:root{
  --bg:#0A0A0A; --surface:#131313; --surface-2:#1C1C1C; --surface-3:#262626; --line:#2A2A2A;
  --fg:#F0F0F0; --muted:#A6A6A6; --dim:#777777;
  --accent:#00B000; --accent-bright:#88EF1B; --loss:#FF5A4E; --warn:#E9B43C;
  --f-display:"Geologica","Figtree",system-ui,sans-serif; --f-body:"Figtree",system-ui,-apple-system,"Segoe UI",sans-serif; --f-mono:"IBM Plex Mono",ui-monospace,Menlo,monospace;
  --wrap:1160px; --gut:clamp(16px,4vw,32px);
  color-scheme:dark;
}
/* La web de Fibonacci es solo oscura (marca): los mismos tokens valen en ambos temas. */
@media (prefers-color-scheme:light){:root:not([data-theme="light"]){--bg:#0A0A0A}}
:root[data-theme="dark"]{--bg:#0A0A0A}
*{box-sizing:border-box;margin:0}
[hidden]{display:none!important}
body{background:var(--bg);color:var(--fg);font:16px/1.55 var(--f-body);-webkit-font-smoothing:antialiased;overflow-x:hidden}
a{color:inherit}
:focus-visible{outline:2px solid var(--accent-bright);outline-offset:3px;border-radius:6px}
.wrap{max-width:var(--wrap);margin:0 auto;padding-inline:var(--gut)}
h1,h2,h3{font-family:var(--f-display);letter-spacing:-.03em;line-height:1.05;text-wrap:balance}
h1{font-weight:800;font-size:clamp(40px,6.4vw,80px);letter-spacing:-.045em;line-height:.92;text-transform:uppercase;max-width:16ch}
h1 em{font-style:normal;color:var(--accent)}
h2{font-weight:800;font-size:clamp(30px,3.6vw,46px);letter-spacing:-.04em;line-height:.95}
h3{font-size:18px;font-weight:700}
.kicker{display:inline-flex;align-items:center;gap:10px;font:500 13px/1 var(--f-mono);letter-spacing:.14em;text-transform:uppercase;color:var(--accent)}
.kicker::before{content:"";width:8px;height:8px;border-radius:99px;background:var(--accent);box-shadow:0 0 0 4px rgba(0,176,0,.24)}
.lead{font-size:clamp(17px,1.6vw,20px);color:var(--muted);max-width:56ch}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:10px;padding:14px 24px;border-radius:99px;font-weight:600;font-size:15px;text-decoration:none;white-space:nowrap}
.btn.primary{background:#88EF1B;color:#131313}.btn.primary:hover{background:#9DF53F}

/* Cabecera igual que la home */
header{background:rgba(10,10,10,.82);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;gap:28px;height:68px}
.nav .logo img{height:34px;width:auto;display:block}
.nav ul{display:flex;gap:24px;list-style:none;padding:0;margin-left:auto;font-size:14px}
.nav ul a{color:var(--muted);text-decoration:none}.nav ul a:hover{color:var(--fg)}
.nav .btn{padding:10px 18px;font-size:14px}
@media (max-width:860px){.nav ul{display:none}.nav .btn{margin-left:auto}}

/* Hero de la calculadora */
.calc-hero{position:relative;overflow:hidden;padding-block:clamp(40px,6vw,80px) 32px;isolation:isolate}
.calc-hero::before{content:"";position:absolute;inset:-30% -10% auto -10%;height:130%;z-index:-1;background:radial-gradient(55% 55% at 15% 20%,rgba(0,176,0,.30),transparent 70%),radial-gradient(40% 45% at 90% 60%,rgba(0,132,0,.32),transparent 70%);filter:blur(30px)}
.calc-hero .wrap{display:flex;flex-direction:column;gap:20px}
.crumbs{font-size:13px;color:var(--dim)}.crumbs a{color:var(--muted);text-decoration:none}

