:root{
  --paper:#FAFAF6;
  --grid:#CFE1F0;
  --margin:#D8544A;
  --ink:#26323E;
  --ink-soft:#5A6B7B;
  --highlight:#FFC857;

  --numeros:#2F6F8F;
  --numeros-bg:#E7F1F6;
  --geometria:#3F8C5F;
  --geometria-bg:#E9F5EE;
  --algebra:#7B5EA7;
  --algebra-bg:#F1ECF7;
  --dados:#D97A34;
  --dados-bg:#FBEEE1;

  --card-shadow: 0 1px 0 rgba(38,50,62,.06), 0 12px 28px -14px rgba(38,50,62,.35);
  --radius-lg: 18px;
  --radius-md: 12px;

  --font-display:'Caveat', cursive;
  --font-body:'Outfit', system-ui, -apple-system, sans-serif;
  --font-mono:'IBM Plex Mono', ui-monospace, monospace;
}

*{box-sizing:border-box;}
html,body{height:100%;}
body{
  margin:0;
  min-height:100vh;
  font-family:var(--font-body);
  color:var(--ink);
  background:
    linear-gradient(90deg, transparent 0 39px, var(--grid) 39px 40px, transparent 40px) ,
    repeating-linear-gradient(0deg, transparent 0 27px, var(--grid) 27px 28px),
    repeating-linear-gradient(90deg, transparent 0 27px, var(--grid) 27px 28px),
    var(--paper);
  background-size: 100% 100%, 100% 28px, 28px 100%, 100% 100%;
  padding-left: 44px;
  position:relative;
  overflow-x:hidden;
}
@media (prefers-reduced-motion: reduce){
  *{animation-duration:.001ms !important; transition-duration:.001ms !important;}
}

.margin-line{
  position:fixed;
  left:40px; top:0; bottom:0;
  width:2px;
  background:var(--margin);
  opacity:.55;
  z-index:0;
}

.topbar{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:12px;
  padding:20px 18px 8px;
  position:relative;
  z-index:1;
}
.brand{display:flex; align-items:center; gap:12px;}
.brand-mark{
  font-family:var(--font-mono);
  font-weight:600;
  font-size:.78rem;
  letter-spacing:.06em;
  color:var(--paper);
  background:var(--ink);
  padding:6px 9px;
  border-radius:8px;
  transform:rotate(-3deg);
}
.brand-text h1{
  margin:0;
  font-family:var(--font-body);
  font-weight:800;
  font-size:1.32rem;
  line-height:1;
  letter-spacing:-.01em;
}
.brand-text h1 .hand{
  font-family:var(--font-display);
  font-weight:700;
  color:var(--numeros);
  font-size:1.5em;
  margin-left:4px;
}
.subtitle{
  margin:4px 0 0;
  font-size:.78rem;
  color:var(--ink-soft);
  font-family:var(--font-mono);
}
.install-btn{
  border:1.5px solid var(--ink);
  background:var(--paper);
  color:var(--ink);
  font-family:var(--font-body);
  font-weight:600;
  font-size:.82rem;
  padding:8px 14px;
  border-radius:100px;
  cursor:pointer;
}

.stage--picker{padding-top:14px;}
.picker-intro{
  font-family:var(--font-display);
  font-weight:700;
  font-size:1.5rem;
  color:var(--ink);
  margin:0 0 18px;
}
.tile-grid{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:12px;
  width:100%;
}
.tile{
  all:unset;
  box-sizing:border-box;
  display:flex;
  flex-direction:column;
  align-items:flex-start;
  gap:6px;
  cursor:pointer;
  background:#fff;
  border:1.5px solid rgba(38,50,62,.14);
  border-radius:var(--radius-md);
  box-shadow:var(--card-shadow);
  padding:18px 16px;
  min-height:76px;
  transition:transform .12s ease, border-color .12s ease;
}
.tile:active{transform:scale(.97);}
.tile-label{
  font-family:var(--font-body);
  font-weight:700;
  font-size:1rem;
  color:var(--ink);
}
.tile--locked{
  cursor:default;
  background:rgba(38,50,62,.04);
  box-shadow:none;
}
.tile--locked .tile-label{color:var(--ink-soft);}
.tile-badge{
  font-family:var(--font-mono);
  font-size:.68rem;
  text-transform:uppercase;
  letter-spacing:.04em;
  color:var(--ink-soft);
  background:rgba(38,50,62,.08);
  padding:3px 8px;
  border-radius:100px;
}

.back-link{
  display:inline-block;
  background:none;
  border:none;
  font-family:var(--font-mono);
  font-size:.76rem;
  color:var(--ink-soft);
  text-decoration:underline;
  cursor:pointer;
  padding:0 0 12px;
}
.back-link--floating{
  padding-left:18px;
  padding-top:10px;
}

.tabs{
  display:flex;
  gap:8px;
  overflow-x:auto;
  padding:10px 18px 14px;
  position:relative;
  z-index:1;
  scrollbar-width:none;
}
.tabs::-webkit-scrollbar{display:none;}
.tab{
  flex:0 0 auto;
  font-family:var(--font-body);
  font-weight:600;
  font-size:.82rem;
  color:var(--ink-soft);
  background:#fff;
  border:1.5px solid rgba(38,50,62,.12);
  padding:8px 14px;
  border-radius:100px;
  cursor:pointer;
  display:flex;
  align-items:center;
  gap:6px;
  white-space:nowrap;
  transition:transform .12s ease, border-color .12s ease, color .12s ease, background .12s ease;
}
.tab:active{transform:scale(.96);}
.tab-count{
  font-family:var(--font-mono);
  font-size:.7rem;
  opacity:.7;
}
.tab.is-active{color:#fff; border-color:transparent;}
.tab--all.is-active{background:var(--ink);}
.tab--numeros.is-active{background:var(--numeros);}
.tab--geometria.is-active{background:var(--geometria);}
.tab--algebra.is-active{background:var(--algebra);}
.tab--dados.is-active{background:var(--dados);}

