:root{--b:#1b4fb4;--bg:#fcfbf8;--t:#1d2433;--m:#5b6577;--l:#e6e3da;--s:#f5f3ec;--g:#8fd19e;--bl:#8ec5f0;--pk:#f5b5c8;--yl:#f8e37a;--or:#f08a3c;--post:#f9f0a0;--postt:#3b3512;--tree:#16181d;--card:#fff}
@media(prefers-color-scheme:dark){:root{--bg:#14171c;--t:#e6eaf2;--m:#9aa5b8;--l:#2a3140;--s:#1a1f28;--b:#7aa8f0;--tree:#d9d5c8;--card:#1c222c}}
*{box-sizing:border-box}body{margin:0;font:16px/1.6 system-ui,-apple-system,"Segoe UI",Roboto,Arial,sans-serif;background:var(--bg);color:var(--t)}
a{color:var(--b)}
.top{position:sticky;top:0;z-index:20;display:flex;align-items:center;gap:16px;padding:10px 20px;background:var(--b);color:#fff}
.top a{color:#fff;text-decoration:none}.brand{font-weight:700;font-size:1.1rem}.brand span{background:#fff;color:var(--b);border-radius:6px;padding:1px 6px;margin-right:6px}
.topnav{display:flex;gap:14px;margin-left:auto;font-size:.9rem;flex-wrap:wrap}.topnav a{opacity:.9}.topnav a:hover{opacity:1;text-decoration:underline}
.burger{display:none;background:none;border:0;color:#fff;font-size:1.4rem}
.layout{display:grid;grid-template-columns:320px minmax(0,1fr);max-width:1280px;margin:0 auto}.layout.one{grid-template-columns:minmax(0,1fr);max-width:960px}
.side{position:sticky;top:50px;align-self:start;height:calc(100vh - 50px);overflow:auto;padding:16px;border-right:1px solid var(--l);font-size:.86rem;background:var(--s)}
.side input{width:100%;padding:7px 10px;border:1px solid var(--l);border-radius:8px;background:var(--bg);color:var(--t);margin-bottom:10px}
.coursename{font-weight:700;color:var(--b);margin-bottom:6px}
.side summary{cursor:pointer;font-weight:600;padding:3px 0}.side details.nb>summary{color:var(--b);margin-top:6px}.side details.nt{margin-left:8px}.side ul{list-style:none;margin:2px 0 6px 6px;padding:0}
.side li a{display:block;padding:2px 6px;border-radius:6px;text-decoration:none;color:var(--t);line-height:1.35}.side li a:hover{background:var(--l)}.side li a.cur{background:var(--b);color:#fff}
main{padding:24px 32px 60px;min-width:0}
h1{font-size:1.7rem;line-height:1.25;margin:.2em 0 .6em;border-bottom:3px solid var(--b);padding-bottom:.3em}h1 .code{display:inline-block;background:#000;color:#fff;font-size:.8rem;padding:3px 9px;border-radius:5px;margin-right:10px;vertical-align:middle}
h2{color:var(--b);margin-top:1.8em}h3{color:var(--b);margin:1.5em 0 .4em}h4{margin:1em 0 .2em}
.crumb{font-size:.8rem;color:var(--m)}.crumb a{color:var(--m)}
.lead{color:var(--m);font-size:1.05rem}
img{max-width:100%;height:auto}.caption{font-size:.85rem;color:var(--m);text-align:center;font-style:italic}
p img{display:block;margin:10px auto}
math{font-size:1.12em}
blockquote{margin:.2em 0 .6em 1.2em;padding:0;border:0}blockquote p{margin:.2em 0}
.tw{overflow:auto}table{border-collapse:collapse;margin:1em auto}td,th{border:1px solid var(--l);padding:4px 10px}
section.resuelta{background:var(--s);border-left:4px solid var(--b);padding:2px 18px 10px;border-radius:0 10px 10px 0;margin:1.2em 0}section.resuelta h3{margin-top:.8em}
section.recursos{border:1px solid var(--l);border-radius:12px;padding:4px 18px 14px;margin:1.4em 0}
section.problemas{margin-top:2.2em;border-top:3px solid var(--b)}section.problemas h2{margin-top:.6em}
section.problemas>p{margin:.7em 0 .2em}
details.sim{margin:12px 0;border:1px solid var(--l);border-radius:10px;overflow:hidden}details.sim>summary{cursor:pointer;padding:8px 14px;background:var(--s);font-weight:600}
.ggb{width:100%;aspect-ratio:3/2;max-height:640px}.ggb iframe{width:100%;height:100%;border:0;display:block}.ggblink{margin:0;padding:4px 14px 8px;font-size:.8rem;text-align:right}