/* Tarjeta de cálculo */
.tool{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(0,.85fr);border:1px solid var(--line);border-radius:22px;background:var(--surface);overflow:hidden;margin-bottom:clamp(56px,8vw,96px)}
.fields{padding:clamp(20px,3vw,36px);display:grid;grid-template-columns:1fr 1fr;gap:18px 16px;align-content:start}
.field{display:flex;flex-direction:column;gap:8px;min-width:0}
.field.full{grid-column:1/-1}
.field label,.field .lbl{font-size:14px;font-weight:600}
.field small{font-size:12.5px;color:var(--dim);line-height:1.4}
.input{display:flex;align-items:center;border:1px solid var(--line);background:var(--surface-2);border-radius:12px;transition:border-color .15s}
.input:focus-within{border-color:var(--accent)}
.input input,.input select,.input textarea{flex:1;min-width:0;background:transparent;border:0;color:var(--fg);font:500 17px var(--f-mono);padding:13px 14px;outline:none;appearance:none}
.input select{font-family:var(--f-body);font-size:16px;cursor:pointer;background-image:linear-gradient(45deg,transparent 50%,var(--muted) 50%),linear-gradient(135deg,var(--muted) 50%,transparent 50%);background-position:calc(100% - 18px) 55%,calc(100% - 13px) 55%;background-size:5px 5px;background-repeat:no-repeat;padding-right:34px}
.input select option{background:var(--surface-2)}
.input .unit{padding-right:14px;color:var(--dim);font:500 13px var(--f-mono);white-space:nowrap}
.input .pre{padding:0 0 0 14px;color:var(--dim);font:500 13px var(--f-mono);white-space:nowrap}
.seg{display:grid;grid-auto-flow:column;grid-auto-columns:1fr;border:1px solid var(--line);border-radius:12px;padding:4px;background:var(--surface-2)}
.seg input{position:absolute;opacity:0;pointer-events:none}
.seg label{text-align:center;padding:9px 8px;border-radius:9px;font-size:14px;color:var(--muted);cursor:pointer;font-weight:500}
.seg input:checked+label{background:var(--surface-3);color:var(--fg);box-shadow:inset 0 0 0 1px #3a3a3a}
.seg input:focus-visible+label{outline:2px solid var(--accent-bright)}
.check{grid-column:1/-1;display:flex;gap:10px;align-items:flex-start;font-size:14px;color:var(--muted)}
.check input{accent-color:var(--accent);width:18px;height:18px;margin-top:2px;flex:none}
.result{background:linear-gradient(160deg,#0f2a0f,#0d140d 60%);border-left:1px solid var(--line);padding:clamp(20px,3vw,36px);display:flex;flex-direction:column;gap:22px}
.result .big span{display:block;font:500 12px/1 var(--f-mono);letter-spacing:.14em;text-transform:uppercase;color:var(--accent);margin-bottom:12px}
.result .big output{display:block;font:800 clamp(48px,6vw,76px)/.9 var(--f-display);letter-spacing:-.05em;color:var(--fg);font-variant-numeric:tabular-nums}
.result .big output small{font-size:.32em;letter-spacing:0;color:var(--muted);font-weight:600;margin-left:8px}
.result .big output.bad{color:var(--loss)}
.result dl{display:grid;gap:12px;border-top:1px solid rgba(255,255,255,.08);padding-top:20px}
.result dl div{display:flex;justify-content:space-between;gap:16px;font-size:15px}
.result dt{color:var(--muted)}
.result dd{font-family:var(--f-mono);font-variant-numeric:tabular-nums;text-align:right}
.result dd.bad{color:var(--loss)}
.result .msg{font-size:13.5px;color:var(--warn)}
.result .msg:empty{display:none}
.result .note{font-size:13px;color:var(--dim);margin-top:auto}
@media (max-width:860px){.tool{grid-template-columns:1fr}.result{border-left:0;border-top:1px solid var(--line)}}
@media (max-width:520px){.fields{grid-template-columns:1fr}}

/* Contenido */
section.block{padding-block:0 clamp(56px,8vw,96px)}
.two{display:grid;grid-template-columns:minmax(0,.8fr) minmax(0,1.2fr);gap:clamp(24px,5vw,64px)}
@media (max-width:860px){.two{grid-template-columns:1fr}}
.prose{display:flex;flex-direction:column;gap:16px;color:var(--muted);font-size:17px;max-width:64ch}
.prose strong{color:var(--fg)}
.formula{font:500 15px/1.6 var(--f-mono);color:var(--fg);background:var(--surface);border:1px solid var(--line);border-left:3px solid var(--accent);border-radius:12px;padding:16px 18px}
.example{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:16px 18px}
.example .tag{font:500 11px/1.4 var(--f-mono);letter-spacing:.14em;color:var(--dim);text-transform:uppercase;display:block;margin-bottom:8px}
.callout{font-size:14.5px;color:var(--warn);border:1px solid rgba(233,180,60,.35);background:rgba(233,180,60,.06);border-radius:12px;padding:12px 16px}
.faq details{border-bottom:1px solid var(--line)}
.faq summary{list-style:none;cursor:pointer;display:flex;justify-content:space-between;gap:16px;padding:20px 0;font:700 18px/1.3 var(--f-display);letter-spacing:-.02em}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";color:var(--accent);font-size:24px;line-height:1}
.faq details[open] summary::after{content:"−"}
.faq details p{padding:0 0 20px;color:var(--muted);max-width:68ch}
.more{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px}
.more a{display:flex;flex-direction:column;gap:6px;border:1px solid var(--line);border-radius:16px;padding:20px;text-decoration:none;background:var(--surface)}
.more a:hover{border-color:var(--accent)}
.more a[hidden]{display:none}
.more a span{color:var(--muted);font-size:14px}

/* Cierre con CTA (línea de la home) */
.closing{background:#88EF1B;color:#131313;border-radius:22px;padding:clamp(28px,5vw,56px);display:grid;grid-template-columns:1.2fr .8fr;gap:24px;align-items:center;margin-bottom:40px}
.closing h2{color:#131313;max-width:14ch}
.closing p{font-size:17px;max-width:46ch}
.closing .cta{display:flex;flex-direction:column;align-items:flex-start;gap:10px}
.closing .btn{background:#131313;color:#F0F0F0}
.closing small{font-size:13px}
@media (max-width:760px){.closing{grid-template-columns:1fr}}
footer{border-top:1px solid var(--line);padding-block:28px 48px;color:var(--dim);font-size:13px}
footer .wrap{display:flex;flex-direction:column;gap:10px}
footer nav{display:flex;flex-wrap:wrap;gap:6px 18px}footer nav a{text-decoration:none;color:var(--muted)}
.page[hidden]{display:none}

footer nav.foot-cols{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px;align-items:start;margin-block:12px}footer .foot-cols div{display:flex;flex-direction:column;gap:8px}footer .foot-cols b{font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--fg)}@media(max-width:560px){footer nav.foot-cols{grid-template-columns:1fr 1fr}}

.input textarea{resize:vertical;width:100%;line-height:1.5}