:root{--bg:#f6f5f0;--surface:#ffffff;--surface-2:#f0efe8;--text:#1c1f1d;--muted:#5d6460;--line:#dedcd2;--brand:#0b7a4b;--brand-ink:#ffffff;--brand-soft:#e3f2ea;--accent:#f2c230;--accent-soft:#fdf3cf;--ok:#157f3d;--ok-soft:#e2f4e8;--bad:#c0362c;--bad-soft:#fbe7e5;--warn:#9a6a00;--warn-soft:#fff4d6;--radius:14px;--shadow:0 1px 2px rgba(0,0,0,0.05),0 4px 16px rgba(0,0,0,0.04);color-scheme:light}@media (prefers-color-scheme:dark){:root{--bg:#121513;--surface:#1b1f1d;--surface-2:#232825;--text:#e8ebe9;--muted:#a0a8a3;--line:#2f3632;--brand:#3fbf84;--brand-ink:#0b1a12;--brand-soft:#193326;--accent:#f2c230;--accent-soft:#3a3115;--ok:#4cc77a;--ok-soft:#173322;--bad:#f07167;--bad-soft:#3a1c1a;--warn:#f0c45a;--warn-soft:#3a3115;--shadow:none;color-scheme:dark}}*{box-sizing:border-box}body,html{margin:0;padding:0}body{background:var(--bg);color:var(--text);font:16px/1.55 -apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,sans-serif;-webkit-font-smoothing:antialiased}a{color:var(--brand);text-decoration:none}h1,h2,h3{line-height:1.25;margin:0 0 .5em}h1{font-size:1.6rem}h2{font-size:1.25rem}h3{font-size:1.05rem}p{margin:0 0 .8em}.wrap{max-width:860px;margin:0 auto;padding:16px}.top{position:-webkit-sticky;position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}.top .wrap{gap:12px;padding-top:10px;padding-bottom:10px}.logo,.top .wrap{display:flex;align-items:center}.logo{font-weight:700;color:var(--text);gap:8px}.logo .flag{width:26px;height:26px;border-radius:7px;background:var(--brand);display:grid;place-items:center}.logo .flag i{width:12px;height:12px;background:var(--accent);transform:rotate(45deg);border-radius:2px}.nav{display:flex;gap:4px;margin-left:auto;flex-wrap:wrap}.nav a,.nav button{font:inherit;font-size:.9rem;color:var(--muted);padding:6px 10px;border-radius:999px;border:0;background:none;cursor:pointer}.nav a:hover,.nav button:hover{background:var(--surface-2);color:var(--text)}@media (max-width:640px){.nav .hide-sm{display:none}}.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px;box-shadow:var(--shadow);margin-bottom:14px}.grid{display:grid;grid-gap:14px;gap:14px;grid-template-columns:repeat(auto-fill,minmax(240px,1fr))}.tile{display:block;color:var(--text);transition:transform .12s ease,border-color .12s}.tile:hover{transform:translateY(-2px);border-color:var(--brand)}.tile .ico{font-size:1.6rem}.tile h2{margin-top:6px}.muted{color:var(--muted)}.small{font-size:.88rem}.row{display:flex;gap:10px;align-items:center;flex-wrap:wrap}.spacer{flex:1 1}.btn{font:inherit;font-weight:600;border:1px solid var(--brand);background:var(--brand);color:var(--brand-ink);padding:10px 16px;border-radius:10px;cursor:pointer;display:inline-flex;align-items:center;gap:6px}.btn:disabled{opacity:.5;cursor:default}.btn.ghost{background:transparent;color:var(--brand)}.btn.sm{padding:6px 10px;font-size:.88rem}.btn.full{width:100%;justify-content:center}input[type=password],input[type=text],select,textarea{font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:10px 12px;width:100%}input:focus,select:focus,textarea:focus{outline:2px solid color-mix(in srgb,var(--brand) 40%,transparent);border-color:var(--brand)}label{display:block;font-weight:600;margin:10px 0 6px}textarea{min-height:120px;resize:vertical}input.gap{display:inline-block;width:9.5em;max-width:100%;padding:4px 8px;margin:2px 3px;border:0;border-bottom:2px solid var(--brand);border-radius:6px 6px 0 0;background:var(--brand-soft);font:inherit;color:var(--text)}input.gap.wide{width:100%;display:block;margin:6px 