:root{--bg:#f8fafc;--fg:#0f172a;--muted:#64748b;--card:#fff;--line:#e2e8f0;--accent:#2563eb;--accent-fg:#fff;--aux:#1d4ed8;--aux-bg:#dbeafe;--verb:#15803d;--verb-bg:#dcfce7;--neg:#b45309;--neg-bg:#fef3c7;--subj:#475569;--subj-bg:#f1f5f9;--ok:#15803d;--ok-bg:#f0fdf4;--bad:#b91c1c;--bad-bg:#fef2f2}@media (prefers-color-scheme:dark){:root{--bg:#0b1120;--fg:#e2e8f0;--muted:#94a3b8;--card:#131c31;--line:#263148;--accent:#3b82f6;--aux:#93c5fd;--aux-bg:#1e3a8a66;--verb:#86efac;--verb-bg:#14532d66;--neg:#fcd34d;--neg-bg:#78350f66;--subj:#cbd5e1;--subj-bg:#33415566;--ok:#86efac;--ok-bg:#14532d44;--bad:#fca5a5;--bad-bg:#7f1d1d44}}*{box-sizing:border-box}body{background:var(--bg);color:var(--fg);margin:0;font:16px/1.5 system-ui,-apple-system,Segoe UI,Roboto,sans-serif}header{background:var(--card);border-bottom:1px solid var(--line);z-index:1;flex-wrap:wrap;justify-content:space-between;align-items:center;gap:8px 16px;padding:10px 16px;display:flex;position:sticky;top:0}.brand small{color:var(--accent)}nav{gap:4px;display:flex}nav a{color:var(--muted);border-radius:8px;padding:6px 12px;font-weight:600;text-decoration:none}nav a[aria-current]{background:var(--accent);color:var(--accent-fg)}main{max-width:860px;margin:0 auto;padding:16px 16px 48px}h1{margin:8px 0 12px;font-size:1.5rem}h2{margin:20px 0 8px;font-size:1.15rem}small{color:var(--muted);font-weight:400}button{font:inherit;cursor:pointer;border:1px solid var(--line);background:var(--card);color:var(--fg);border-radius:8px;padding:8px 14px}button:disabled{cursor:default;opacity:.6}button.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-fg);font-weight:600}button.danger{background:var(--bad);border-color:var(--bad);color:#fff}:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.formula{font-family:ui-monospace,SF Mono,Menlo,Consolas,monospace;font-size:.95em;line-height:2}.plus{color:var(--muted)}.tok{white-space:nowrap;border-radius:6px;padding:2px 7px;font-weight:600}.tok.subj{background:var(--subj-bg);color:var(--subj)}.tok.aux{background:var(--aux-bg);color:var(--aux)}.tok.verb{background:var(--verb-bg);color:var(--verb)}.tok.neg{background:var(--neg-bg);color:var(--neg)}.tok.blank{border:2px dashed var(--muted);color:var(--muted);padding:0 14px}.tok.punct{padding:0 2px}.legend{color:var(--muted);margin:4px 0 12px;font-size:.9rem}.verbs,.stats{border-collapse:collapse;width:100%;margin:8px 0 16px}.verbs caption{text-align:left;padding-bottom:4px;font-weight:600}.verbs th,.verbs td,.stats th,.stats td{text-align:left;border-bottom:1px solid var(--line);padding:6px 10px}.verbs{background:var(--card);border-radius:8px}.tabs{gap:6px;margin:12px 0;display:flex}.tabs button{flex:1}.tabs button.on{background:var(--accent);border-color:var(--accent);color:var(--accent-fg)}.tabs button.on small{color:inherit;opacity:.85}.cards{gap:14px;display:grid}.card{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:14px 16px}.card h2{margin:0}.use{color:var(--muted);margin:2px 0 8px;font-size:.92rem}.forms{font-family:ui-monospace,Menlo,Consolas,monospace}.ftable{border-collapse:collapse;width:100%}.ftable th{text-align:left;color:var(--muted);white-space:nowrap;vertical-align:top;width:1%;padding:6px 10px 6px 0;font-size:.85rem;font-weight:600}.ftable td{border-top:1px solid var(--line);padding:4px 0}.ftable th{border-top:1px solid var(--line)}.tip{margin:8px 0 0;font-size:.9rem}.example{border-left:3px solid var(--accent);margin:10px 0 0;padding-left:10px}fieldset{border:1px solid var(--line);background:var(--card);border-radius:12px;margin:0 0 16px;padding:8px 12px}legend{padding:0 6px;font-weight:600}.choice{cursor:pointer;align-items:flex-start;gap:10px;padding:8px 0;display:flex}.choice input{margin-top:6px}.field{gap:4px;margin-bottom:16px;font-weight:600;display:grid}select{font:inherit;border:1px solid var(--line);background:var(--card);color:var(--fg);border-radius:8px;padding:8px}.count{color:var(--muted);margin:0}.prompt{font-size:1.15rem}.big{margin:4px 0;font-size:1.25rem;font-weight:700}.options{gap:10px;margin:8px 