/*!
 * SciParaTodos · Propiedades de los Números Reales — estilos
 */
:root{
  --bg:#eef4fb; --bg2:#e3ecf7; --card:#fff; --tx:#10233f; --tx2:#4b5b72; --tx3:#6b7a90; --line:#dbe3ee;
  --acc:#6d4ae8; --acc2:#f1ecff; --red:#e5484d; --navy:#0f1c3a;
  --cK:#1586b5; --cU:#0f9f6e; --cQ:#e8833a; --cE:#6d4ae8; --cT:#10233f;
  --ok:#0f8a5f; --okbg:#e6f6ef; --warn:#b45309; --warnbg:#fff4e5; --bad:#c2410c; --badbg:#fff1ec;
  --r:18px; --mono:'JetBrains Mono',ui-monospace,Consolas,monospace;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--tx);font-family:'Nunito Sans',system-ui,-apple-system,'Segoe UI',Roboto,Arial,sans-serif;font-size:16px;line-height:1.55}
.wrap{max-width:1320px;margin:0 auto;padding:0 28px}
button,input,select{font:inherit;color:inherit}
a{color:var(--acc)}
img{max-width:100%}

/* ---------- navegación ---------- */
.nav{position:sticky;top:0;z-index:20;background:rgba(255,255,255,.92);backdrop-filter:saturate(1.4) blur(10px);-webkit-backdrop-filter:saturate(1.4) blur(10px);border-bottom:1px solid var(--line)}
.nav-in{display:flex;align-items:center;gap:20px;min-height:72px}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:var(--tx)}
.logo{height:52px;width:auto}
.logo.sm{height:36px}
.brand-tx{display:flex;flex-direction:column;line-height:1.25}
.brand-tx b{font-weight:800;font-size:15px}
.brand-tx small{color:var(--tx3);font-size:13px}
.links{display:flex;gap:4px;margin-left:auto}
.links a{text-decoration:none;color:var(--tx2);font-weight:700;font-size:15px;padding:8px 12px;border-radius:10px}
.links a:hover{background:var(--acc2);color:var(--acc)}
.lang{display:flex;gap:6px}
.lang button{min-width:44px;height:40px;border-radius:12px;border:1px solid var(--line);background:#fff;font-weight:800;cursor:pointer}
.lang button.on{background:var(--acc);color:#fff;border-color:var(--acc)}

/* ---------- hero ---------- */
.hero{position:relative;overflow:hidden;color:#fff;
  background:radial-gradient(1200px 500px at 85% 10%,rgba(109,74,232,.45),transparent 60%),
             radial-gradient(900px 500px at 0% 100%,rgba(21,134,181,.35),transparent 60%),
             linear-gradient(160deg,#0b1430 0%,#13224a 55%,#1b2f63 100%)}
.hero-in{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.05fr);gap:34px;align-items:center;padding:64px 28px 72px}
.tag{display:inline-block;background:rgba(255,255,255,.12);border:1px solid rgba(255,255,255,.22);padding:6px 14px;border-radius:999px;font-weight:700;font-size:13px;letter-spacing:.04em}
.hero h1{font-size:clamp(32px,5vw,56px);line-height:1.06;margin:18px 0 16px;font-weight:900;letter-spacing:-.01em}
.hero .lead{font-size:18px;color:#d6def0;margin:0 0 16px;max-width:620px}
.hero .lead b{color:#fff}
.autores{margin:0 0 26px;font-weight:700;color:#bcc8e4;font-size:15px}
.cta{display:flex;flex-wrap:wrap;gap:12px}
.chips{list-style:none;display:flex;flex-wrap:wrap;gap:10px;padding:0;margin:26px 0 0}
.chips li{font-size:14px;font-weight:700;color:#d6def0;background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.14);padding:6px 12px;border-radius:10px}
.hero-img img{display:block;width:100%;height:auto;border-radius:22px;box-shadow:0 30px 60px -20px rgba(0,0,0,.55),0 0 0 1px rgba(255,255,255,.08)}

