:root{color-scheme:light;--ink:#17202a;--muted:#5f6f7c;--line:#d8e0e7;--panel:#ffffff;--bg:#f4f7f5;--accent:#0f7a78;--accent-2:#a8452d}*{box-sizing:border-box}body{margin:0;font-family:Arial,Helvetica,sans-serif;color:var(--ink);background:var(--bg)}a{color:inherit}button,input,select,textarea{font:inherit}.shell{min-height:100vh;display:grid;grid-template-columns:280px 1fr}.nav{background:#17313b;color:white;padding:24px}.nav h1{font-size:24px;line-height:1.1;margin:0 0 28px}.nav a,.nav form button{display:block;width:100%;color:white;text-align:left;text-decoration:none;background:transparent;border:0;border-radius:6px;padding:10px 12px;margin:4px 0;cursor:pointer}.nav a:hover,.nav form button:hover{background:rgba(255,255,255,.12)}.main{padding:32px}.grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));grid-gap:16px;gap:16px}.card,.panel{background:var(--panel);border:1px solid var(--line);border-radius:8px;padding:18px}.card h3,.panel h2{margin-top:0}.muted{color:var(--muted)}.badge{display:inline-flex;align-items:center;min-height:24px;border-radius:999px;padding:2px 9px;background:#e6f0ef;color:#0b5553;font-size:12px}.danger{color:var(--accent-2)}.form{display:grid;grid-gap:12px;gap:12px;max-width:720px}.form label{display:grid;grid-gap:6px;gap:6px}.form input,.form select,.form textarea{border:1px solid var(--line);border-radius:6px;padding:10px}.button{border:0;border-radius:6px;padding:10px 14px;background:var(--accent);color:white;cursor:pointer;text-decoration:none;display:inline-block}.button.secondary{background:#314b57}.lesson{max-width:900px;display:grid;grid-gap:16px;gap:16px}.question{font-size:22px;line-height:1.45}@media (max-width:760px){.shell{grid-template-columns:1fr}.nav{position:static}}