/* MateKids — estilos. Claro y oscuro por variables. */
:root{
  --bg:#f6f4ee; --surface:#fffdf8; --surface-2:#eeebe1;
  --ink:#27261f; --ink-soft:#5c5a50; --ink-faint:#8b887b;
  --line:#e3dfd2; --line-strong:#cbc5b2;
  --brand:#1d6e56; --brand-soft:#dff0e8; --brand-ink:#0f4b3a;
  --accent:#c65a2e; --accent-soft:#fae9df; --accent-ink:#8a3d1d;
  --gold:#b8862a; --gold-soft:#f6ecd4;
  --b1:#1d6e56; --b1s:#dff0e8; --b2:#2b6ca3; --b2s:#e1edf8; --b3:#8a4fa8; --b3s:#efe5f6;
  --ok:#1d7a4d; --ok-soft:#dcf2e4; --bad:#c0392b; --bad-soft:#fbe4e1;
  --radius:16px; --shadow:0 6px 24px rgba(40,35,20,.08);
  --font-head:"Fraunces",Georgia,serif; --font-body:"Figtree","Segoe UI",system-ui,sans-serif;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#17160f; --surface:#211f16; --surface-2:#2b281d;
  --ink:#f1eee4; --ink-soft:#c2beb0; --ink-faint:#8f8b7e;
  --line:#37342a; --line-strong:#4a4638;
  --brand:#4fc49c; --brand-soft:#173a2e; --brand-ink:#a4e4cf;
  --accent:#ea8c60; --accent-soft:#3b2117; --accent-ink:#f3bc9f;
  --gold:#d8ab51; --gold-soft:#352c16;
  --b1:#4fc49c; --b1s:#173a2e; --b2:#5fa9e2; --b2s:#142b3f; --b3:#c393dc; --b3s:#2d1d3a;
  --ok:#5fcc8f; --ok-soft:#163528; --bad:#ea746c; --bad-soft:#3b1d1a;
  --shadow:0 6px 24px rgba(0,0,0,.35);
  color-scheme:dark;
}}
:root[data-theme="dark"]{
  --bg:#17160f; --surface:#211f16; --surface-2:#2b281d;
  --ink:#f1eee4; --ink-soft:#c2beb0; --ink-faint:#8f8b7e;
  --line:#37342a; --line-strong:#4a4638;
  --brand:#4fc49c; --brand-soft:#173a2e; --brand-ink:#a4e4cf;
  --accent:#ea8c60; --accent-soft:#3b2117; --accent-ink:#f3bc9f;
  --gold:#d8ab51; --gold-soft:#352c16;
  --b1:#4fc49c; --b1s:#173a2e; --b2:#5fa9e2; --b2s:#142b3f; --b3:#c393dc; --b3s:#2d1d3a;
  --ok:#5fcc8f; --ok-soft:#163528; --bad:#ea746c; --bad-soft:#3b1d1a;
  --shadow:0 6px 24px rgba(0,0,0,.35);
  color-scheme:dark;
}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--font-body);line-height:1.55;font-size:15.5px;min-height:100vh}
button{font-family:inherit;font-size:inherit;color:inherit}
a{color:var(--brand)}
.wrap{max-width:760px;margin:0 auto;padding:0 max(16px,env(safe-area-inset-left)) 90px max(16px,env(safe-area-inset-right))}
[hidden]{display:none!important}

/* ---------- barra superior ---------- */
.topbar{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.topbar .in{max-width:760px;margin:0 auto;display:flex;align-items:center;gap:10px;padding:10px 16px;min-height:56px}
.brand{display:flex;align-items:center;gap:9px;text-decoration:none;color:var(--ink);font-family:var(--font-head);font-weight:600;font-size:19px;letter-spacing:-.01em}
.brand .logo{width:32px;height:32px;border-radius:9px;background:var(--brand);color:#fff;display:grid;place-items:center;font-size:17px;font-family:var(--font-head)}
.spacer{flex:1}
.ibtn{width:38px;height:38px;border-radius:10px;border:1px solid var(--line);background:var(--surface);display:grid;place-items:center;cursor:pointer;font-size:17px;transition:.15s}
.ibtn:hover{border-color:var(--brand)}
.streak-pill{display:inline-flex;align-items:center;gap:5px;background:var(--accent-soft);color:var(--accent-ink);border-radius:99px;padding:5px 11px;font-weight:700;font-size:13.5px}
.user-pill{display:inline-flex;align-items:center;gap:6px;background:var(--surface);border:1px solid var(--line);border-radius:99px;padding:5px 10px 5px 6px;font-size:13.5px;font-weight:600;cursor:pointer}
.user-pill .av{width:24px;height:24px;border-radius:50%;background:var(--b3);color:#fff;display:grid;place-items:center;font-size:12px}

/* ---------- tipografía ---------- */
h1{font-family:var(--font-head);font-weight:600;font-size:30px;line-height:1.08;margin:0 0 8px;letter-spacing:-.01em;text-wrap:balance}
h2{font-family:var(--font-head);font-weight:600;font-size:24px;line-height:1.12;margin:0 0 6px;letter-spacing:-.01em;text-wrap:balance}
h3{font-size:16px;margin:0 0 8px}
.kicker{font-size:12px;letter-spacing:.13em;text-transform:uppercase;color:var(--brand);font-weight:700;margin:0 0 6px}
.sub{color:var(--ink-soft);margin:0}
.muted{color:var(--ink-faint)}
.small{font-size:13px}
b.hl{color:var(--accent-ink);background:var(--accent-soft);padding:1px 6px;border-radius:6px;font-weight:700}
.mathline{font-family:var(--font-head);font-size:1.1em;background:var(--surface-2);border-radius:8px;padding:3px 10px;display:inline-block;margin:2px 0;font-variant-numeric:tabular-nums;white-space:nowrap}
.card p{margin:0 0 10px}.card p:last-child{margin-bottom:0}
.card ul{margin:6px 0 0;padding-left:20px}.card li{margin-bottom:6px}
.lead{font-size:17px}