/* ---------- botones ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:1px solid var(--line);background:#fff;border-radius:12px;padding:10px 16px;font-weight:800;cursor:pointer;text-decoration:none;color:var(--tx);transition:transform .08s,box-shadow .15s}
.btn:hover{box-shadow:0 4px 14px -6px rgba(16,35,63,.35)}
.btn:active{transform:translateY(1px)}
.btn.pri{background:var(--acc);border-color:var(--acc);color:#fff}
.btn.ghost{background:transparent;border-color:rgba(255,255,255,.4);color:#fff}
.btn.big{padding:14px 22px;font-size:17px;border-radius:14px}

/* ---------- secciones ---------- */
.sec{padding:72px 0}
.sec.alt{background:var(--bg2)}
.sh{max-width:760px;margin:0 0 30px}
.stag{color:#1a7fa3;font-weight:900;letter-spacing:.14em;text-transform:uppercase;font-size:13px}
.sh h2{font-size:clamp(26px,3.4vw,38px);line-height:1.15;margin:6px 0 8px;font-weight:900}
.sh p{margin:0;color:var(--tx2)}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:22px;box-shadow:0 1px 2px rgba(16,35,63,.04)}
.card h3{margin:0 0 14px;font-size:19px;font-weight:900}

/* ---------- laboratorio ---------- */
.lab{display:grid;grid-template-columns:minmax(0,1fr) 340px;gap:20px;align-items:start}
.escena{padding:14px}
.lienzo{position:relative;border-radius:14px;overflow:hidden;background:#bfe3fa}
#cv{display:block;width:100%;height:auto;aspect-ratio:2/1}
.reloj{position:absolute;top:12px;right:12px;font-family:var(--mono);font-weight:700;font-size:clamp(16px,2.4vw,26px);color:#fff;background:rgba(15,28,58,.82);padding:6px 14px;border-radius:12px;letter-spacing:.06em}
.estado{position:absolute;top:12px;left:12px;font-size:13px;font-weight:800;color:#fff;background:rgba(15,28,58,.7);padding:5px 11px;border-radius:999px}
.mensaje{position:absolute;left:12px;right:12px;bottom:12px;font-weight:700;font-size:14px;border-radius:12px;padding:10px 14px;display:none}
.mensaje.ok{display:block;background:rgba(230,246,239,.96);color:#0b5c40}
.mensaje.info{display:block;background:rgba(255,255,255,.95);color:var(--tx)}
.mensaje.bad{display:block;background:rgba(255,241,236,.97);color:#9a3412}
.lecturas{display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:8px;margin-top:12px}
.lecturas div{background:#f4f7fb;border-radius:12px;padding:8px 10px;min-width:0}
.lecturas span{display:block;font-size:12px;color:var(--tx3);font-weight:700;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.lecturas b{font-family:var(--mono);font-size:15px;white-space:nowrap}

.panel{background:linear-gradient(180deg,#14234a,#0f1c3a);color:#e6ecf8;border-color:#1f3263}
.panel h3{color:#fff;margin:0}
.panel-h{display:flex;justify-content:space-between;align-items:center;margin-bottom:14px}
.badge{font-size:11px;font-weight:900;letter-spacing:.08em;text-transform:uppercase;background:rgba(255,255,255,.14);padding:4px 10px;border-radius:999px}
.badge.run{background:#0f9f6e;color:#fff}
.badge.end{background:#6d4ae8;color:#fff}
.botones{display:grid;grid-template-columns:1fr 48px;gap:8px}
.botones .btn{padding:11px}
#b-play{background:#fff;color:var(--navy);border-color:#fff}
#b-reset{background:transparent;color:#fff;border-color:rgba(255,255,255,.3);font-size:18px}
.vel{display:grid;grid-template-columns:repeat(4,1fr);gap:4px;margin:10px 0 14px;background:rgba(255,255,255,.06);padding:4px;border-radius:12px}
.vel button{border:0;background:transparent;color:#c9d5ea;font-weight:800;border-radius:9px;padding:6px 0;cursor:pointer}
.vel button.on{background:#fff;color:var(--navy)}
.campo{display:block;margin:0 0 12px}
.campo span{display:block;font-size:13px;font-weight:700;margin-bottom:5px;color:#c9d5ea}
.campo select{width:100%;padding:9px 10px;border-radius:10px;border:1px solid rgba(255,255,255,.18);background:#1b2c57;color:#fff}
.desl{margin:0 0 10px;padding-top:8px;border-top:1px solid rgba(255,255,255,.08)}
.dl-h{display:flex;justify-content:space-between;font-size:13px;font-weight:700;color:#c9d5ea}
.dl-h b{color:#7ee2b8;font-family:var(--mono);font-size:13px}
.desl input{width:100%;accent-color:#8f74ff;margin:6px 0 0}
.chks{display:flex;flex-wrap:wrap;gap:8px 14px;margin:8px 0 6px}
.chk{display:flex;align-items:center;gap:6px;font-size:14px;font-weight:700;cursor:pointer}
.chk input{width:16px;height:16px;accent-color:#8f74ff}
.hmin{font-size:13px;color:#c9d5ea;margin:8px 0 0;background:rgba(255,255,255,.06);border-radius:10px;padding:8px 10px}
.hmin b{color:#fff}