.pn{display:flex;justify-content:space-between;gap:10px;margin-top:3em;padding-top:1em;border-top:1px solid var(--l);font-size:.9rem}.pn a{text-decoration:none;font-weight:600}
.cards{list-style:none;padding:0;display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:10px}.cards a{display:block;padding:10px 14px;border:1px solid var(--l);border-radius:10px;text-decoration:none;color:var(--t);background:var(--s);height:100%}.cards a:hover{border-color:var(--b)}.cards b{color:var(--b);display:block}.cards i{font-style:normal;float:right}
.home{max-width:960px;margin:0 auto}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin-top:24px}
.tile{display:flex;flex-direction:column;gap:4px;padding:22px;border-radius:14px;background:var(--b);color:#fff;text-decoration:none}.tile b{font-size:1.6rem}.tile i{opacity:.8;font-style:normal;font-size:.85rem}.tile.alt{background:#2f7d5b}
details.nb.u{margin:10px 0;border:1px solid var(--l);border-radius:10px;padding:0 12px}details.nb.u>summary{cursor:pointer;font-weight:700;padding:10px 0;color:var(--b)}
@media(max-width:860px){.layout{grid-template-columns:1fr}.side{display:none;position:static;height:auto}body.nav .side{display:block}.burger{display:block}.topnav{display:none}main{padding:18px 16px 50px}}
@media print{.top,.side,.pn,.ggblink{display:none}.layout{display:block}details.sim{display:none}}
main p{overflow-x:auto;overflow-y:hidden;padding-bottom:2px}
.syl{background:var(--s);border-radius:10px;padding:10px 18px;margin:0 0 1.4em;font-size:.92rem}.syl ul{margin:.3em 0 0;padding-left:1.2em}
.prob{display:flex;gap:10px;margin:14px 0}.prob>div{flex:1;min-width:0}.prob p{margin:.2em 0}.pn1{font-weight:700;color:var(--b);min-width:1.8em}
.b2nav{list-style:none;margin:0;padding:0}.b2nav a{display:block;padding:4px 8px;border-radius:6px;text-decoration:none;color:var(--t)}.b2nav a:hover{background:var(--l)}.b2nav a.cur{background:var(--b);color:#fff}
main ol[type]{margin:.3em 0 .6em;padding-left:1.6em}main ol[type] li{margin:.35em 0}
main blockquote{border-left:3px solid var(--l);padding-left:12px}
main hr{border:0;border-top:1px solid var(--l)}

/* ===== diseño del aula: pared blanca, árbol negro, post-its y números pastel ===== */
.top{background:var(--b);border-bottom:5px solid #0f3a8c}
.brand{display:flex;align-items:center;gap:8px}.brand span{background:none;padding:0;margin:0;font-size:1.15rem;letter-spacing:1px}
.brand span i{font-style:normal;display:inline-block;font-weight:900;font-family:"Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif}
.brand span i:nth-child(1){color:var(--g);transform:rotate(-8deg)}.brand span i:nth-child(2){color:var(--bl)}.brand span i:nth-child(3){color:var(--yl);transform:rotate(7deg)}.brand span i:nth-child(4){color:var(--pk);transform:rotate(-5deg)}.brand span i:nth-child(5){color:var(--or)}.brand span i:nth-child(6){color:var(--g);transform:rotate(6deg)}.brand span i:nth-child(7){color:var(--bl)}
.topnav a.calc{background:var(--post);color:var(--postt);padding:2px 10px;border-radius:4px;transform:rotate(-2deg);font-weight:700;opacity:1}
.numstrip{display:flex;justify-content:center;flex-wrap:wrap;gap:0 2px;overflow:hidden;line-height:1;font-family:"Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif;font-weight:900;user-select:none;pointer-events:none;height:64px}
.numstrip i{font-style:normal;display:inline-block;font-size:44px;opacity:.95}
/* soluciones */