/* fracciones apiladas */
.fr{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;line-height:1.05;margin:0 3px;font-variant-numeric:tabular-nums;font-size:.92em}
.fr .fr-n{border-bottom:1.6px solid currentColor;padding:0 4px 1px}
.fr .fr-d{padding:1px 4px 0}
.fr .fr-sign{position:absolute;margin-left:-14px;margin-top:9px}
.fr-mix{display:inline-flex;align-items:center;gap:2px}
.fr-int{font-variant-numeric:tabular-nums}
.mathline .fr{font-size:.95em}

/* ---------- tarjetas ---------- */
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px;margin:14px 0}
.card.flat{box-shadow:none}
.card .ct{font-size:12.5px;font-weight:800;letter-spacing:.08em;text-transform:uppercase;margin:0 0 10px;display:flex;align-items:center;gap:8px}
.card.idea .ct{color:var(--brand)}
.card.trick{background:var(--accent-soft);border-color:color-mix(in srgb,var(--accent) 50%,transparent)}
.card.trick .ct{color:var(--accent-ink)}
.card.trick b{color:var(--accent-ink)}
.card.ex .ct{color:var(--gold)}
.ex-step{display:flex;gap:12px;padding:9px 0;border-bottom:1px dashed var(--line)}
.ex-step:last-child{border-bottom:none;padding-bottom:0}
.ex-step .n{flex:none;width:24px;height:24px;border-radius:50%;background:var(--gold-soft);color:var(--gold);font-weight:800;font-size:12.5px;display:grid;place-items:center;font-family:var(--font-head)}
figure.draw{margin:12px 0 4px;text-align:center}
figure.draw svg{max-width:100%;height:auto}
figure.draw figcaption{font-size:12.5px;color:var(--ink-faint);margin-top:6px}
svg.dw{overflow:visible}
.dtable{border-collapse:collapse;margin:8px auto;font-variant-numeric:tabular-nums}
.dtable th,.dtable td{border:1px solid var(--line-strong);padding:6px 12px;text-align:center}
.dtable th{background:var(--surface-2);font-size:13px}
.dtable tr.hl td{background:var(--accent-soft);font-weight:700}

/* ---------- botones ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;font-weight:700;font-size:15px;color:#fff;background:var(--brand);border:none;border-radius:12px;padding:12px 20px;cursor:pointer;transition:.15s;text-decoration:none;line-height:1.2}
.btn:hover{filter:brightness(1.07)}.btn:active{transform:scale(.98)}
.btn:disabled{opacity:.45;cursor:default;transform:none}
.btn.ghost{background:transparent;color:var(--brand);border:1.5px solid var(--brand)}
.btn.soft{background:var(--brand-soft);color:var(--brand-ink)}
.btn.accent{background:var(--accent)}
.btn.big{font-size:17px;padding:16px 24px;border-radius:14px;width:100%}
.btn.sm{font-size:13.5px;padding:8px 14px;border-radius:9px}
.btn.wide{width:100%}
.row{display:flex;gap:10px;flex-wrap:wrap;align-items:center}
.row.between{justify-content:space-between}
.row.center{justify-content:center}
.back{display:inline-flex;align-items:center;gap:7px;background:none;border:none;color:var(--brand);font-weight:700;cursor:pointer;padding:12px 0 8px;font-size:14.5px}
.back:hover{text-decoration:underline}

/* ---------- inicio ---------- */
.hero{padding:22px 0 10px}
.today{background:linear-gradient(135deg,var(--brand),#2b8f70);color:#fff;border-radius:20px;padding:20px;margin:14px 0;box-shadow:var(--shadow);position:relative;overflow:hidden}
.today::after{content:"";position:absolute;right:-30px;top:-30px;width:140px;height:140px;border-radius:50%;background:rgba(255,255,255,.08)}
.today h2{color:#fff;margin:0 0 4px}
.today p{margin:0 0 14px;opacity:.92}
.today .btn{background:#fff;color:var(--brand-ink)}
.today .streak{display:inline-flex;gap:6px;align-items:center;font-weight:800;background:rgba(255,255,255,.18);padding:5px 11px;border-radius:99px;font-size:13.5px;margin-bottom:10px}
.today.done{background:linear-gradient(135deg,#4e6b86,#6a5c90)}
.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin:14px 0}
.stat{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:12px;text-align:center}
.stat .v{font-family:var(--font-head);font-size:24px;font-weight:600;line-height:1}
.stat .l{font-size:12px;color:var(--ink-faint);margin-top:4px}
.bloque{margin:22px 0}
.bloque-h{display:flex;align-items:center;gap:12px;padding:12px 14px;border-radius:14px;border:1px solid var(--line);margin-bottom:12px;cursor:pointer}
.bloque-h .bn{font-family:var(--font-head);font-weight:600;font-size:20px;width:36px;height:36px;border-radius:10px;display:grid;place-items:center;color:#fff;flex:none}
.bloque-h .bt{font-weight:700;font-size:16px;line-height:1.15}
.bloque-h .bd{font-size:12.5px;color:var(--ink-faint)}
.bloque-h .bp{margin-left:auto;text-align:right;font-size:12.5px;color:var(--ink-soft);white-space:nowrap}
.b1 .bn{background:var(--b1)} .b1.bloque-h{background:var(--b1s)}
.b2 .bn{background:var(--b2)} .b2.bloque-h{background:var(--b2s)}
.b3 .bn{background:var(--b3)} .b3.bloque-h{background:var(--b3s)}
.pbar{height:8px;background:var(--surface-2);border-radius:99px;overflow:hidden;border:1px solid var(--line)}
.pbar i{display:block;height:100%;background:var(--brand);border-radius:99px;transition:width .5s ease}
.pbar.b2 i{background:var(--b2)}.pbar.b3 i{background:var(--b3)}
.topics{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}
@media(max-width:480px){.topics{grid-template-columns:1fr}}
.topic{position:relative;text-align:left;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:13px 14px 12px;cursor:pointer;transition:.16s;display:flex;flex-direction:column;gap:4px;min-height:92px}
.topic:hover{border-color:var(--brand);transform:translateY(-2px)}
.topic .tnum{font-family:var(--font-head);font-size:12px;color:var(--gold);font-weight:600}
.topic .ttl{font-size:14.5px;font-weight:700;line-height:1.25;padding-right:26px}
.topic .tdesc{font-size:12px;color:var(--ink-faint);line-height:1.35}
.topic .lv{display:flex;gap:4px;margin-top:auto;padding-top:6px;align-items:center}
.topic .lv i{width:18px;height:6px;border-radius:99px;background:var(--surface-2);border:1px solid var(--line)}
.topic .lv i.on{background:var(--brand);border-color:var(--brand)}
.topic .lv .ex{margin-left:6px;font-size:11px;color:var(--ink-faint);font-weight:700}
.topic .lv .ex.ok{color:var(--gold)}
.topic .medal{position:absolute;top:10px;right:10px;font-size:18px;line-height:1}
.topic.locked{opacity:.95}
.bloque-exam{margin-top:12px;display:flex;align-items:center;gap:12px;background:var(--surface);border:1px dashed var(--line-strong);border-radius:14px;padding:12px 14px}
.bloque-exam .t{font-weight:700;font-size:14px}
.bloque-exam .d{font-size:12.5px;color:var(--ink-faint)}

