:root{--bg:#f4f5f7;--card:#fff;--text:#1d2330;--muted:#6b7280;--line:#e2e5ea;--accent:#0f62fe;--ok:#0a7d3b;--err:#c62828}@media (prefers-color-scheme:dark){:root{--bg:#14171c;--card:#1d2128;--text:#e8eaee;--muted:#9aa2ad;--line:#2e343d;--accent:#5b9bff;--ok:#4cc27c;--err:#ff6b6b}}*{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0;font:16px/1.4 system-ui,-apple-system,Segoe UI,Roboto,sans-serif}main{max-width:640px;margin:0 auto;padding:24px 16px 48px}.cabecera{justify-content:space-between;align-items:center;gap:12px;margin-bottom:16px;display:flex}h1{margin:0;font-size:22px}.card{background:var(--card);border:1px solid var(--line);border-radius:12px;margin-bottom:16px;padding:20px}.fields{grid-template-columns:1fr 140px;gap:12px;display:grid}label{color:var(--muted);margin-bottom:6px;font-size:13px;display:block}input{border:2px solid var(--line);background:var(--bg);width:100%;color:var(--text);border-radius:8px;padding:10px 12px;font-size:26px}input:focus{border-color:var(--accent);outline:none}#letras{text-transform:uppercase;text-align:center;letter-spacing:2px}.result{margin-top:20px}.neto{color:var(--ok);font-variant-numeric:tabular-nums;font-size:40px;font-weight:700}.detalle{color:var(--muted);font-variant-numeric:tabular-nums;margin-top:4px;font-size:14px}.error{color:var(--err);font-weight:600}.actions{flex-wrap:wrap;gap:8px;margin-top:14px;display:flex}button{font:inherit;border:1px solid var(--line);background:var(--bg);color:var(--text);cursor:pointer;border-radius:8px;padding:8px 14px;font-size:14px}.tabla-letras{grid-template-columns:repeat(auto-fill,minmax(70px,1fr));gap:6px;display:grid}.tabla-letras div{border:1px solid var(--line);text-align:center;border-radius:6px;padding:6px;font-size:14px}.tabla-letras b{margin-right:4px}h2{margin:0 0 12px;font-size:15px}.vacio{color:var(--muted);font-size:14px}.aviso{text-align:center;align-content:center;place-items:center;gap:12px;min-height:100svh;display:grid}.aviso h1{font-size:20px}.aviso p{max-width:34rem;margin:0;line-height:1.6}@media (max-width:420px){.fields{grid-template-columns:1fr 100px}}