details.sol{margin:8px 0 14px}details.sol>summary{display:inline-block;cursor:pointer;list-style:none;background:var(--post);color:var(--postt);font-weight:700;font-size:.86rem;padding:4px 14px;border-radius:4px;box-shadow:0 1px 3px rgba(0,0,0,.25);transform:rotate(-1deg)}
details.sol>summary::-webkit-details-marker{display:none}details.sol[open]>summary{transform:none;opacity:.75}
.solb{margin-top:8px;background:var(--post);color:var(--postt);border-radius:4px;padding:8px 16px 10px;box-shadow:0 2px 6px rgba(0,0,0,.18)}.solb p{margin:.3em 0}.solb math{font-size:1.1em}
.selfck{margin-top:8px;display:flex;gap:8px;flex-wrap:wrap}.selfck button{font:inherit;font-size:.8rem;padding:2px 10px;border-radius:99px;border:1px solid rgba(0,0,0,.3);background:rgba(255,255,255,.65);color:var(--postt);cursor:pointer}.selfck button.on{background:#2f9e5b;color:#fff;border-color:#2f9e5b}.selfck button[data-v=rep].on{background:var(--or);border-color:var(--or)}
.pq>strong:first-child,.pn1{transition:background .2s}p.pq.ok>strong:first-child,.prob.ok .pn1{background:#2f9e5b;color:#fff;border-radius:99px;padding:0 7px}p.pq.rep>strong:first-child,.prob.rep .pn1{background:var(--or);color:#fff;border-radius:99px;padding:0 7px}
.solbar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:.6em 0 1em;font-size:.88rem;color:var(--m)}.solbar button{font:inherit;font-size:.85rem;padding:4px 14px;border-radius:99px;border:1px solid var(--b);background:var(--bg);color:var(--b);cursor:pointer}.solbar button:hover{background:var(--b);color:#fff}
/* portada */
.hero{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1.15fr);gap:10px;align-items:center;max-width:1180px;margin:0 auto;padding:18px 24px 0}
.hero h1{font-size:2.5rem;border:0;line-height:1.1;margin:.1em 0 .3em}.hero h1 em{font-style:normal;color:var(--b)}
.hero .five{display:inline-block;background:var(--post);color:var(--postt);padding:8px 16px;border-radius:4px;transform:rotate(-2deg);box-shadow:0 3px 8px rgba(0,0,0,.2);font-family:"Segoe Print","Bradley Hand","Comic Sans MS",cursive;font-size:1.05rem;margin-top:8px}
.tree{width:100%}.tree svg{width:100%;height:auto;display:block}
.tree .br{fill:none;stroke:var(--tree);stroke-linecap:round;stroke-linejoin:round}.tree .tr{fill:var(--tree)}
.tree a.note{cursor:pointer;outline:none}.tree a.note g.pn{transition:transform .18s}.tree a.note:hover g.pn,.tree a.note:focus g.pn{transform:translateY(-5px) scale(1.05)}
.tree text{font-family:"Segoe Print","Bradley Hand","Comic Sans MS","Chalkboard SE",cursive}.tree .dg{font-family:"Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif;font-weight:900}
.tree .nt1{font-size:23px;font-weight:700;fill:#2b2710}.tree .nt2{font-size:14px;fill:#4a4420}
.homewrap{max-width:1180px;margin:0 auto;padding:0 24px 60px}.homewrap h2{margin-top:1.2em}
.tile{position:relative;overflow:hidden}.tile::after{content:attr(data-n);position:absolute;right:8px;bottom:-14px;font-size:5.4rem;font-weight:900;opacity:.35;font-family:"Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif;line-height:1;transform:rotate(8deg)}
.tile:nth-child(1){background:var(--b)}.tile:nth-child(1)::after{color:var(--bl)}.tile:nth-child(2){background:#2f7d5b}.tile:nth-child(2)::after{color:var(--g)}.tile.alt{background:#c4571a}.tile.alt::after{color:var(--yl)}
/* juegos */
.gwrap{max-width:760px;margin:0 auto;padding:6px 16px 60px}.gwrap h1{border:0;font-size:1.7rem;margin-bottom:.2em}
.gnav{display:flex;gap:8px;flex-wrap:wrap;margin:10px 0 14px}.gnav a{text-decoration:none;padding:4px 14px;border-radius:4px;background:var(--post);color:var(--postt);font-weight:700;font-size:.9rem;box-shadow:0 1px 3px rgba(0,0,0,.25)}.gnav a:nth-child(odd){transform:rotate(-1.2deg)}.gnav a:nth-child(even){transform:rotate(1deg)}.gnav a.cur{background:var(--b);color:#fff}