/* ---------- ficha ---------- */
.lhead{padding:6px 0 4px}
.lhead .tnum{font-family:var(--font-head);font-size:13.5px;color:var(--gold);font-weight:600}
.levels{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin:12px 0}
.level{background:var(--surface);border:1.5px solid var(--line);border-radius:14px;padding:14px 10px;text-align:center;cursor:pointer;transition:.15s;position:relative}
.level:hover{border-color:var(--brand)}
.level.locked{cursor:not-allowed;opacity:.6}
.level.locked:hover{border-color:var(--line)}
.level.done{border-color:var(--brand);background:var(--brand-soft)}
.level .ln{font-size:12px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-faint);font-weight:800}
.level .lt{font-size:16px;font-weight:800;margin:2px 0}
.level .ls{font-size:12px;color:var(--ink-soft)}
.level .lk{font-size:20px}
@media(max-width:420px){.levels{grid-template-columns:1fr}}
.examcard{display:flex;align-items:center;gap:14px;background:var(--gold-soft);border:1px solid color-mix(in srgb,var(--gold) 50%,transparent);border-radius:14px;padding:14px 16px;margin:12px 0}
.examcard .ic{font-size:28px}
.examcard .t{font-weight:800}
.examcard .d{font-size:13px;color:var(--ink-soft)}
.examcard.locked{opacity:.65}

