:root{--bg:#1f2430;--card:#272d3b;--fg:#e6e9ef;--muted:#9aa3b2;--accent:#6cb6ff;--ok:#54d18c;--bad:#ff6b6b;--line:#39414f}*{box-sizing:border-box}html,body{height:100%;margin:0}body{background:var(--bg);color:var(--fg);-webkit-font-smoothing:antialiased;font:17px/1.45 -apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif}#app{min-height:100%;padding:max(16px, env(safe-area-inset-top)) 16px calc(16px + env(safe-area-inset-bottom));justify-content:center;align-items:flex-start;display:flex}.card{background:var(--card);border:1px solid var(--line);border-radius:16px;outline:none;width:100%;max-width:480px;margin-top:6vh;padding:22px}h1{margin:0 0 4px;font-size:1.5rem}.muted{color:var(--muted)}.status{color:var(--muted);margin-bottom:14px;font-size:.85rem}.prompt{margin-bottom:18px;font-size:1.2rem;font-weight:600}.prompt.small{color:var(--muted);margin-bottom:10px;font-size:1rem;font-weight:500}.lbl{color:var(--muted);margin:14px 0 0;font-size:.9rem;display:block}.field{width:100%;color:var(--fg);border:1px solid var(--line);background:#1c2230;border-radius:10px;margin-top:6px;padding:12px;font-size:1rem;display:block}.boxrow{flex-wrap:wrap;gap:10px;margin-bottom:20px;display:flex}.boxrow.single{justify-content:flex-start}.numbox{text-align:center;width:56px;height:60px;color:var(--fg);border:2px solid var(--line);background:#1c2230;border-radius:12px;font-size:1.5rem}.numbox.wide{width:120px}.numbox:focus{border-color:var(--accent);outline:none}.btn{width:100%;color:var(--fg);border:1px solid var(--line);cursor:pointer;background:#313a4c;border-radius:12px;margin-top:12px;padding:15px;font-size:1.05rem;font-weight:600;display:block}.btn:active{transform:translateY(1px)}.btn.primary{background:var(--accent);color:#06223f;border-color:#0000}.btn.ghost{background:0 0}.btn.danger{color:var(--bad);border-color:var(--bad);background:0 0}.banner{border-radius:10px;margin-bottom:14px;padding:12px 14px;font-size:1.15rem;font-weight:700}.banner.ok{color:var(--ok);background:#54d18c26}.banner.bad{color:var(--bad);background:#ff6b6b26}.answer{margin-bottom:10px;font-size:1.1rem;font-weight:600}.explain{white-space:pre-wrap;color:var(--muted);border:1px solid var(--line);background:#1c2230;border-radius:10px;margin:0 0 6px;padding:12px;font-family:ui-monospace,SFMono-Regular,Menlo,monospace;font-size:.92rem;overflow-x:auto}