
.row3{display:grid;grid-template-columns:1fr 1fr;gap:12px}
input,select{width:100%;font:inherit;font-size:17px;padding:11px 12px;border:1px solid var(--line);border-radius:10px;background:#fff;color:var(--ink)}
input:focus,select:focus{outline:3px solid rgba(11,95,255,.25);border-color:var(--brand)}
.hint{font-size:13px;color:var(--muted);margin-top:4px}
.btn{display:inline-block;background:var(--brand);color:var(--brand-ink);border:0;border-radius:10px;padding:12px 18px;font:inherit;font-weight:700;cursor:pointer;transition:transform .15s,box-shadow .15s}
.btn:hover{transform:translateY(-1px);box-shadow:0 6px 16px rgba(11,95,255,.3)}
.btn.ghost{background:transparent;color:var(--brand);border:1px solid var(--line)}
.actions{display:flex;gap:10px;flex-wrap:wrap}
.result{margin-top:16px;background:var(--ok-bg);border-radius:12px;padding:16px;min-height:72px}
.result .big{font-size:28px;font-weight:800;line-height:1.2;word-break:break-word}
.result .units{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 14px;margin-top:10px;font-size:15px}
.result .units b{font-variant-numeric:tabular-nums}
.steps{margin-top:10px;font-size:14px;color:var(--muted)}
.steps code{background:#fff;padding:1px 5px;border-radius:5px;color:var(--ink)}
.err{color:#b00020;font-weight:600}
[hidden]{display:none!important}

main section{padding:48px 0;border-bottom:1px solid var(--line)}
main section:last-child{border-bottom:0}
main h2{font-size:clamp(24px,3vw,30px);line-height:1.25;margin:0 0 14px}
main h3{font-size:20px;margin:24px 0 8px}
.split{display:grid;grid-template-columns:1fr 1fr;gap:36px;align-items:start}
.split .sticky{position:sticky;top:16px}
.formula{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:20px;text-align:center}
.formula .f{font-size:clamp(26px,4vw,36px);font-weight:800;font-family:Georgia,"Times New Roman",serif;margin:6px 0}
.formula p{margin:6px 0;color:var(--muted)}
.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:18px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px;transition:transform .15s,box-shadow .15s}
.card:hover{transform:translateY(-2px);box-shadow:var(--shadow)}
.card .ico{width:40px;height:40px;border-radius:10px;background:var(--ok-bg);display:grid;place-items:center;margin-bottom:10px}
.card h3{margin:0 0 6px;font-size:18px}
.card p{margin:0;font-size:16px}
.example{background:var(--surface);border:1px solid var(--line);border-left:4px solid var(--accent);border-radius:10px;padding:16px 18px;margin:14px 0}
.example p{margin:4px 0}
.tbl{overflow-x:auto;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius)}
table{border-collapse:collapse;width:100%;font-size:15px;font-variant-numeric:tabular-nums}
th,td{padding:10px 12px;text-align:right;border-bottom:1px solid var(--line);white-space:nowrap}
th:first-child,td:first-child{text-align:left}
thead th{background:#eef2f8}
tbody tr:last-child td{border-bottom:0}
caption{caption-side:bottom;text-align:left;padding:10px 12px;color:var(--muted);font-size:14px}
details{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:14px 18px;margin:10px 0}
summary{font-weight:700;cursor:pointer}
details p{margin:10px 0 0}

footer{background:var(--band);color:var(--band-ink);padding:28px 0;font-size:15px}
footer a{color:#fff}

@media (max-width:900px){
  .hero .wrap,.split{grid-template-columns:1fr;gap:24px}
  .split .sticky{position:static}
  .cards{grid-template-columns:1fr}
  .diagram,.hero ul{display:none}
  .hero{padding:20px 0 40px}
  .hero p.lead{margin-bottom:0}
  header.top nav{display:none}
}
@media (max-width:420px){
  .row{grid-template-columns:1fr 92px}
  .row3{grid-template-columns:1fr}
  .result .units{grid-template-columns:1fr}
}