/* ---------- ejercicios ---------- */
.session-top{display:flex;align-items:center;gap:12px;padding:12px 0 6px}
.session-top .name{font-weight:800;font-size:14px}
.session-top .cnt{margin-left:auto;font-size:13px;color:var(--ink-faint);font-variant-numeric:tabular-nums}
.dots{display:flex;gap:4px;margin:4px 0 10px}
.dots i{flex:1;height:6px;border-radius:99px;background:var(--surface-2);border:1px solid var(--line)}
.dots i.ok{background:var(--ok);border-color:var(--ok)}.dots i.bad{background:var(--bad);border-color:var(--bad)}.dots i.cur{background:var(--brand-soft);border-color:var(--brand)}
.qcard{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:20px 18px;margin:8px 0;animation:pop .25s ease}
@keyframes pop{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}
.qtext{font-size:18px;font-weight:700;margin:0 0 6px;line-height:1.4}
.qsub{font-size:13.5px;color:var(--ink-faint);margin:0 0 14px}
.qsvg{text-align:center;margin:6px 0 14px}
.qsvg svg{max-width:100%;height:auto}
.numin{width:100%;font-family:var(--font-head);font-size:22px;text-align:center;padding:13px;border:1.5px solid var(--line-strong);border-radius:12px;background:var(--surface);color:var(--ink);font-variant-numeric:tabular-nums}
.numin:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 4px var(--brand-soft)}
.numin.ok{border-color:var(--ok)}.numin.bad{border-color:var(--bad)}
.inhint{font-size:12px;color:var(--ink-faint);text-align:center;margin-top:6px}
.opts{display:grid;gap:9px}
.opts.grid2{grid-template-columns:1fr 1fr}
.opt{text-align:left;font-size:17px;padding:13px 15px;border:1.5px solid var(--line-strong);border-radius:12px;background:var(--surface);color:var(--ink);cursor:pointer;transition:.13s;font-variant-numeric:tabular-nums;display:flex;align-items:center;gap:10px;min-height:50px}
.opt .k{width:24px;height:24px;border-radius:7px;background:var(--surface-2);color:var(--ink-faint);font-size:12px;font-weight:800;display:grid;place-items:center;flex:none}
.opt:hover{border-color:var(--brand)}
.opt.sel{border-color:var(--brand);background:var(--brand-soft)}
.opt.ok{border-color:var(--ok);background:var(--ok-soft)}.opt.ok .k{background:var(--ok);color:#fff}
.opt.bad{border-color:var(--bad);background:var(--bad-soft)}.opt.bad .k{background:var(--bad);color:#fff}
.opt:disabled{cursor:default}
.opt svg{max-height:90px;width:auto}
/* ordenar: fichas que se tocan en orden */
.chips{display:flex;flex-wrap:wrap;gap:9px}
.chip{font-size:17px;padding:10px 16px;border:1.5px solid var(--line-strong);border-radius:12px;background:var(--surface);cursor:pointer;transition:.13s;position:relative;font-variant-numeric:tabular-nums}
.chip.picked{border-color:var(--brand);background:var(--brand-soft)}
.chip .ord{position:absolute;top:-8px;right:-8px;width:20px;height:20px;border-radius:50%;background:var(--brand);color:#fff;font-size:11px;font-weight:800;display:grid;place-items:center}
.chip.ok{border-color:var(--ok);background:var(--ok-soft)}.chip.bad{border-color:var(--bad);background:var(--bad-soft)}
.orderline{margin-top:12px;min-height:30px;font-size:16px;color:var(--ink-soft);font-variant-numeric:tabular-nums}
/* relacionar: dos columnas */
.match{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.match .col{display:grid;gap:8px;align-content:start}
.mitem{font-size:15px;padding:11px 12px;border:1.5px solid var(--line-strong);border-radius:12px;background:var(--surface);cursor:pointer;transition:.13s;text-align:left;min-height:46px;display:flex;align-items:center;gap:8px}
.mitem.sel{border-color:var(--brand);background:var(--brand-soft)}
.mitem.paired{border-style:dashed}
.mitem .tag{width:20px;height:20px;border-radius:50%;font-size:11px;font-weight:800;display:grid;place-items:center;color:#fff;flex:none}
.mitem.ok{border-color:var(--ok);background:var(--ok-soft)}.mitem.bad{border-color:var(--bad);background:var(--bad-soft)}
.qrow{display:flex;gap:10px;align-items:center;margin-top:14px;flex-wrap:wrap}
.err{color:var(--bad);font-size:13px;margin-top:8px;display:none}.err.show{display:block}
.fb{border-radius:12px;padding:0;max-height:0;overflow:hidden;transition:.35s;margin-top:0;font-size:15px}
.fb.show{max-height:900px;padding:14px 15px;margin-top:14px}
.fb.good{background:var(--ok-soft)}.fb.bad{background:var(--bad-soft)}
.fb .fbt{font-weight:800;display:block;margin-bottom:6px;font-size:15.5px}
.fb.good .fbt{color:var(--ok)}.fb.bad .fbt{color:var(--bad)}
.fb .why{border-top:1px dashed var(--line-strong);margin-top:8px;padding-top:8px}
.fb .why p{margin:0 0 6px}
.fb .steps{margin:6px 0 0;padding-left:0;list-style:none;counter-reset:s}
.fb .steps li{position:relative;padding-left:26px;margin-bottom:5px;counter-increment:s}
.fb .steps li::before{content:counter(s);position:absolute;left:0;top:2px;width:18px;height:18px;border-radius:50%;background:var(--surface);font-size:11px;font-weight:800;display:grid;place-items:center;color:var(--ink-soft)}
.qnav{display:flex;justify-content:space-between;align-items:center;margin-top:14px;gap:10px}
.finish{text-align:center;padding:26px 18px;background:var(--surface);border:1px solid var(--line);border-radius:20px;margin-top:14px;animation:pop .3s ease}
.finish .big{font-family:var(--font-head);font-size:26px;font-weight:600;margin:0 0 6px}
.finish .scr{font-size:15px;color:var(--ink-soft);margin:0 0 16px}
.finish.win{background:linear-gradient(160deg,var(--brand-soft),var(--surface));border-color:var(--brand)}
.score-ring{width:120px;height:120px;margin:0 auto 10px;position:relative}
.score-ring svg{transform:rotate(-90deg)}
.score-ring .sv{position:absolute;inset:0;display:grid;place-items:center;font-family:var(--font-head);font-size:34px;font-weight:600}
.medal-big{font-size:54px;line-height:1;margin-bottom:6px;animation:bounce .8s ease}
@keyframes bounce{0%{transform:scale(.3)}60%{transform:scale(1.2)}100%{transform:scale(1)}}
.review-list{text-align:left;margin:14px 0 0;display:grid;gap:8px}
.review-item{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border-radius:12px;background:var(--surface-2);font-size:14px}
.review-item .st{flex:none;width:22px;height:22px;border-radius:50%;display:grid;place-items:center;color:#fff;font-size:12px;font-weight:800}
.review-item .st.ok{background:var(--ok)}.review-item .st.bad{background:var(--bad)}
.review-item details{margin-top:4px;font-size:13.5px}
.review-item .bigmath{font-size:1.15em}
.review-item summary{cursor:pointer;color:var(--brand);font-weight:700}
.tag-list{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin:8px 0}
.tag{font-size:13px;padding:5px 11px;border-radius:99px;background:var(--accent-soft);color:var(--accent-ink);font-weight:700}
.tag.good{background:var(--ok-soft);color:var(--ok)}

/* ---------- repaso ---------- */
.plan{display:grid;gap:8px;margin:12px 0}
.plan-item{display:flex;align-items:center;gap:10px;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:10px 12px;font-size:14px}
.plan-item .why{margin-left:auto;font-size:12px;font-weight:800;padding:3px 9px;border-radius:99px;white-space:nowrap}
.why.floja{background:var(--bad-soft);color:var(--bad)}.why.repaso{background:var(--b2s);color:var(--b2)}.why.dominada{background:var(--gold-soft);color:var(--gold)}.why.nueva{background:var(--brand-soft);color:var(--brand-ink)}

/* ---------- progreso ---------- */
.medals{display:grid;grid-template-columns:repeat(auto-fill,minmax(88px,1fr));gap:8px}
.medal-c{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:10px 6px;text-align:center;font-size:11.5px;color:var(--ink-soft);line-height:1.25}
.medal-c .m{font-size:26px;line-height:1.1;display:block;margin-bottom:4px;filter:grayscale(1);opacity:.35}
.medal-c.on .m{filter:none;opacity:1}
.hist{display:grid;gap:6px}
.hist-row{display:flex;align-items:center;gap:10px;padding:9px 12px;background:var(--surface);border:1px solid var(--line);border-radius:10px;font-size:13.5px}
.hist-row .sc{margin-left:auto;font-family:var(--font-head);font-size:18px;font-weight:600;min-width:46px;text-align:right}
.sc.g{color:var(--ok)}.sc.m{color:var(--gold)}.sc.b{color:var(--bad)}

