*,:after,:before{box-sizing:border-box;margin:0;padding:0}:root{--bg:#0f1117;--surface:#1a1d27;--border:#2a2d3d;--text:#e2e8f0;--muted:#718096;--accent:#4f8ef7;--green:#48bb78;--yellow:#ecc94b;--red:#fc8181;--radius:8px;--font:-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}body{background:var(--bg);color:var(--text);font-family:var(--font);font-size:15px;line-height:1.6}nav{background:var(--surface);border-bottom:1px solid var(--border);position:-webkit-sticky;position:sticky;top:0;z-index:100}.nav-inner{max-width:1200px;margin:0 auto;padding:0 1.5rem;height:56px;display:flex;align-items:center;gap:2rem}.nav-brand{font-weight:700;font-size:1.1rem;color:var(--accent);text-decoration:none}.nav-links{display:flex;gap:1.5rem}.nav-links a{color:var(--muted);text-decoration:none;font-size:.9rem;transition:color .15s}.nav-links a:hover{color:var(--text)}main{max-width:1200px;margin:0 auto;padding:2rem 1.5rem}a{color:var(--accent);text-decoration:none}a:hover{text-decoration:underline}h1{font-size:1.75rem;font-weight:700;margin-bottom:1rem}h2{font-size:1.25rem;margin-bottom:.75rem}h2,h3{font-weight:600}h3{font-size:1.05rem;margin-bottom:.5rem}.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem}.badge{display:inline-block;padding:2px 8px;border-radius:4px;font-size:.75rem;font-weight:600;text-transform:uppercase;letter-spacing:.05em}.badge-easy{background:#1a3a2a;color:var(--green)}.badge-medium{background:#3a3010;color:var(--yellow)}.badge-hard{background:#3a1a1a;color:var(--red)}.grid{display:grid;grid-gap:1rem;gap:1rem}.grid-2{grid-template-columns:repeat(auto-fill,minmax(300px,1fr))}.grid-4{grid-template-columns:repeat(auto-fill,minmax(200px,1fr))}.stat-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem}.stat-value{font-size:2rem;font-weight:700;color:var(--accent)}.stat-label{color:var(--muted);font-size:.85rem;margin-top:.25rem}.btn{display:inline-flex;align-items:center;gap:.5rem;padding:.5rem 1rem;border-radius:var(--radius);font-size:.9rem;font-weight:500;cursor:pointer;border:none;transition:opacity .15s}.btn:hover{opacity:.85}.btn-primary{background:var(--accent);color:#fff}.btn-ghost{background:transparent}.btn-ghost,input,select,textarea{border:1px solid var(--border);color:var(--text)}input,select,textarea{background:var(--bg);border-radius:var(--radius);padding:.5rem .75rem;font-family:inherit;font-size:.9rem}input:focus,select:focus,textarea:focus{outline:2px solid var(--accent);outline-offset:2px}.pagination{display:flex;gap:.5rem;align-items:center;justify-content:center;margin-top:2rem}