.g-head{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap}.g-head button{font:inherit;font-size:.85rem;border:1px solid var(--l);background:var(--card);color:var(--t);padding:5px 12px;cursor:pointer}.g-lv,.g-run{display:flex}.g-lv button:first-child,.g-run button:first-child{border-radius:99px 0 0 99px}.g-lv button:last-child,.g-run button:last-child{border-radius:0 99px 99px 0}.g-head button.on{background:var(--b);color:#fff;border-color:var(--b)}
.g-stats{display:flex;align-items:center;gap:14px;margin:14px 0 10px;font-size:.95rem}.g-bar{flex:1;height:8px;background:var(--l);border-radius:99px;overflow:hidden}.g-bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--g),var(--bl),var(--pk),var(--or));transition:width .3s}.g-tm{font-variant-numeric:tabular-nums;color:var(--m)}
.g-card{background:var(--card);border:2px solid var(--l);border-radius:18px;padding:22px 22px 20px;box-shadow:0 6px 20px rgba(0,0,0,.08);transition:border-color .2s,box-shadow .2s}.g-card.ok{border-color:#2f9e5b;box-shadow:0 0 0 4px rgba(47,158,91,.15)}.g-card.bad{border-color:#d9534f;box-shadow:0 0 0 4px rgba(217,83,79,.13)}
.g-q{font-size:2rem;line-height:1.9;text-align:center;padding:14px 4px;overflow-x:auto;font-family:"Cambria Math","STIX Two Math",Cambria,"Times New Roman",serif}.g-q .op{margin:0 .18em}.g-q sup{font-size:.62em}.g-qm,.eqs{color:var(--m)}
.fr{display:inline-flex;flex-direction:column;vertical-align:middle;text-align:center;line-height:1.15;margin:0 .1em;font-size:.82em}.fr>span:first-child{border-bottom:2px solid currentColor;padding:0 .2em}.fr>span:last-child{padding:0 .2em}
.g-form{display:flex;gap:10px;align-items:center;justify-content:center;flex-wrap:wrap;margin-top:6px}.g-lab{color:var(--m)}.g-form input{font:inherit;font-size:1.4rem;width:min(220px,50vw);padding:8px 14px;border:2px solid var(--l);border-radius:12px;background:var(--bg);color:var(--t);text-align:center}.g-form input:focus{outline:none;border-color:var(--b)}
.g-go,.g-next,.g-alt{font:inherit;font-weight:700;border:0;border-radius:12px;padding:10px 20px;cursor:pointer;background:var(--b);color:#fff}.g-go:disabled{opacity:.4}.g-alt{background:var(--or)}
.g-keys{display:flex;gap:8px;justify-content:center;margin-top:12px;flex-wrap:wrap}.g-keys button{font:inherit;font-size:1.1rem;min-width:44px;padding:6px 10px;border:1px solid var(--l);border-radius:10px;background:var(--s);color:var(--t);cursor:pointer}
.g-fb{text-align:center;min-height:1.6em;margin-top:14px;font-weight:600}.g-fb.good{color:#2f9e5b}.g-fb.no{color:#c0392b}.g-fb.warn{color:#b9770e}
.g-sol{margin-top:6px;font-size:1.05rem}.g-sol summary{cursor:pointer;color:var(--b);font-weight:600}.g-sol ol{list-style:none;padding:0 0 0 4px;margin:.4em 0}.g-sol li{margin:.3em 0}.g-sol sup{font-size:.7em}.g-sol .fr{font-size:.85em}
.g-next{display:none;margin:12px auto 0}
.g-hint{text-align:center;color:var(--m);font-size:.88rem}
.g-end{text-align:center;padding:10px}.g-stars{font-size:3rem;color:var(--yl);text-shadow:0 1px 0 #c9a400}.g-stars span{color:var(--l);text-shadow:none}.g-endb{display:flex;gap:10px;justify-content:center;margin-top:14px}
.gintro{color:var(--m);margin:.2em 0 .6em}
@media(max-width:860px){.hero{grid-template-columns:1fr;padding:12px 14px 0}.hero h1{font-size:1.9rem}.g-q{font-size:1.5rem}.numstrip{height:48px}.numstrip i{font-size:34px}}
@media print{.numstrip,.tree,.solbar{display:none}details.sol{display:block}details.sol .solb{display:block}}

