:root{
  --bg:#f4f2ff;
  --card:#ffffff;
  --primary:#7c4dff;
  --primary-dark:#5e35b1;
  --text:#2a2a3a;
  --muted:#7a7a8c;
  --ok:#2e7d32;
  --err:#c62828;
  --radius:16px;
  --shadow:0 2px 12px rgba(124,77,255,.10);
}
*{box-sizing:border-box;margin:0;padding:0;-webkit-tap-highlight-color:transparent}
html,body{height:100%}
body{
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  background:var(--bg);color:var(--text);line-height:1.5;
  padding-bottom:env(safe-area-inset-bottom);
}
/* Topbar */
.topbar{
  position:sticky;top:0;z-index:20;
  background:linear-gradient(135deg,var(--primary),var(--primary-dark));
  color:#fff;padding:14px 16px;
  display:flex;justify-content:space-between;align-items:center;
  box-shadow:0 2px 10px rgba(0,0,0,.15);
}
.brand{display:flex;align-items:center;gap:10px}
.logo{font-size:1.6rem}
.brand h1{font-size:1.2rem;font-weight:700}
.tagline{font-size:.72rem;opacity:.9;font-style:italic}
.streak{background:rgba(255,255,255,.2);padding:6px 12px;border-radius:20px;font-weight:700;font-size:.9rem}
/* Tabs */
.tabs{
  position:sticky;top:60px;z-index:15;
  display:flex;overflow-x:auto;background:#fff;
  border-bottom:1px solid #eee;box-shadow:0 1px 4px rgba(0,0,0,.05);
}
.tab{
  flex:1;min-width:88px;padding:12px 6px;border:none;background:none;
  font-size:.82rem;font-weight:600;color:var(--muted);cursor:pointer;
  border-bottom:3px solid transparent;white-space:nowrap;
}
.tab.active{color:var(--primary);border-bottom-color:var(--primary)}
/* Main */
main{padding:16px;max-width:640px;margin:0 auto}
.view{display:none}
.view.active{display:block}
.view-title{font-size:1.3rem;margin-bottom:12px}
/* Cards */
.card{
  background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
  padding:18px;margin-bottom:14px;
}
.card h2{font-size:1.2rem;margin-bottom:6px}
.card h3{font-size:1rem;margin-bottom:8px}
.card p{margin-bottom:8px}
.muted{color:var(--muted);font-size:.85rem}
.hero{background:linear-gradient(135deg,#fff,#f0eaff)}
/* Stats */
.stats{display:flex;justify-content:space-around;text-align:center}
.stat{display:flex;flex-direction:column}
.stat-num{font-size:1.6rem;font-weight:800;color:var(--primary)}
.stat-label{font-size:.75rem;color:var(--muted)}
/* Buttons */
.btn{
  display:inline-block;background:var(--primary);color:#fff;border:none;
  padding:12px 18px;border-radius:12px;font-size:.95rem;font-weight:600;
  cursor:pointer;text-decoration:none;text-align:center;width:100%;
}
.btn.ghost{background:#eee;color:var(--text)}
.btn:disabled{opacity:.5;cursor:not-allowed}
/* Lists */
.lista{display:flex;flex-direction:column;gap:10px}
.item{
  background:var(--card);border-radius:12px;box-shadow:var(--shadow);
  padding:14px;cursor:pointer;border-left:4px solid var(--primary);
}
.item h4{font-size:.98rem;margin-bottom:2px}
.item p{font-size:.82rem;color:var(--muted);margin:0}
/* Test */
.pregunta{font-size:1.05rem;font-weight:600;margin:12px 0}
.opciones{display:flex;flex-direction:column;gap:10px;margin-bottom:14px}
.opcion{
  background:#f6f4ff;border:2px solid #e4defa;border-radius:12px;
  padding:14px;font-size:.95rem;cursor:pointer;text-align:left;
}
.opcion.selected{border-color:var(--primary);background:#ece4ff}
.opcion.correct{border-color:var(--ok);background:#e8f5e9}
.opcion.wrong{border-color:var(--err);background:#ffebee}
.feedback{border-radius:12px;padding:12px;margin-bottom:12px;font-size:.9rem}
.feedback.ok{background:#e8f5e9;color:var(--ok)}
.feedback.ko{background:#ffebee;color:var(--err)}
.test-nav{display:flex;gap:10px}
.test-nav .btn{flex:1}
.hidden{display:none!important}
/* Input */
.input{
  width:100%;padding:12px;border:2px solid #e4defa;border-radius:12px;
  font-size:1rem;background:#fff;
}
/* Footer */
.footer{text-align:center;color:var(--muted);font-size:.75rem;padding:20px 16px 30px}