/* ---------- login ---------- */
.login{max-width:400px;margin:40px auto 0}
.login .card{padding:24px}
.field{margin:12px 0}
.field label{display:block;font-size:13px;font-weight:700;color:var(--ink-soft);margin-bottom:5px}
.field input{width:100%;font-size:18px;padding:12px 14px;border:1.5px solid var(--line-strong);border-radius:12px;background:var(--surface);color:var(--ink)}
.field input:focus{outline:none;border-color:var(--brand);box-shadow:0 0 0 4px var(--brand-soft)}
.pin{letter-spacing:.4em;text-align:center;font-family:var(--font-head)}
.toast{position:fixed;left:50%;bottom:24px;transform:translateX(-50%) translateY(20px);background:var(--ink);color:var(--bg);padding:11px 18px;border-radius:12px;font-size:14px;font-weight:600;opacity:0;transition:.3s;z-index:50;max-width:92vw;text-align:center}
.toast.show{opacity:1;transform:translateX(-50%)}
.offline{background:var(--gold-soft);color:var(--accent-ink);font-size:12.5px;text-align:center;padding:6px 10px}

/* confeti */
.confetti{position:fixed;inset:0;pointer-events:none;z-index:40;overflow:hidden}
.confetti i{position:absolute;top:-10px;width:9px;height:14px;border-radius:2px;animation:fall 1.6s ease-in forwards}
@keyframes fall{to{transform:translateY(110vh) rotate(540deg);opacity:.2}}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}
.fade{animation:pop .3s ease}
footer{color:var(--ink-faint);font-size:12.5px;text-align:center;padding:26px 0 10px;border-top:1px solid var(--line);margin-top:30px}

/* =====================================================================
   Tablet y escritorio (secundaria y tablas): aprovechar el ancho sin verse como celular estirado
   ===================================================================== */
@media (min-width:768px){
  .wrap,.topbar .in{max-width:860px}
  body{font-size:16.5px}
  h1{font-size:36px}h2{font-size:27px}
  .lead{font-size:18px}
  .card{padding:22px 24px}
  .topics{grid-template-columns:repeat(3,minmax(0,1fr))}
  .topic{min-height:104px;padding:15px 16px}
  .topic .ttl{font-size:15.5px}.topic .tdesc{font-size:12.8px}
  .stat .v{font-size:30px}.stat .l{font-size:13px}
  .today{padding:26px 28px}
  .qcard{padding:26px 28px}
  .qtext{font-size:21px}
  .opt{font-size:18px;min-height:56px;padding:14px 18px}
  .opts.grid2{grid-template-columns:repeat(4,1fr)}
  .opts.grid2 .opt{justify-content:center}
  .numin{font-size:26px;padding:15px}
  .btn{padding:13px 22px;font-size:16px}
  .btn.sm{font-size:14px;padding:9px 16px}
  .level{padding:18px 12px}.level .lt{font-size:17px}
  .finish{padding:32px 28px}
  .medals{grid-template-columns:repeat(auto-fill,minmax(110px,1fr))}
  .login{max-width:460px;margin-top:56px}
}
@media (min-width:1100px){
  .wrap,.topbar .in{max-width:980px}
  .topics{gap:12px}
  .match{gap:16px}
  .login{max-width:480px}
}
/* dibujos: tamaño natural (width/height del SVG) en pantallas anchas, encogen en celular */
figure.draw svg,.qsvg svg,.fb .why svg,.opt svg,.review-item svg{max-width:100%;height:auto}
@media (min-width:1100px){figure.draw svg,.qsvg svg{zoom:1.15}}
/* barra superior en celular: nada se parte en dos líneas */
.brand span:last-child{white-space:nowrap}
.user-pill{white-space:nowrap;max-width:150px;overflow:hidden;text-overflow:ellipsis}
.streak-pill{white-space:nowrap}
@media (max-width:420px){.brand{font-size:16px}.brand .logo{width:28px;height:28px}.user-pill{max-width:110px;font-size:12.5px}.topbar .in{gap:7px;padding:8px 12px}}
/* tarjetas con botón a la derecha: en celular el botón baja a su propia línea */
@media (max-width:600px){
  .examcard,.bloque-exam,.kfinal{flex-wrap:wrap}
  .examcard .spacer,.bloque-exam .spacer,.kfinal .spacer{flex-basis:100%;height:0}
  .examcard .btn,.bloque-exam .btn,.kfinal .btn{width:100%}
  .examcard>span:last-child:not(.btn),.kfinal .lock{margin-left:auto}
  .scrollx{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:0 -6px;padding:0 6px}
  .scrollx svg{min-width:460px;max-width:none}
}