.reloj{display:grid;grid-template-columns:minmax(0,380px) minmax(0,1fr);gap:28px;align-items:center;max-width:1000px;margin:10px auto 10px;padding:10px 24px}
.ck-dial svg{width:100%;height:auto;display:block;filter:drop-shadow(0 6px 10px rgba(0,0,0,.15))}#ck-hand{transition:transform 1s}
.ck-t{font:700 15px "Segoe Print","Bradley Hand","Comic Sans MS",cursive;fill:var(--t)}.ck-s{font:900 17px "Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif;fill:#222}.ck-s.ck-b{font-size:12px;fill:var(--m)}
.ck-time{font:900 3.4rem/1 "Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif;margin:.1em 0;color:var(--b)}.ck-state{font-size:1.15rem;background:var(--post);color:var(--postt);display:inline-block;padding:8px 14px;border-radius:4px;box-shadow:0 3px 8px rgba(0,0,0,.2);transform:rotate(-1deg)}.ck-note{color:var(--m);font-size:.88rem}.ck-info h2{margin:0}
@media(max-width:760px){.reloj{grid-template-columns:1fr}.ck-dial{max-width:340px;margin:0 auto}}

.reloj{grid-template-columns:minmax(0,540px) minmax(0,1fr);max-width:1100px}
.ck-t{font:600 9px "Segoe Print","Bradley Hand",cursive;fill:#8a8a8a}.ck-n{font:700 64px "Segoe Print","Bradley Hand","Comic Sans MS",cursive;fill:#16181d}.ck-d text{font-family:"Segoe Print","Bradley Hand",cursive;fill:#16181d;opacity:.85}

.ck-t{font:700 14px "Segoe Print","Bradley Hand",cursive;fill:var(--t)}
.ck-t{font:700 14px "Segoe Print","Bradley Hand",cursive;fill:var(--t)}
.schoolf{text-align:center;padding:34px 16px 40px;border-top:1px solid var(--l);margin-top:30px}.schoolf img{max-width:220px;height:auto;background:#fff;border-radius:10px;padding:8px 14px;transition:transform .2s}.schoolf a:hover img{transform:scale(1.04)}@media print{.schoolf{display:none}}
.ck-dial svg{overflow:visible}
.hero h1 em{font-size:.78em}.abtn{display:inline-block;background:var(--b);color:#fff;text-decoration:none;font-weight:700;padding:10px 22px;border-radius:6px}.abtn.off{background:var(--m);opacity:.7}
.ck-nn{font:900 34px "Arial Rounded MT Bold","Nunito","Trebuchet MS",system-ui,sans-serif}#ck-ss{transition:none}
.ggbc{height:100%;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;padding:16px;background:var(--s);gap:2px;font-size:.92rem}.ggbc p{margin:.3em 0}.ggbc .sm{font-size:.8rem}.ggbc button.abtn{border:0;cursor:pointer;font:inherit;font-weight:700;background:var(--b);color:#fff;padding:8px 20px;border-radius:6px}.ggbc label{font-size:.85rem;color:var(--m)}
.legalf{display:flex;gap:18px;justify-content:center;flex-wrap:wrap;font-size:.8rem;margin-top:16px}.legalf a{color:var(--m)}
.legal{max-width:760px;margin:0 auto;padding:10px 20px 40px}.legal h1{font-size:1.7rem}.legal h2{font-size:1.2rem}.legal button{font:inherit;padding:6px 16px;border-radius:6px;border:1px solid var(--b);background:var(--bg);color:var(--b);cursor:pointer}
.cbanner{position:fixed;left:12px;right:12px;bottom:12px;z-index:50;max-width:860px;margin:0 auto;background:var(--card);color:var(--t);border:1px solid var(--l);border-radius:12px;box-shadow:0 8px 30px rgba(0,0,0,.25);padding:14px 18px;display:flex;gap:16px;align-items:center;flex-wrap:wrap;font-size:.9rem}.cbanner p{margin:0;flex:1 1 380px}.cbanner button.abtn{border:0;cursor:pointer;font:inherit;font-weight:700;background:var(--b);color:#fff;padding:8px 18px;border-radius:6px}.cbanner button.alt{background:var(--m)}
.ck-n{font:600 44px "Didot","Bodoni 72","Playfair Display","Hoefler Text",Georgia,"Times New Roman",serif;fill:#16181d;letter-spacing:0}