/* v2: calculator extras */
.seg{display:inline-flex;border:1px solid var(--line);border-radius:10px;overflow:hidden;margin-bottom:14px}
.seg button{font:inherit;font-size:15px;font-weight:600;padding:8px 16px;border:0;background:#fff;color:var(--muted);cursor:pointer}
.seg button[aria-pressed="true"]{background:var(--brand);color:#fff}
#more{margin-top:14px;border:1px solid var(--line);border-radius:10px;padding:10px 14px}
#more summary{font-weight:600;font-size:15px;cursor:pointer;color:var(--brand)}
#more[open] summary{margin-bottom:12px}
.actions{margin-top:14px}
.next{margin:10px 0 0;font-weight:600}

.detail{background:var(--bg);padding:32px 0 8px}
.dgrid{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.panel{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px;margin-bottom:20px}
.panel h2{font-size:20px;margin:0 0 10px}
.fig svg{width:100%;height:auto;display:block}
.fig .shell{fill:#e8efff;stroke:#0f2a5c;stroke-width:2}
.fig .liquid{fill:rgba(11,95,255,.45);stroke:none}
.fig .surface{fill:rgba(11,95,255,.6);stroke:#0b5fff;stroke-width:1}
.fig .top{fill:#cfdcff;stroke:#0f2a5c;stroke-width:2}
.fig .hole{fill:#fff;stroke:#0f2a5c;stroke-width:1.5}
.fig .rad{stroke:#e85d04;stroke-width:2}
.fig .dot{fill:#e85d04}
.fig .dim{stroke:#5b6475;stroke-width:1.5}
.fig .dash{fill:none;stroke:#5b6475;stroke-width:1.2;stroke-dasharray:5 4}
.fig .lbl{font:600 13px var(--font);fill:var(--ink)}
.fig .cap{font:12px var(--font);fill:var(--muted)}
.fig .axis{stroke:#14213d;stroke-width:1.2}
.fig .grid{stroke:#e3e8f0;stroke-width:1}
.fig .tick{font:11px var(--font);fill:var(--muted)}
.fig .line{fill:none;stroke:#0b5fff;stroke-width:2.5}
.fig .mark{fill:#e85d04;stroke:#fff;stroke-width:2}
.fillrow{margin-top:8px}
.fillrow label{font-weight:600;font-size:15px}
.fillrow input[type=range]{width:100%;padding:0;border:0;accent-color:var(--brand)}
.lpc{background:var(--ok-bg);border-radius:10px;padding:10px 12px;margin:10px 0 0;font-size:15px}
.whead{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap}
.work h3{font-size:16px;margin:14px 0 6px;color:var(--muted);text-transform:uppercase;letter-spacing:.04em}
.work ul,.work ol{margin:0;padding-left:22px}
.work li{margin:3px 0;font-variant-numeric:tabular-nums}
.work code{background:var(--ok-bg);padding:2px 6px;border-radius:6px;font-size:15px}
#tara summary{font-weight:700;cursor:pointer}
.tara-tools{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:10px 0}
.tara-tools select{width:auto}
.tara-tools label{font-weight:600}
#tara .tbl{max-height:420px;overflow:auto}
.chips{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:8px}
.chip{font:inherit;font-size:15px;text-align:left;width:100%;background:var(--ok-bg);border:1px solid var(--line);border-radius:10px;padding:8px 12px;cursor:pointer;color:var(--ink)}
.chip:hover{border-color:var(--brand)}
.practice{max-width:640px}
.exq{font-size:18px;font-weight:600}
.ex-row{grid-template-columns:1fr auto;align-items:center}
.exu{font-weight:600;color:var(--muted)}
#exF.ok{color:#0a7d32;font-weight:700}
#exF.err{color:#b00020;font-weight:700}

@media (max-width:900px){.dgrid{grid-template-columns:1fr;gap:0}}


.split>*,.dgrid>*,.hero .wrap>*{min-width:0}
.work code,.steps code{font-family:var(--font)}