0}.gap.ok{border-color:var(--ok);background:var(--ok-soft)}.gap.bad{border-color:var(--bad);background:var(--bad-soft)}.gap.accent{border-color:var(--warn);background:var(--warn-soft)}.hint-verb{color:var(--muted);font-size:.9em}.story{line-height:2.3;white-space:pre-wrap}.badge{display:inline-block;font-size:.78rem;font-weight:700;padding:2px 8px;border-radius:999px;background:var(--surface-2);color:var(--muted)}.badge.ok{background:var(--ok-soft);color:var(--ok)}.badge.bad{background:var(--bad-soft);color:var(--bad)}.badge.warn{background:var(--warn-soft);color:var(--warn)}.badge.brand{color:var(--brand)}.badge.brand,.sol{background:var(--brand-soft)}.sol{margin:6px 0 10px;padding:10px 12px;border-left:3px solid var(--brand);border-radius:0 10px 10px 0;font-size:.93rem}.sol b{color:var(--brand)}.tip{background:var(--brand-soft)}.tip,.warnbox{padding:12px 14px;border-radius:12px;margin:10px 0}.warnbox{background:var(--warn-soft)}.analogy{display:grid;grid-gap:8px;gap:8px;margin:10px 0}.analogy div{display:flex;gap:10px;align-items:flex-start;background:var(--surface-2);padding:10px 12px;border-radius:10px}.analogy .lang{font-weight:800;font-size:.75rem;background:var(--accent);color:#2b2200;border-radius:6px;padding:2px 6px;flex:none;margin-top:2px}.tbl{width:100%;border-collapse:collapse;margin:10px 0;font-size:.93rem}.tbl td,.tbl th{border-bottom:1px solid var(--line);padding:8px 6px;text-align:left;vertical-align:top}.tbl th{color:var(--muted);font-weight:600;font-size:.82rem;text-transform:uppercase;letter-spacing:.02em}.tbl td.irr{background:var(--accent-soft);font-weight:700}.scroll-x{overflow-x:auto;-webkit-overflow-scrolling:touch}.chips{display:flex;flex-wrap:wrap;gap:6px;margin:6px 0 10px}.chip{font:inherit;border:1px solid var(--line);background:var(--surface);color:var(--text);padding:4px 10px;border-radius:999px;cursor:pointer}.chip.on{background:var(--brand);color:var(--brand-ink);border-color:var(--brand)}.chip.should{outline:2px dashed var(--ok)}.chip.wrongsel{background:var(--bad);border-color:var(--bad);color:#fff}.accentbar{position:fixed;left:0;right:0;bottom:0;z-index:30;background:var(--surface);border-top:1px solid var(--line);display:flex;gap:4px;justify-content:center;padding:8px;flex-wrap:wrap}.accentbar button{font:inherit;font-size:1.05rem;min-width:38px;padding:6px 8px;border-radius:8px;border:1px solid var(--line);background:var(--surface-2);color:var(--text);cursor:pointer}.pad-bottom{padding-bottom:90px}.score{font-size:2.6rem;font-weight:800}.bar{height:10px;background:var(--surface-2);border-radius:999px;overflow:hidden}.bar>i{display:block;height:100%;background:var(--brand)}.hr{height:1px;background:var(--line);margin:14px 0}.center{text-align:center}.login{max-width:380px;margin:8vh auto}.err{color:var(--bad);background:var(--bad-soft);padding:10px 12px;border-radius:10px;margin:10px 0}.diff ins{background:var(--ok-soft);color:var(--ok);text-decoration:none}.diff del,.diff ins{padding:0 2px;border-radius:4px}.diff del{background:var(--bad-soft);color:var(--bad)}.qa{margin:14px 0}.drill-q{font-size:1.25rem;margin:10px 0 14px}.drill-input{font-size:1.2rem}.sticky-submit{position:-webkit-sticky;position:sticky;bottom:70px;z-index:10}.ex{margin:0 0 14px;padding-left:10px;border-left:3px solid var(--line)}.ex-pt{font-weight:700}.ex-tr{color:var(--brand);margin:2px 0}.boxes{display:grid;grid-gap:10px;gap:10px;grid-template-columns:repeat(auto-fill,minmax(220px,1fr))}.box{background:var(--surface-2);border-radius:12px;padding:12px;border-top:4px solid var(--brand)}.box-head{font-weight:800;font-size:1.05rem}.box-tr{color:var(--brand);font-weight:600;margin:4px 0 6px}.steps{padding-left:22px;margin:6px 0 12px}.steps li{margin-bottom:8px}