:root{--bg:#080c18;--panel:#111a33;--ink:#f5f7ff;--muted:#bdc7df;--cyan:#22d3ee;--yellow:#facc15;--violet:#8b5cf6;--line:#2b3d68}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--bg);color:var(--ink);font:17px/1.7 system-ui,-apple-system,"Segoe UI",Arial,sans-serif}header{background:linear-gradient(135deg,#101b3c,#29185b);border-bottom:1px solid var(--line)}.top,.wrap{width:min(950px,92%);margin:auto}.top{padding:2.8rem 0}.back{color:var(--cyan);text-decoration:none;font-weight:800}.kicker{margin-top:1.5rem;color:var(--yellow);font-weight:800;text-transform:uppercase;letter-spacing:.1em;font-size:.8rem}h1{font-size:clamp(2rem,6vw,3.8rem);line-height:1.08;margin:.4rem 0}.intro{max-width:760px;color:var(--muted);font-size:1.08rem}.wrap{padding:2rem 0 4rem}.summary{display:grid;grid-template-columns:repeat(3,1fr);gap:.7rem;margin-bottom:1.5rem}.summary a{background:#17254b;border:1px solid var(--line);border-radius:.7rem;padding:.75rem;text-decoration:none;text-align:center;font-weight:700}.lesson{background:var(--panel);border:1px solid var(--line);border-radius:1rem;padding:1.5rem;margin:1rem 0}.lesson h2{margin-top:0}.lesson h3{color:var(--cyan)}code{background:#050914;color:#a7f3d0;padding:.1rem .35rem;border-radius:.3rem}pre{background:#050914;color:#a7f3d0;border-left:4px solid var(--violet);padding:1rem;overflow:auto;border-radius:.4rem;white-space:pre-wrap}.task{border-left:4px solid var(--yellow);background:#facc150a;padding:.9rem 1rem;margin-top:1rem}.tip{color:var(--muted)}.ad{min-height:90px;margin:1.5rem auto}.next{display:flex;justify-content:space-between;gap:1rem;margin-top:2rem}.next a{color:var(--yellow);font-weight:800;text-decoration:none}footer{text-align:center;color:#7f8aa6;border-top:1px solid var(--line);padding:1.5rem}@media(max-width:650px){.summary{grid-template-columns:1fr}.lesson{padding:1rem}.next{display:block}.next a{display:block;margin:.7rem 0}}