.izq{display:grid;gap:20px;min-width:0}
.lab2{display:grid;grid-template-columns:minmax(0,1fr);gap:20px;margin-top:20px}

.barras{display:flex;flex-direction:column;gap:10px}
.barra{display:grid;grid-template-columns:150px minmax(0,1fr) 96px;gap:10px;align-items:center;font-size:14px}
.barra .nm{font-weight:700;color:var(--tx2)}
.barra .tr{height:16px;background:#eef2f8;border-radius:999px;overflow:hidden}
.barra .fl{height:100%;border-radius:999px;transition:width .05s linear}
.barra .vl{font-family:var(--mono);font-size:13px;text-align:right}
.nota{color:var(--tx2);font-size:14px;margin:12px 0 0}
.tabs{display:flex;flex-wrap:wrap;gap:6px;margin-bottom:12px}
.tabs button{border:1px solid var(--line);background:#fff;border-radius:999px;padding:6px 14px;font-weight:800;font-size:14px;cursor:pointer;color:var(--tx2)}
.tabs button.on{background:var(--acc);border-color:var(--acc);color:#fff}
.graf{display:block;width:100%}

.leyenda{display:flex;flex-wrap:wrap;gap:14px;font-size:13px;margin-top:6px}
.leyenda i{display:inline-block;width:18px;height:3px;border-radius:2px;vertical-align:middle;margin-right:5px}

.pred{margin-top:20px}
.formulas{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:12px}
.formulas div{background:var(--acc2);color:#3b2a8f;font-weight:700;font-size:14px;border-radius:10px;padding:6px 12px}
.tscroll{overflow-x:auto}
.pred table{width:100%;border-collapse:collapse;font-size:14px;min-width:720px}
.pred th,.pred td{padding:9px 8px;border-bottom:1px solid var(--line);text-align:right;white-space:nowrap}
.pred th:first-child,.pred td:first-child{text-align:left}
.pred th{background:#f4f7fb;font-weight:800}
.pred td{font-family:var(--mono);font-size:13px}
.pred td:first-child{font-family:inherit;font-size:14px;font-weight:700}
.pred td.ok{color:var(--ok)}
.pred td.muted{color:var(--tx3)}
.acts{display:flex;flex-wrap:wrap;gap:10px;margin-top:14px}
.foot{color:var(--tx3);font-size:13px;margin:18px 0 0}

/* ---------- teoría ---------- */
.cards3{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}
.tc{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:22px}
.tc h3{margin:12px 0 8px;font-size:18px;font-weight:900}
.tc p{margin:0;color:var(--tx2)}
.tc p b{color:var(--tx)}
.ico{width:46px;height:46px;border-radius:14px;display:grid;place-items:center;font-weight:900;font-size:20px;color:#fff;background:linear-gradient(135deg,var(--acc),#1586b5);font-style:italic}
.figs{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:18px}
.figs figure{margin:0}
.figs svg{width:100%;height:auto;display:block}
.figs figcaption{color:var(--tx2);font-size:14px;margin-top:8px}