/* =====================================================================
   Las tablas fáciles (niños 6–8): más grande, más color, menos texto
   ===================================================================== */
body.kids{
  --brand:#2e9e6b; --brand-soft:#dcf5e8; --brand-ink:#17603f;
  --accent:#ff8c42; --accent-soft:#ffe9d9; --accent-ink:#a34f12;
  --gold:#e0a800; --gold-soft:#fff3c4;
  --radius:22px; --font-body:"Fredoka","Figtree","Segoe UI",system-ui,sans-serif; --font-head:"Fredoka","Figtree",system-ui,sans-serif;
  font-size:18px;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) body.kids{--brand:#4fd598;--brand-soft:#173a2e;--brand-ink:#b7f0d6;--accent:#ffa066;--accent-soft:#3b2117;--accent-ink:#ffd0b0;--gold:#ffc93c;--gold-soft:#3a2f10}}
:root[data-theme="dark"] body.kids{--brand:#4fd598;--brand-soft:#173a2e;--brand-ink:#b7f0d6;--accent:#ffa066;--accent-soft:#3b2117;--accent-ink:#ffd0b0;--gold:#ffc93c;--gold-soft:#3a2f10}
body.kids .brand .logo{background:linear-gradient(135deg,#ff5d5d,#ffc93c);font-size:18px}
body.kids h1{font-weight:700;font-size:32px;letter-spacing:0}
body.kids h2{font-weight:700;letter-spacing:0}
body.kids .kicker{color:var(--accent);letter-spacing:.1em}
body.kids .back{font-size:16px}
body.kids .btn{border-radius:16px;font-weight:700}
.kbtn{font-size:18px;padding:14px 24px;border-radius:18px!important;min-height:54px}
.kbtn.accent{background:var(--accent)}
body.kids b.hl{background:var(--gold-soft);color:var(--accent-ink);padding:2px 8px;border-radius:8px}
.bigmath{font-size:1.9em;font-weight:700;letter-spacing:.04em;font-variant-numeric:tabular-nums;display:inline-block;line-height:1.2}
figure.draw.kid{margin:14px 0 6px}
figure.draw.kid figcaption{font-size:14px;color:var(--ink-soft);margin-top:8px;font-weight:600}
@media (min-width:768px){figure.draw.kid svg,body.kids .qsvg svg,body.kids .fb .why svg{zoom:1.2}}
svg.kid{max-width:100%;height:auto}
.kcard{background:var(--surface);border:2px solid var(--line);border-radius:var(--radius);padding:18px;margin:14px 0}
.kcard.idea{border-color:color-mix(in srgb,var(--brand) 45%,transparent);background:linear-gradient(170deg,var(--brand-soft),var(--surface) 40%)}
.kcard.trick{border-color:color-mix(in srgb,var(--accent) 50%,transparent);background:linear-gradient(170deg,var(--accent-soft),var(--surface) 45%)}
.kcard.gold{border-color:color-mix(in srgb,var(--gold) 55%,transparent);background:linear-gradient(170deg,var(--gold-soft),var(--surface) 45%)}
.kcard .kc-h{font-size:14px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;margin:0 0 10px;color:var(--brand-ink)}
.kcard.trick .kc-h{color:var(--accent-ink)}.kcard.gold .kc-h{color:var(--accent-ink)}
.kcard p{margin:0 0 10px;font-size:1.05em;line-height:1.5}.kcard p:last-child{margin-bottom:0}
.kex-steps{margin-top:12px;display:grid;gap:8px}
.kejemplos{display:grid;gap:12px}
.kej{background:var(--surface-2);border-radius:16px;padding:4px 12px 12px}
.kej .kex-steps{margin-top:8px}
@media (min-width:768px){.kejemplos{grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}}
.kstep{display:flex;gap:12px;align-items:center;background:var(--surface);border-radius:14px;padding:10px 14px;border:1px solid var(--line)}
.kstep .n{flex:none;width:30px;height:30px;border-radius:50%;background:var(--accent);color:#fff;font-weight:700;display:grid;place-items:center;font-size:15px}
.ktira-list{display:grid;grid-template-columns:repeat(2,1fr);gap:6px 14px;margin-top:10px;font-variant-numeric:tabular-nums;font-size:1.05em}
.ktira-list span{background:var(--surface-2);border-radius:10px;padding:6px 12px;text-align:center}
.ktira-list b{color:var(--tc,var(--brand))}

/* elegir módulo */
.chooser{max-width:720px}
.choose{display:grid;gap:14px;grid-template-columns:1fr}
.choice{display:flex;flex-direction:column;align-items:center;text-align:center;gap:6px;padding:26px 18px;border-radius:24px;border:2px solid var(--line);background:var(--surface);cursor:pointer;transition:.18s;min-height:150px;justify-content:center}
.choice:hover{transform:translateY(-3px);box-shadow:var(--shadow)}
.choice .ic{width:64px;height:64px;border-radius:18px;display:grid;place-items:center;font-size:30px;color:#fff;margin-bottom:4px}
.choice.secu .ic{background:var(--brand);font-family:var(--font-head)}
.choice.kids .ic{background:linear-gradient(135deg,#ff5d5d,#ffc93c);font-size:34px}
.choice b{font-size:20px}.choice small{color:var(--ink-faint);font-size:13.5px;line-height:1.35}
.choice.secu:hover{border-color:var(--brand)}.choice.kids:hover{border-color:#ff8c42}
@media (min-width:600px){.choose{grid-template-columns:1fr 1fr}}
.kids-login .field input{font-size:22px;padding:14px 16px;border-radius:16px}
.kids-login .btn.big{font-size:20px;min-height:58px}