.stage{
  position:relative;
  z-index:1;
  max-width:520px;
  margin:0 auto;
  padding:6px 18px 10px;
  display:flex;
  flex-direction:column;
  align-items:center;
}

.deck-meta{
  width:100%;
  display:flex;
  align-items:center;
  gap:8px;
  font-family:var(--font-mono);
  font-size:.76rem;
  color:var(--ink-soft);
  padding:2px 6px 10px;
}
.deck-meta .dot{opacity:.5;}
#deck-topic{
  overflow:hidden;
  text-overflow:ellipsis;
  white-space:nowrap;
}

.card-wrap{
  width:100%;
  perspective:1600px;
  margin-bottom:16px;
}
.card{
  all:unset;
  display:block;
  position:relative;
  width:100%;
  min-height:340px;
  cursor:pointer;
  transform-style:preserve-3d;
  transition:transform .5s cubic-bezier(.2,.7,.3,1);
}
.card.is-flipped{transform:rotateY(180deg);}
.card-face{
  position:absolute;
  inset:0;
  backface-visibility:hidden;
  border-radius:var(--radius-lg);
  background:#fff;
  border:1.5px solid rgba(38,50,62,.14);
  box-shadow:var(--card-shadow);
  padding:26px 22px;
  display:flex;
  flex-direction:column;
}
.card-front{
  justify-content:flex-start;
}
.card-back{
  transform:rotateY(180deg);
  justify-content:flex-start;
  background:#fff;
}
.card::before{
  content:"";
  position:absolute;
  top:14px; right:14px;
  width:34px; height:16px;
  background:var(--domain-color, var(--numeros));
  clip-path:polygon(0 0, 100% 0, 85% 100%, 15% 100%);
  opacity:.9;
  z-index:2;
}

.tag{
  align-self:flex-start;
  font-family:var(--font-mono);
  font-weight:600;
  font-size:.72rem;
  letter-spacing:.03em;
  text-transform:uppercase;
  color:var(--domain-color, var(--numeros));
  background:var(--domain-bg, var(--numeros-bg));
  padding:5px 10px;
  border-radius:7px;
  margin-bottom:16px;
}
.tag--answer{color:#fff; background:var(--domain-color, var(--numeros));}

.question{
  font-family:var(--font-body);
  font-weight:600;
  font-size:1.28rem;
  line-height:1.4;
  margin:0 0 auto;
  color:var(--ink);
}
.answer{
  font-family:var(--font-display);
  font-weight:700;
  font-size:1.9rem;
  line-height:1.15;
  margin:0 0 12px;
  color:var(--domain-color, var(--numeros));
}
.explanation{
  font-family:var(--font-body);
  font-size:.95rem;
  line-height:1.5;
  color:var(--ink-soft);
  margin:0;
}
.flip-hint{
  margin-top:16px;
  font-family:var(--font-mono);
  font-size:.7rem;
  color:var(--ink-soft);
  opacity:.65;
  align-self:center;
}

.rate-row{
  display:flex;
  gap:10px;
  width:100%;
  margin-bottom:14px;
}
.rate-btn{
  flex:1;
  font-family:var(--font-body);
  font-weight:700;
  font-size:.92rem;
  padding:13px 10px;
  border-radius:var(--radius-md);
  border:1.5px solid transparent;
  cursor:pointer;
  transition:transform .1s ease;
}
.rate-btn:active{transform:scale(.97);}
.rate-btn--no{background:#fff; border-color:rgba(216,84,74,.4); color:var(--margin);}
.rate-btn--yes{background:var(--geometria); color:#fff;}

.controls{
  display:flex;
  align-items:center;
  gap:10px;
  width:100%;
}
.btn{
  font-family:var(--font-body);
  font-weight:600;
  font-size:.92rem;
  border-radius:100px;
  padding:12px 16px;
  cursor:pointer;
  border:none;
}
.btn--primary{
  flex:1;
  background:var(--ink);
  color:var(--paper);
}
.btn--ghost{
  background:#fff;
  border:1.5px solid rgba(38,50,62,.16);
  color:var(--ink);
}
.btn:active{transform:scale(.97);}

.statsbar{
  position:relative;
  z-index:1;
  max-width:520px;
  margin:8px auto 26px;
  padding:14px 18px 0;
  display:flex;
  align-items:center;
  gap:22px;
  flex-wrap:wrap;
}
.stat{display:flex; flex-direction:column; align-items:flex-start;}
.stat-num{
  font-family:var(--font-mono);
  font-weight:600;
  font-size:1.1rem;
  color:var(--ink);
}
.stat-label{
  font-size:.68rem;
  color:var(--ink-soft);
  text-transform:uppercase;
  letter-spacing:.04em;
}
.reset-link{
  margin-left:auto;
  background:none;
  border:none;
  font-family:var(--font-mono);
  font-size:.7rem;
  color:var(--ink-soft);
  text-decoration:underline;
  cursor:pointer;
  padding:4px 0;
}

.toast{
  position:fixed;
  left:50%;
  bottom:24px;
  transform:translateX(-50%);
  background:var(--ink);
  color:var(--paper);
  font-family:var(--font-body);
  font-weight:600;
  font-size:.85rem;
  padding:10px 18px;
  border-radius:100px;
  z-index:20;
  box-shadow:0 10px 24px -8px rgba(0,0,0,.4);
}

@media (max-width:380px){
  .brand-text h1{font-size:1.15rem;}
  .answer{font-size:1.6rem;}
  .card{min-height:310px;}
}