/* ---------- actividades ---------- */
.act .ac{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:22px;display:flex;flex-direction:column}
.ac .num{font-weight:900;color:var(--acc);font-size:13px;letter-spacing:.1em}
.ac h3{margin:4px 0 12px;font-size:18px;font-weight:900}
.ac h4{margin:10px 0 6px;font-size:14px;font-weight:900;color:var(--tx2);text-transform:uppercase;letter-spacing:.06em}
.ac ol,.ac ul{margin:0;padding-left:20px;color:var(--tx2)}
.ac li{margin:3px 0}
.ac .btn{margin-top:auto;align-self:flex-start}
.ac .esp{flex:1;min-height:14px}

/* ---------- preguntas ---------- */
.faq{display:grid;gap:12px;max-width:900px}
.faq details{background:#fff;border:1px solid var(--line);border-radius:14px;padding:16px 20px}
.faq summary{font-weight:800;cursor:pointer;font-size:17px}
.faq p{margin:10px 0 0;color:var(--tx2)}

/* ---------- pie ---------- */
.ft{background:var(--navy);color:#c9d5e4;padding:40px 0 28px}
.ft-in{display:grid;grid-template-columns:1fr auto;gap:20px}
.ft .brand{color:#fff}
.ft p{margin:10px 0 0;max-width:460px;font-size:14px}
.ft-links{display:flex;flex-wrap:wrap;gap:16px;align-items:flex-start}
.ft-links a{color:#fff;text-decoration:none;font-weight:700;font-size:14px}
.copy{grid-column:1/-1;border-top:1px solid rgba(255,255,255,.12);padding-top:16px;font-size:13px}

/* ---------- responsivo ---------- */
@media (max-width:1100px){
  .lab{grid-template-columns:minmax(0,1fr)}
  .lab2{grid-template-columns:minmax(0,1fr)}
  .lecturas{grid-template-columns:repeat(3,minmax(0,1fr))}
}
@media (max-width:900px){
  .hero-in{grid-template-columns:minmax(0,1fr);padding:44px 28px 52px}
  .cards3{grid-template-columns:repeat(2,minmax(0,1fr))}
  .figs{grid-template-columns:minmax(0,1fr)}
  .links{display:none}
  .lang{margin-left:auto}
}
@media (max-width:600px){
  .wrap{padding:0 16px}
  .hero-in{padding:36px 16px 44px}
  .cards3{grid-template-columns:minmax(0,1fr)}
  .lecturas{grid-template-columns:repeat(2,minmax(0,1fr))}
  .barra{grid-template-columns:110px minmax(0,1fr) 84px;font-size:13px}
  .sec{padding:52px 0}
  .card{padding:16px}
  .ft-in{grid-template-columns:minmax(0,1fr)}
  .logo{height:42px}
  .reloj{font-size:13px;padding:3px 8px;top:6px;right:6px}
  .estado{display:none}
  .mensaje{font-size:12px;padding:6px 9px;left:6px;right:6px;bottom:6px}
  .escena{padding:8px}
}

/* ---------- plano inclinado ---------- */
.dos-col{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:20px}
.fuerzas{width:100%;border-collapse:collapse;font-size:14px}
.fuerzas td{padding:7px 4px;border-bottom:1px solid var(--line)}
.fuerzas td.num{font-family:var(--mono);font-size:13px;text-align:right;white-space:nowrap}
.fuerzas td.dir{color:var(--tx3);font-size:12px;text-align:right;white-space:nowrap;padding-left:8px}
.fuerzas tr.net td{font-weight:800;border-bottom:0;background:var(--acc2)}
.dos-col .barra{grid-template-columns:118px minmax(0,1fr) 78px;font-size:13px}
.pred td.frm{font-family:inherit;font-size:13px;color:#3b2a8f;text-align:left}
.pred table{min-width:640px}
.lecturas b{font-size:14px}
@media (max-width:1300px){ .dos-col{grid-template-columns:minmax(0,1fr)} }
.pred th:nth-child(2){text-align:left}
@media (max-width:600px){.lienzo .mensaje{position:static;border-radius:0}}