/* inicio niños */
.khero{display:flex;align-items:center;gap:16px;padding:18px 0 8px}
.khero .sub{font-size:1em}
.kcrown{flex:none;text-align:center;opacity:.55;filter:grayscale(.6)}
.kcrown.on{opacity:1;filter:none;animation:bounce .9s ease}
.kcrown .kc-t{font-size:13px;font-weight:700;color:var(--ink-soft);margin-top:-4px}
.kactions{display:grid;gap:12px;grid-template-columns:1fr;margin:10px 0 18px}
.kbig{display:flex;align-items:center;gap:14px;text-align:left;border:none;border-radius:22px;padding:16px 18px;color:#fff;cursor:pointer;min-height:84px;box-shadow:var(--shadow);transition:.15s}
.kbig:active{transform:scale(.98)}
.kbig:disabled{opacity:.5;cursor:default}
.kbig.today{background:linear-gradient(135deg,#2e9e6b,#27b9a1)}
.kbig.today.done{background:linear-gradient(135deg,#5b6fd6,#8a5cc9)}
.kbig.reto{background:linear-gradient(135deg,#ff8c42,#ff5d5d)}
.kbig .ic{font-size:34px;flex:none}
.kbig b{display:block;font-size:19px;line-height:1.15}
.kbig small{display:block;opacity:.92;font-size:14px;margin-top:3px}
.kbig .kstreak{margin-left:auto;background:rgba(255,255,255,.22);border-radius:99px;padding:6px 12px;font-weight:700;font-size:15px;flex:none}
.ktables{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.ktable{position:relative;display:flex;flex-direction:column;align-items:flex-start;gap:3px;text-align:left;background:var(--surface);border:2.5px solid var(--tc);border-radius:22px;padding:14px 14px 12px;cursor:pointer;transition:.16s;min-height:132px;overflow:hidden;color:var(--ink)}
.ktable::before{content:"";position:absolute;inset:0;background:var(--tc);opacity:.08;pointer-events:none}
.ktable:hover{transform:translateY(-3px);box-shadow:var(--shadow)}
.ktable:active{transform:scale(.98)}
.ktable .knum{width:50px;height:50px;border-radius:16px;background:var(--tc);color:#fff;font-size:28px;font-weight:700;display:grid;place-items:center;line-height:1}
.ktable .ktt{font-weight:700;font-size:17px;margin-top:6px;line-height:1.1}
.ktable .kdesc{font-size:13px;color:var(--ink-faint);line-height:1.25}
.ktable .klv{display:flex;gap:4px;margin-top:auto;padding-top:8px}
.ktable .klv i{width:22px;height:8px;border-radius:99px;background:var(--surface-2);border:1px solid var(--line)}
.ktable .klv i.on{background:var(--tc);border-color:var(--tc)}
.ktable .kmed{position:absolute;top:10px;right:10px;font-size:26px;line-height:1;animation:bounce .8s ease}
.ktable .kex{position:absolute;right:10px;bottom:10px;font-size:11px}
.ktable.medal{box-shadow:0 0 0 3px color-mix(in srgb,var(--tc) 35%,transparent)}
.kstars .off{filter:grayscale(1);opacity:.3}
.kfinal{display:flex;align-items:center;gap:14px;background:var(--surface);border:2px dashed var(--line-strong);border-radius:20px;padding:14px 16px;margin:14px 0}
.kfinal .ic{font-size:32px}
.kfinal b{font-size:17px}.kfinal .d{font-size:14px;color:var(--ink-soft)}
.kfinal.locked{opacity:.7}.kfinal .lock{font-size:24px}
.kh2{margin-top:22px;font-size:24px}

/* una tabla */
.khead{display:flex;align-items:center;gap:16px;padding:8px 0 4px}
.khead h1{margin:0 0 2px;font-size:30px}
.knum.big{flex:none;width:68px;height:68px;border-radius:20px;background:var(--tc);color:#fff;font-size:38px;font-weight:700;display:grid;place-items:center;line-height:1}
.klevels{display:grid;grid-template-columns:1fr;gap:10px;margin:12px 0}
.klevel{display:flex;align-items:center;gap:14px;text-align:left;background:var(--surface);border:2.5px solid var(--line);border-radius:20px;padding:14px 16px;cursor:pointer;transition:.15s;min-height:72px;color:var(--ink)}
.klevel .ic{font-size:30px;flex:none;width:40px;text-align:center}
.klevel .lt{font-weight:700;font-size:19px;display:block}
.klevel .ls{font-size:14px;color:var(--ink-soft);display:block}
.klevel:hover{border-color:var(--tc,var(--brand))}
.klevel.done{border-color:var(--brand);background:var(--brand-soft)}
.klevel.locked{opacity:.55;cursor:not-allowed}
.kback{font-size:16px}

/* ejercicios niños */
body.kids .qcard{border-width:2px;border-radius:24px}
body.kids .qtext{font-size:24px;text-align:center;line-height:1.3}
body.kids .qsub{text-align:center;font-size:16px;color:var(--ink-soft)}
body.kids .qsvg{margin:10px 0 16px}
body.kids .session-top .name{font-size:16px}
body.kids .dots i{height:9px}
.numin.kidin{font-size:40px;font-weight:700;padding:10px;max-width:220px;margin:0 auto 12px;display:block;border-width:3px;border-radius:18px;letter-spacing:.08em;caret-color:transparent}
.kidpad{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;max-width:340px;margin:0 auto}
.kp{font-size:28px;font-weight:700;min-height:62px;border-radius:18px;border:2px solid var(--line-strong);background:var(--surface);cursor:pointer;transition:.1s;font-family:var(--font-head);color:var(--ink)}
.kp:active{transform:scale(.94);background:var(--brand-soft)}
.kp.del{font-size:24px;color:var(--bad)}
.kp.go{background:var(--brand);color:#fff;border-color:var(--brand);font-size:20px}
.opts.big{grid-template-columns:1fr 1fr;gap:12px}
.opts.big .opt{font-size:26px;font-weight:700;justify-content:center;min-height:72px;border-width:2.5px;border-radius:18px;font-family:var(--font-head)}
.opts.big .opt .k{display:none}
body.kids .chip{font-size:22px;padding:12px 20px;min-height:54px}
body.kids .mitem{font-size:20px;min-height:58px;justify-content:center;border-width:2px;border-radius:16px}
body.kids .fb .fbt{font-size:20px}
body.kids .fb.show{padding:16px}
.fb .kstars{font-size:30px;letter-spacing:.1em}
.confetti.stars b{position:absolute;top:30vh;animation:starup 1.4s ease-out forwards}
@keyframes starup{0%{transform:translateY(0) scale(.4);opacity:0}25%{opacity:1}100%{transform:translateY(-40vh) scale(1.2);opacity:0}}
body.kids #nextbtn{font-size:18px;padding:14px 26px;border-radius:18px}
.kfinish .kbigstars{font-size:46px;letter-spacing:.06em;margin-bottom:6px;animation:bounce .8s ease}
.kfinish .big{font-size:30px}
.kfinish .scr{font-size:17px}
.kfinish .medal-big svg{width:84px;height:auto}
.kclock{height:12px;border-radius:99px;background:var(--surface-2);border:1px solid var(--line);overflow:hidden;margin:4px 0 12px}
.kclock i{display:block;height:100%;background:linear-gradient(90deg,#ff5d5d,#ffc93c);transition:width 1s linear}
.kret{font-weight:700;font-size:16px;color:var(--ink)}