/* v3: site-wide parts */
header.top .wrap{gap:16px}
.mainnav{display:flex;gap:4px;overflow-x:auto;scrollbar-width:none}
.mainnav::-webkit-scrollbar{display:none}
header.top .mainnav a{margin:0;padding:6px 10px;border-radius:8px;white-space:nowrap}
header.top .mainnav a[aria-current="page"]{background:rgba(255,255,255,.14);color:#fff}
.crumbs{font-size:14px;color:#c3d0ee;margin-bottom:6px}
.crumbs a{color:#fff}
.answer{background:rgba(255,255,255,.08);border-left:4px solid var(--accent);border-radius:8px;padding:12px 14px;color:#eef3ff;margin:0 0 16px;font-size:17px}
.answer b{color:#fff}
.hero-plain{padding-bottom:32px}
.hero-plain .wrap{display:block}
.narrow{max-width:760px}
.card.link{display:block;text-decoration:none;color:var(--ink)}
.card.link h3{color:var(--brand)}
.cards-1{grid-template-columns:1fr}
.footnav{display:flex;flex-wrap:wrap;gap:6px 18px;margin-bottom:12px}
.footnav a{color:#fff;text-decoration:none}
.footnav a:hover{text-decoration:underline}
footer p a{color:#fff}
table.wrap-cells td,table.wrap-cells th{white-space:normal}
.contact textarea{width:100%;font:inherit;font-size:17px;padding:11px 12px;border:1px solid var(--line);border-radius:10px;resize:vertical}
.hp{position:absolute;left:-5000px;width:1px;height:1px;overflow:hidden}
.notice{border-radius:10px;padding:12px 14px;font-weight:600}
.notice.ok{background:#e7f6ec;color:#0a5c27}
.notice.err{background:#fdecee;color:#8a0016}
.cf-turnstile{margin:6px 0 10px}
.links404{display:flex;flex-wrap:wrap;gap:8px}
.legal h3{font-size:18px;margin:18px 0 6px}
ol.steps{padding-left:20px;margin:8px 0 0}
@media (max-width:900px){
  header.top .wrap{height:auto;flex-direction:column;align-items:flex-start;padding-top:10px;padding-bottom:8px;gap:6px}
  header.top nav.mainnav{display:flex;width:100%}
}


/* audit fixes 12 Oct */
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.histbox{margin-top:16px;border-top:1px solid var(--line);padding-top:12px}
.histbox h3{font-size:16px;margin:0 0 8px}
.calc.solver{max-width:640px;margin-top:16px}
.tbl:focus{outline:3px solid rgba(11,95,255,.35);outline-offset:2px}
.hero404 .btn.ghost{color:#fff;border-color:rgba(255,255,255,.7)}
@media (max-width:900px){
  /* calculator first on phones: crumbs, H1, calculator, then the short answer */
  .hero .wrap>div:first-child{display:contents}
  .hero .crumbs{order:0}
  .hero h1{order:1;margin-bottom:4px}
  .hero .calc{order:2}
  .hero .answer{order:3;margin-top:4px}
  .hero .lead{order:4}
  .hero .wrap{gap:14px}
  header.top .mainnav a{min-height:44px;display:inline-flex;align-items:center}
  .logo{min-height:44px}
}
@media print{
  body.print-tab .skip, body.print-tab header.top, body.print-tab footer, body.print-tab .hero, body.print-tab main,
  body.print-tab #faq, body.print-tab #detail .dgrid, body.print-tab #detail .work, body.print-tab .tara-tools{display:none}
  body.print-tab #detail{padding:0}
  body.print-tab #tara{border:0;margin:0}
  body.print-tab #tara .tbl{max-height:none;overflow:visible;border:0}
  body.print-sheet .skip, body.print-sheet header.top, body.print-sheet footer, body.print-sheet .hero,
  body.print-sheet main>section:not(#formulario), body.print-sheet #faq, body.print-sheet #fPrint{display:none}
  body.print-sheet #formulario{padding:0;border:0}
}