/* ---------- números reales ---------- */
.det{padding:26px}
.ecuacion{display:grid;grid-template-columns:minmax(0,1fr) auto minmax(0,1fr);gap:14px;align-items:end}
.campo-exp{display:block}
.campo-exp span{display:block;font-weight:800;font-size:14px;margin-bottom:6px;color:var(--tx2)}
.campo-exp input{width:100%;font-family:var(--mono);font-size:22px;padding:14px 16px;border:2px solid var(--line);border-radius:14px;background:#fff;outline:none}
.campo-exp input:focus{border-color:var(--acc);box-shadow:0 0 0 4px var(--acc2)}
.campo-exp input.malo{border-color:var(--bad);background:#fff6f2}
.igual{font-size:38px;font-weight:900;color:var(--acc);padding-bottom:8px}
.teclado{display:flex;flex-wrap:wrap;gap:6px;margin-top:14px}
.teclado button{min-width:44px;height:40px;border-radius:10px;border:1px solid var(--line);background:#f4f7fb;font-family:var(--mono);font-size:17px;font-weight:700;cursor:pointer}
.teclado button:hover{background:var(--acc2);border-color:#c9b8f5}
.teclado .borrar{font-family:inherit;font-size:14px;padding:0 14px;color:var(--bad);margin-left:auto}
.ejemplos{display:flex;flex-wrap:wrap;align-items:center;gap:8px;margin-top:14px}
.ejemplos>span{font-weight:800;font-size:14px;color:var(--tx2)}
.ejemplos>div{display:flex;flex-wrap:wrap;gap:6px}
.ej{border:1px solid var(--line);background:#fff;border-radius:999px;padding:5px 12px;font-family:var(--mono);font-size:13px;cursor:pointer;color:var(--tx)}
.ej:hover{border-color:var(--acc);color:var(--acc)}
.ayuda2{color:var(--tx3);font-size:13px;margin:12px 0 0}
.resultado{margin-top:18px}
.rc{border-radius:var(--r);padding:24px;border:1px solid var(--line);background:#fff;box-shadow:0 1px 2px rgba(16,35,63,.04)}
.rc.ok{border-color:#a7e3c8;background:linear-gradient(180deg,#f0fbf6,#fff 120px)}
.rc.bad{border-color:#f5c2b0;background:linear-gradient(180deg,#fff4ef,#fff 120px)}
.rc.info{border-color:#f3dcae;background:linear-gradient(180deg,#fff9ec,#fff 120px)}
.rc .eti{font-size:13px;font-weight:900;letter-spacing:.1em;text-transform:uppercase;color:var(--tx3)}
.rc h3{margin:6px 0 10px;font-size:clamp(22px,3vw,30px);font-weight:900}
.rc.ok h3{color:#0b5c40}.rc.bad h3{color:#9a3412}
.igualdad{font-family:var(--mono);font-size:clamp(17px,2.4vw,22px);background:#f4f7fb;border-radius:12px;padding:12px 16px;margin:8px 0 14px;overflow-x:auto;white-space:nowrap}
.igualdad .eq{color:var(--acc);font-weight:900;padding:0 8px}
mark.hl{background:#ffe58f;color:inherit;border-radius:5px;padding:1px 3px;box-shadow:0 0 0 2px #ffd43b inset}
.formula{display:inline-block;font-family:var(--mono);font-weight:700;background:var(--acc2);color:#3b2a8f;border-radius:10px;padding:6px 12px;margin:2px 0 10px}
.rc p{margin:6px 0;color:var(--tx2)}
.nota-c{font-size:13px;color:var(--warn);font-weight:700}
.pasos{list-style:none;margin:10px 0 0;padding:0;display:grid;gap:10px}
.pasos li{border:1px solid var(--line);border-radius:14px;padding:12px 14px;background:#fff}
.pasos .ph{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-bottom:6px}
.pasos .nro{width:26px;height:26px;border-radius:50%;background:var(--acc);color:#fff;display:grid;place-items:center;font-weight:900;font-size:13px}
.pasos .pn{font-weight:900}
.pasos .pf{font-family:var(--mono);font-size:12px;color:#3b2a8f;background:var(--acc2);border-radius:8px;padding:2px 8px}
.pasos .pe{font-family:var(--mono);font-size:16px;overflow-x:auto;white-space:nowrap}
.pasos .flecha{color:var(--acc);font-weight:900;padding:0 8px}