/* medallas */
.kcrown-big{display:flex;align-items:center;gap:18px;background:var(--surface);border:2px solid var(--line);border-radius:24px;padding:16px 18px;margin:12px 0}
.kcrown-big.on{border-color:var(--gold);background:linear-gradient(160deg,var(--gold-soft),var(--surface))}
.kcrown-big b{font-size:19px}
.kmedals{display:grid;grid-template-columns:repeat(auto-fill,minmax(96px,1fr));gap:10px;margin:14px 0}
.kmedal{display:flex;flex-direction:column;align-items:center;gap:4px;text-decoration:none;color:var(--ink-soft);font-size:13px;font-weight:600;background:var(--surface);border:2px solid var(--line);border-radius:18px;padding:12px 6px;transition:.15s}
.kmedal:hover{transform:translateY(-2px)}
.kmedal.on{border-color:var(--gold);color:var(--ink)}
.kmedal svg{width:70px;height:auto}
body.kids .hist-row{font-size:15px;border-radius:14px}
body.kids .plan-item{font-size:16px;border-radius:14px}

/* tablet (768+): aprovechar el ancho; botones táctiles grandes */
@media (min-width:768px){
  body.kids{font-size:19px}
  body.kids h1{font-size:38px}
  .ktables{grid-template-columns:repeat(5,minmax(0,1fr));gap:12px}
  .ktable{min-height:150px;padding:14px 12px}
  .ktable .knum{width:52px;height:52px;font-size:30px}
  .ktable .ktt{font-size:16px}
  .kactions{grid-template-columns:1fr 1fr}
  .kbig{min-height:96px}
  .klevels{grid-template-columns:repeat(3,1fr)}
  .klevel{flex-direction:column;text-align:center;padding:18px 12px;min-height:130px;justify-content:center}
  .klevel .ic{font-size:36px}
  .ktira-list{grid-template-columns:repeat(5,1fr)}
  body.kids .qtext{font-size:30px}
  .numin.kidin{font-size:48px;max-width:260px}
  .kidpad{max-width:420px;gap:12px}
  .kp{min-height:72px;font-size:32px}
  .opts.big{grid-template-columns:repeat(4,1fr)}
  .opts.big .opt{font-size:30px;min-height:84px}
  .kmedals{grid-template-columns:repeat(5,1fr)}
  .kfinish .kbigstars{font-size:56px}
}
/* escritorio (1100+) */
@media (min-width:1100px){
  .ktables{gap:14px}
  .ktable{min-height:164px;padding:16px}
  .ktable .knum{width:56px;height:56px;font-size:32px}
  .kcard{padding:22px 26px}
  .kidpad{max-width:440px}
  .kp{min-height:68px}
  .opts.big .opt{min-height:80px}
}
/* celular */
@media (max-width:767px){
  .khero{flex-direction:column;align-items:flex-start}
  .khero .kcrown{align-self:center}
}

/* ---------- Cómo se resuelve, paso a paso (métodos por ficha) ---------- */
.card.metodo{background:linear-gradient(170deg,var(--b2s),var(--surface) 45%);border-color:color-mix(in srgb,var(--b2) 45%,transparent)}
.card.metodo .ct{color:var(--b2)}
.met{border:1px solid var(--line);border-radius:14px;background:var(--surface);margin:0 0 10px;overflow:hidden}
.met:last-child{margin-bottom:0}
.met summary{list-style:none;cursor:pointer;display:flex;align-items:center;gap:10px;padding:12px 14px;font-weight:800;font-size:15.5px}
.met summary::-webkit-details-marker{display:none}
.met summary::after{content:'+';margin-left:auto;font-size:20px;color:var(--b2);font-weight:800;line-height:1}
.met[open] summary::after{content:'−'}
.met[open] summary{border-bottom:1px dashed var(--line)}
.met .mn{flex:none;width:26px;height:26px;border-radius:50%;background:var(--b2);color:#fff;font-size:13px;font-weight:800;display:grid;place-items:center;font-family:var(--font-head)}
.met-body{padding:10px 14px 14px}
.met-body .steps,.ejemplo .steps{margin:4px 0 0;padding-left:0;list-style:none;counter-reset:s}
.met-body .steps li,.ejemplo .steps li{position:relative;padding-left:30px;margin-bottom:8px;counter-increment:s;line-height:1.5}
.met-body .steps li::before,.ejemplo .steps li::before{content:counter(s);position:absolute;left:0;top:2px;width:22px;height:22px;border-radius:50%;background:var(--b2s);color:var(--b2);font-size:12px;font-weight:800;display:grid;place-items:center}
.met-body .steps.big li{font-size:15.5px}
.met-body .ojo{background:var(--gold-soft);border-radius:10px;padding:8px 12px;font-size:14px;margin:8px 0 0}
.met-body .ej-h{font-size:12.5px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;color:var(--ink-soft);margin:14px 0 6px}
.ejemplo{background:var(--surface-2);border-radius:12px;padding:10px 12px;margin:0 0 8px}
.ejemplo:last-child{margin-bottom:0}
.ejemplo .ej-q{font-weight:700;margin-bottom:6px;display:flex;gap:8px;align-items:flex-start;flex-wrap:wrap}
.ejemplo .ej-q .tag{font-size:11.5px;padding:3px 8px;flex:none}
.ejemplo .steps li{font-size:14.5px;margin-bottom:5px}
.ejemplo .steps li::before{background:var(--surface);color:var(--ink-soft)}
.met .fr{font-size:.95em}
@media (min-width:768px){.met-body{padding:12px 18px 16px}.met summary{font-size:16.5px}}