:root{--bg:#080f20;--panel:#121d35;--line:#314262;--muted:#c0ccdf;--ink:#f4f8ff;--mint:#83ead0;--purple:#a99aff;--amber:#ffd07a}*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;color:var(--ink);background:radial-gradient(ellipse at 85% 0%,#20294c,transparent 45%),var(--bg);font:16px/1.6 system-ui,Segoe UI,sans-serif}a{color:var(--mint)}header,footer{display:flex;justify-content:space-between;gap:1rem;padding:1.1rem max(4%,calc((100vw - 1240px)/2));border-bottom:1px solid var(--line)}header a{text-decoration:none}.brand{font-weight:800;color:var(--ink)}main{max-width:1240px;margin:auto;padding:0 24px 40px}.hero{padding:45px 0 24px}.hero h1{font-size:clamp(2.7rem,7vw,4.7rem);line-height:1.05;letter-spacing:-.04em;margin:12px 0 20px}.hero>p{max-width:750px;color:var(--muted);font-size:1.15rem}.eyebrow{color:var(--mint);font-size:.8rem;letter-spacing:.08em;text-transform:uppercase;font-weight:800}.progress{display:flex;align-items:center;gap:20px;flex-wrap:wrap}#lessons{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:20px 0 32px}#lessons button{text-align:left;background:var(--panel);border:1px solid var(--line);padding:18px;border-radius:12px;color:var(--ink)}#lessons button.active{border-color:var(--mint);background:#19393e}#lessons button span{display:block;font-size:.82rem;font-weight:400;color:var(--muted);margin-top:5px}#lessons button strong{color:var(--mint);margin-right:8px}.panel{background:var(--panel);padding:24px;border:1px solid var(--line);border-radius:14px;min-width:0}.lesson-head{margin-bottom:20px}.lesson-head h2{font-size:2rem;margin:8px 0}.lesson-head p{color:var(--muted)}.columns{display:grid;grid-template-columns:1.35fr 1fr;gap:20px}.panel h3{margin:0 0 14px}.panel p{overflow-wrap:anywhere}ol{padding-left:22px}li{padding:0 0 12px;color:var(--muted)}label{display:block;font-weight:650;margin-bottom:7px}input,textarea,select{background:#091225;color:var(--ink);border:1px solid #506384;border-radius:8px;padding:11px;width:100%;font:inherit}input[type=radio]{width:auto;accent-color:var(--mint);margin-right:10px}textarea{resize:vertical;min-height:90px}#code{font:14px/1.6 Consolas,monospace;min-height:460px;tab-size:4;white-space:pre}input:focus,textarea:focus,select:focus{outline:2px solid var(--mint);outline-offset:2px}.field{margin-bottom:14px}.row{display:grid;grid-template-columns:1fr 1fr;gap:12px}.actions{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0 5px}button{background:var(--mint);color:#081f25;font:700 14px/1.4 system-ui;border:1px solid transparent;border-radius:8px;padding:11px 15px;cursor:pointer}button:hover{filter:brightness(1.1)}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid var(--amber);outline-offset:3px}button.secondary{background:#273655;color:var(--ink);border-color:#506384}button.quiet{background:transparent;color:var(--muted);border-color:var(--line)}button:disabled{opacity:.5;cursor:default}button[hidden]{display:none}.status{color:var(--mint);min-height:26px}.status.error,#feedback.error{color:#ffafb2}.metrics{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin:18px 0}.metric{padding:14px;border-radius:8px;background:#091225;border:1px solid var(--line)}.metric b{display:block;font-size:1.6rem;color:var(--mint)}.metric span{color:var(--muted);font-size:.85rem}.table-wrap{overflow:auto;margin-top:16px}table{border-collapse:collapse;width:100%;font-size:.87rem}td,th{text-align:left;padding:9px;border-bottom:1px solid var(--line)}th{color:var(--muted);white-space:nowrap}tr.current{background:#22423e}.code-panel{margin:24px 0}.section-title{display:flex;justify-content:space-between;gap:15px;align-items:start}.section-title h2{margin:0}.section-title p{color:var(--muted);max-width:800px;font-size:.9rem}.small{font-size:.85rem;color:var(--muted)}pre{margin:0;background:#071020;padding:16px;border:1px solid var(--line);border-radius:8px;white-space:pre-wrap;overflow-wrap:anywhere;font:14px/1.6 Consolas,monospace;max-height:440px;overflow:auto}#console{min-height:150px}details{border-top:1px solid var(--line);padding-top:16px}summary{cursor:pointer;font-weight:700;color:var(--mint)}#answers label{font-weight:400;padding:10px;background:#091225;border:1px solid var(--line);border-radius:7px;margin-bottom:8px}svg{display:block;width:100%;height:auto;background:#081225;border-radius:10px;margin-top:20px}.stack{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:18px 0}.stack span{padding:12px 16px;background:#243c51;border:1px solid var(--mint);font:700 22px Consolas,monospace;border-radius:7px}.stack .top{background:#375256;border-color:var(--amber)}.ad{overflow:hidden;margin-top:24px}footer{border-top:1px solid var(--line);color:var(--muted);font-size:.85rem}.skip{position:absolute;left:-9999px}.skip:focus{left:20px;top:20px;padding:12px;background:white;color:black;z-index:20}@media(max-width:850px){.columns{grid-template-columns:1fr}#lessons{grid-template-columns:repeat(2,1fr)}.section-title{flex-direction:column}header,footer{flex-wrap:wrap}}@media(max-width:480px){main{padding:0 14px 30px}.panel{padding:17px}#lessons{gap:8px}#lessons button{padding:12px;font-size:13px}.row{grid-template-columns:1fr}.lesson-head h2{font-size:1.6rem}#code{font-size:13px}.hero{padding-top:30px}}
@media print{header,#lessons,.actions,.code-panel,.ad,footer{display:none}body{background:white;color:black}.panel{border:1px solid #bbb;background:white}.columns{display:block}.panel{margin-bottom:14px}.status,li,.small,.lesson-head p{color:black}}