.pasos .inv{font-size:12px;color:var(--tx3)}
/* práctica */
.pra{padding:26px}
.pra-top{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}
.marcador{font-weight:700;color:var(--tx2)}
.marcador b{color:var(--tx);font-family:var(--mono)}
.seg{display:flex;gap:4px;background:#f4f7fb;border-radius:12px;padding:4px}
.seg button{border:0;background:transparent;border-radius:9px;padding:7px 12px;font-weight:800;font-size:14px;cursor:pointer;color:var(--tx2)}
.seg button.on{background:var(--acc);color:#fff}
.pra-exp{font-family:var(--mono);font-size:clamp(22px,3.4vw,34px);font-weight:700;text-align:center;padding:26px 10px;margin:16px 0 4px;background:#f4f7fb;border-radius:16px;overflow-x:auto;white-space:nowrap}
.pra-exp .eq{color:var(--acc);padding:0 12px}
.pra-q{text-align:center;font-weight:800;margin:10px 0 14px}
.opciones{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
.opciones button{border:2px solid var(--line);background:#fff;border-radius:14px;padding:14px;font-weight:800;font-size:15px;cursor:pointer;text-align:left;color:var(--tx)}
.opciones button:hover:not(:disabled){border-color:var(--acc)}
.opciones button.si{border-color:var(--ok);background:var(--okbg);color:#0b5c40}
.opciones button.no{border-color:var(--bad);background:var(--badbg);color:#9a3412}
.opciones button:disabled{cursor:default}
.pra-fb{min-height:24px;text-align:center;font-weight:800;margin-top:12px}
.pra-fb.si{color:var(--ok)}.pra-fb.no{color:var(--bad)}
/* clasificador */
.cla{display:grid;grid-template-columns:minmax(0,5fr) minmax(0,6fr);gap:20px;align-items:start}
.cla-res{margin-top:16px}
.cla-val{font-family:var(--mono);font-size:15px;color:var(--tx2);margin:0 0 10px}
.conj{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:8px}
.conj div{border-radius:12px;padding:10px 6px;text-align:center;font-weight:900;border:2px solid var(--line);background:#fff}
.conj div small{display:block;font-weight:700;font-size:11px;margin-top:2px}
.conj div.si{background:var(--okbg);border-color:#9fdcc0;color:#0b5c40}
.conj div.no{color:var(--tx3);background:#f8fafd}
.cla-m{margin:12px 0 0;color:var(--tx2)}
.cla-err{color:var(--bad);font-weight:700}
#venn{width:100%;height:auto;display:block}
#venn rect{fill:#fff;stroke:#8fa3bd;stroke-width:2;transition:fill .2s}
#venn .v-R{fill:#f4f7fb}
#venn .v-t{font:900 18px 'Nunito Sans',sans-serif;fill:#10233f}
#venn .v-s{font:700 12px 'Nunito Sans',sans-serif;fill:#4b5b72}
#venn .v-ej text{font:600 14px 'JetBrains Mono',monospace;fill:#8fa3bd}
#venn[data-set="N"] .v-N,#venn[data-set="Z"] .v-Z,#venn[data-set="Q"] .v-Q,#venn[data-set="I"] .v-I{fill:#e6f6ef;stroke:#0f8a5f;stroke-width:3}
#venn[data-set="N"] .v-Z,#venn[data-set="N"] .v-Q,#venn[data-set="Z"] .v-Q{fill:#f3fbf7}
#v-pto{fill:#e5484d;stroke:#fff;stroke-width:3;transition:cx .25s,cy .25s}
/* referencia */
.props .pc{background:#fff;border:1px solid var(--line);border-radius:var(--r);padding:20px}
.props .pc h3{margin:0 0 8px;font-size:17px;font-weight:900}
.props .pc .formula{font-size:14px}
.props .pc p{margin:4px 0;color:var(--tx2);font-size:14px}
.props .pc .ejm{font-family:var(--mono);font-size:13px;color:var(--tx)}
@media (max-width:900px){ .cla{grid-template-columns:minmax(0,1fr)} }
@media (max-width:640px){
  .ecuacion{grid-template-columns:minmax(0,1fr)}
  .igual{padding:0;text-align:center;font-size:28px}
  .opciones{grid-template-columns:minmax(0,1fr)}
  .conj{grid-template-columns:repeat(3,minmax(0,1fr))}
  .campo-exp input{font-size:18px}
}