0 16px;display:grid}.option{text-align:left;align-items:center;gap:10px;padding:12px 14px;font-size:1rem;display:flex}kbd{text-align:center;border:1px solid var(--line);min-width:1.6em;color:var(--muted);border-radius:6px;flex:none;padding:0 6px;font:.8rem ui-monospace,Menlo,Consolas,monospace}.hint{color:var(--muted);margin:0 0 8px;font-size:.85rem}@media (pointer:coarse){.hint{display:none}}.option.right{border-color:var(--ok);background:var(--ok-bg);opacity:1}.option.wrong{border-color:var(--bad);background:var(--bad-bg);opacity:1}.feedback{border:1px solid var(--line);background:var(--card);border-radius:12px;padding:4px 16px 14px}.feedback.right{border-color:var(--ok)}.feedback.wrong{border-color:var(--bad)}.feedback p{margin:6px 0}.result{text-align:center}.score{color:var(--accent);margin:0;font-size:3rem;font-weight:700}.actions{gap:8px;max-width:320px;margin:16px auto 0;display:grid}.summary{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:10px 14px}.bar{background:var(--line);border-radius:10px;width:100%;min-width:90px;height:20px;display:block;position:relative;overflow:hidden}.bar i{background:var(--ok);opacity:.55;position:absolute;inset:0 auto 0 0}.bar b{padding-left:8px;font-size:.8rem;line-height:20px;position:relative}.attempts{color:var(--muted);padding-left:18px}.reset{flex-wrap:wrap;align-items:center;gap:8px;margin-top:24px;display:flex}@media (width>=640px){.actions{grid-template-columns:1fr 1fr;max-width:520px}}.scroll{border:1px solid var(--line);background:var(--card);border-radius:12px;overflow-x:auto}.summary-table{border-collapse:collapse;width:100%;min-width:880px;font-size:.9rem}.summary-table th,.summary-table td{text-align:left;border-bottom:1px solid var(--line);vertical-align:top;padding:6px 10px}.summary-table thead th{background:var(--card);position:sticky;top:0}.summary-table tbody th[scope=row]{white-space:nowrap}.summary-table .group-row th{background:var(--subj-bg);color:var(--fg)}.tabs{flex-wrap:wrap}.tabs button{min-width:6.5rem}.stats td.low{background:var(--bad-bg);color:var(--bad);font-weight:600}.stats th,.stats td{padding:6px 8px}button.tok{font:inherit;cursor:pointer;border:0;padding:2px 7px;font-family:ui-monospace,SF Mono,Menlo,Consolas,monospace;font-weight:600}.sentence button.tok{font-family:inherit}.tok.hl{outline:2px solid var(--accent);outline-offset:1px}.tok.dim{opacity:.45}.tok.diff{box-shadow:0 2px 0 0 var(--neg)}.muted{color:var(--muted)}.sentence{line-height:2}.toggle{cursor:pointer;align-items:center;gap:8px;margin:4px 0 12px;display:flex}.rowbtn{color:var(--muted);text-align:left;background:0 0;border-color:#0000;padding:2px 6px;font-size:.85rem;font-weight:600}.rowbtn[aria-pressed=true]{color:var(--accent);border-color:var(--accent)}.reveal{color:var(--muted);border-style:dashed;padding:4px 12px;font-size:.9rem}.ftable tr.sel td{background:var(--subj-bg)}.timeline{width:100%;max-width:320px;height:auto;margin:4px 0 8px;display:block}.timeline text{fill:var(--muted);font-size:10px}.tl-axis,.tl-now{stroke:var(--muted);stroke-width:1.5px}.tl-now{stroke-dasharray:3 3}.tl-ref{stroke:var(--neg);stroke-width:2px}.tl-act{fill:var(--accent)}.tl-arrow{stroke:var(--accent);stroke-width:2px}.tl-head{fill:var(--accent)}.grid{border-collapse:separate;border-spacing:6px;width:100%;min-width:640px}.grid th{text-align:left;vertical-align:middle;font-size:.85rem}.grid td button{text-align:left;width:100%;padding:6px 8px}.grid td button.on{border-color:var(--accent);background:var(--aux-bg)}.steps{gap:8px;padding-left:0;list-style:none;display:grid}.pairs{flex-wrap:wrap;gap:6px;margin-bottom:10px;display:flex}.pairs button{padding:4px 10px;font-size:.85rem}.pairs button.on{background:var(--accent);border-color:var(--accent);color:var(--accent-fg)}.pick{grid-template-columns:1fr 1fr;gap:8px;margin-bottom:12px;display:grid}.compare{min-width:0}.cards.two{grid-template-columns:1fr 1fr;margin-top:14px}@media (width<=640px){.cards.two,.pick{grid-template-columns:1fr}}.helper{color:var(--muted);margin:8px 0 0;font-size:.85rem}