.sform{display:flex;gap:8px;margin:10px 0}.sform input{flex:1;font:inherit;font-size:1.05rem;padding:10px 14px;border:2px solid var(--l);border-radius:10px;background:var(--card);color:var(--t)}.sform input:focus{outline:none;border-color:var(--b)}.sform .abtn{border:0;cursor:pointer;font:inherit}
.results{list-style:none;padding:0}.results li{padding:12px 0;border-bottom:1px solid var(--l)}.results a{text-decoration:none;font-size:1.05rem}.results p{margin:.3em 0 0;color:var(--m);font-size:.9rem}.results mark{background:var(--yl);color:#000;border-radius:2px;padding:0 1px}.rc{font-size:.75rem;background:var(--s);border:1px solid var(--l);border-radius:99px;padding:1px 8px;color:var(--m);margin-left:6px}
.abtn.alt{background:var(--m)}label.abtn{cursor:pointer}.prog{max-width:820px}.pbig{display:flex;gap:12px;flex-wrap:wrap;margin:14px 0}.pbig div{flex:1 1 150px;background:var(--post);color:var(--postt);padding:14px 18px;border-radius:4px;box-shadow:0 2px 6px rgba(0,0,0,.2)}.pbig b{display:block;font-size:2.2rem;line-height:1}.pbig span{font-size:.85rem}
.pbar{height:12px;background:var(--l);border-radius:99px;overflow:hidden;display:flex}.pbar i{background:#2f9e5b}.pbar b{background:var(--or)}.ptab{width:100%;border-collapse:collapse;font-size:.9rem}.ptab td,.ptab th{border-bottom:1px solid var(--l);padding:6px 8px;text-align:left;border-left:0;border-right:0}.pr{color:var(--or);font-weight:600}.rl{columns:2;font-size:.9rem}@media(max-width:700px){.rl{columns:1}}
label.abtn{font:inherit;font-weight:700;padding:10px 22px;display:inline-block;font-size:1rem}.prog .abtn{font-size:.95rem}
.fcw{max-width:820px}.fc-top{margin:8px 0}.fc-groups{margin:8px 0}.fc-g{border:1px solid var(--l);border-radius:10px;margin:8px 0;padding:6px 14px;background:var(--card)}.fc-g summary{cursor:pointer;padding:4px 0}.fc-g ul{list-style:none;padding-left:22px;margin:4px 0 8px}.fc-g li{padding:2px 0;font-size:.92rem}.fc-opt{display:flex;gap:18px;flex-wrap:wrap;margin:14px 0;align-items:center}.fc-opt select{font:inherit;padding:4px 8px;border-radius:6px;border:1px solid var(--l);background:var(--card);color:var(--t)}
.abtn.sm{padding:4px 12px;font-size:.8rem}.fcw .abtn{border:0;cursor:pointer;font:inherit;font-weight:700;color:#fff;background:var(--b);padding:9px 20px;border-radius:6px}.fcw .abtn.alt{background:var(--m)}.fcw .abtn.yes{background:#2f9e5b}.fcw .abtn.no{background:var(--or)}
.fc-bar{display:flex;align-items:center;gap:14px;margin:10px 0}.fc-scene{perspective:1200px;margin:8px 0}.fc-card{position:relative;min-height:300px;transform-style:preserve-3d;transition:transform .55s;cursor:pointer;outline:none}.fc-card.on{transform:rotateY(180deg)}
.fc-face{position:absolute;inset:0;backface-visibility:hidden;-webkit-backface-visibility:hidden;border-radius:16px;padding:20px 24px;display:flex;flex-direction:column;justify-content:center;align-items:center;text-align:center;box-shadow:0 6px 20px rgba(0,0,0,.14);overflow:auto}
.fc-front{background:var(--card);border:2px solid var(--l)}.fc-back{background:var(--post);color:var(--postt);transform:rotateY(180deg)}.fc-q{font-size:1.25rem;line-height:1.7}.fc-q math{font-size:1.15em}.fc-tag{position:absolute;top:10px;left:16px;right:16px;font-size:.72rem;color:var(--m);text-align:left}.fc-back .fc-tag{color:var(--postt);opacity:.7}.fc-hint{position:absolute;bottom:10px;font-size:.75rem;color:var(--m)}
.fc-btns{display:flex;gap:14px;justify-content:center;margin:16px 0}.fc-keys{text-align:center;font-size:.8rem;color:var(--m)}
@media(max-width:700px){.fc-card{min-height:340px}.fc-q{font-size:1.1rem}}
.fct{min-height:110px}