*{box-sizing:border-box}
body{
  margin:0;
  min-height:100vh;
  font-family:system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",Arial,sans-serif;
  background:
    radial-gradient(circle at 0% 0%, rgba(249,115,22,.48), transparent 42%),
    radial-gradient(circle at 100% 20%, rgba(245,158,11,.38), transparent 40%),
    #0f172a;
  color:#f8fafc;
  display:flex;
  justify-content:center;
  align-items:center;
  padding:20px;
}
.shell{width:100%;max-width:900px}
.card{
  background:rgba(15,23,42,.9);
  border:1px solid rgba(148,163,184,.35);
  border-radius:24px;
  padding:24px;
  box-shadow:0 24px 70px rgba(0,0,0,.45);
}
.hidden{display:none!important}
.eyebrow,.progress-label,.hint,.lead,.teacher-note small{color:#cbd5e1}
h1{margin:6px 0 8px;text-align:center;font-size:2rem}
.lead{text-align:center;margin:0 auto 20px;max-width:680px;line-height:1.5}
.mode-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin:18px 0}
.mode-card{
  text-align:left;
  min-height:150px;
  border:1px solid rgba(148,163,184,.35);
  background:linear-gradient(145deg,rgba(30,41,59,.95),rgba(15,23,42,.95));
  color:#f8fafc;
  border-radius:20px;
  padding:16px;
  cursor:pointer;
  transition:.15s ease;
}
.mode-card:hover{transform:translateY(-2px);border-color:#fb923c;box-shadow:0 16px 34px rgba(249,115,22,.18)}
.mode-icon{display:block;font-size:2rem;margin-bottom:8px}
.mode-card strong{display:block;font-size:1.02rem;margin-bottom:5px}
.mode-card small{display:block;color:#cbd5e1;line-height:1.35}
.teacher-note{margin-top:12px;padding:12px;border-radius:16px;background:rgba(251,146,60,.12);border:1px solid rgba(251,146,60,.25)}
.topbar{display:flex;justify-content:space-between;gap:12px;align-items:center;margin-bottom:14px}
.pill{border:1px solid rgba(148,163,184,.45);background:rgba(30,41,59,.75);border-radius:999px;padding:8px 12px;color:#fed7aa;font-weight:800}
.progress-wrap{margin-bottom:16px}.progress-bg{height:10px;border-radius:999px;background:#020617;overflow:hidden;border:1px solid rgba(148,163,184,.35)}
.progress-fill{height:100%;width:0;background:linear-gradient(90deg,#fb923c,#f97316,#f59e0b);transition:width .2s ease}.progress-label{text-align:right;margin-top:5px;font-size:.85rem}
.question-text h2{margin:8px 0 4px;font-size:1.35rem}.hint{margin:0 0 12px}
.q-image{margin:12px 0 16px;border-radius:18px;overflow:hidden;border:1px solid rgba(148,163,184,.35);background:#020617}.q-image img{display:block;width:100%;max-height:320px;object-fit:cover}.q-credit{padding:8px 10px;color:#94a3b8;font-size:.78rem}.q-credit a{color:#fdba74}
.options{display:grid;gap:10px}.option{
  width:100%;text-align:left;border:1px solid rgba(148,163,184,.45);background:#1e293b;color:#f8fafc;border-radius:16px;padding:13px;cursor:pointer;font-size:1rem;transition:.12s ease
}.option:hover{background:#334155;border-color:#fb923c}.option.selected{background:#fb923c;color:#0f172a;font-weight:900;border-color:#fdba74}
.short-answer{width:100%;padding:13px;border-radius:16px;border:1px solid rgba(148,163,184,.5);background:#020617;color:#f8fafc;font-size:1rem}.short-answer:focus{outline:2px solid #fb923c}
.nav-row{display:flex;justify-content:space-between;gap:10px;margin-top:18px}.btn{border:none;border-radius:999px;padding:10px 17px;cursor:pointer;font-weight:900}.btn.primary{background:linear-gradient(135deg,#fb923c,#f97316);color:#0f172a}.btn.ghost{background:transparent;color:#f8fafc;border:1px solid rgba(148,163,184,.55)}.btn:disabled{opacity:.4;cursor:not-allowed}.btn:hover:not(:disabled){transform:translateY(-1px)}
.score{font-size:1.6rem;color:#fdba74;font-weight:900;margin:8px 0}.result-actions{display:flex;gap:10px;flex-wrap:wrap;margin:14px 0}.fallo{background:#1e293b;border:1px solid rgba(148,163,184,.25);padding:13px;margin:10px 0;border-radius:16px}.perfect{font-size:1.1rem;color:#bbf7d0;font-weight:900}
@media(max-width:720px){.mode-grid{grid-template-columns:1fr}.nav-row{flex-direction:column-reverse}.btn{width:100%}.topbar{flex-direction:column;align-items:stretch}.progress-label{text-align:left}}