/* Chess Lessons — kid-friendly, clean */
:root{
  --cream:#f6f1e3;
  --blue:#5a7fb8;
  --blue-dark:#3e5f8f;
  --ink:#2b2b2b;
  --gold:#f2b134;
  --good:#2e9e5b;
  --card:#fffdf6;
}
*{box-sizing:border-box}
body{
  margin:0; font-family:"Avenir Next","Segoe UI",system-ui,-apple-system,sans-serif;
  background:var(--cream); color:var(--ink); line-height:1.55;
}
header.top{
  background:linear-gradient(135deg,var(--blue-dark),var(--blue));
  color:#fff; padding:14px 20px; position:sticky; top:0; z-index:50;
  box-shadow:0 2px 8px rgba(0,0,0,.15);
}
header.top .wrap{max-width:1000px;margin:0 auto;display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;font-size:1.25rem;color:#fff;text-decoration:none}
.brand img{width:44px;height:44px;border-radius:50%;background:#fff;object-fit:cover}
nav.mainnav{margin-left:auto;display:flex;gap:4px;flex-wrap:wrap}
nav.mainnav a{color:#fff;text-decoration:none;padding:8px 12px;border-radius:10px;font-weight:600}
nav.mainnav a:hover,nav.mainnav a.active{background:rgba(255,255,255,.22)}
main{max-width:1000px;margin:0 auto;padding:22px 16px 60px}
.hero{text-align:center;padding:26px 10px 10px}
.hero h1{margin:.2em 0;color:var(--blue-dark);font-size:2rem}
.hero p{max-width:640px;margin:0 auto;color:#4a4a4a}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:16px;margin-top:22px}
.pathcard{background:var(--card);border:2px solid var(--blue);border-radius:16px;padding:20px;text-decoration:none;color:inherit;display:block;transition:transform .12s}
.pathcard:hover{transform:translateY(-3px);box-shadow:0 6px 18px rgba(90,127,184,.25)}
.pathcard h2{margin:.1em 0 .3em;color:var(--blue-dark)}
.pathcard .tag{display:inline-block;background:var(--blue);color:#fff;font-size:.75rem;font-weight:700;border-radius:20px;padding:3px 10px;margin-bottom:8px}
.progress{height:10px;background:#e7dfc9;border-radius:6px;overflow:hidden;margin-top:10px}
.progress > div{height:100%;background:linear-gradient(90deg,var(--gold),var(--blue));width:0%;transition:width .4s}
.proglabel{font-size:.8rem;color:#666;margin-top:4px}
h2.section{color:var(--blue-dark);border-bottom:3px solid var(--blue);padding-bottom:6px;margin-top:34px}
.teach{background:var(--card);border-left:6px solid var(--gold);border-radius:10px;padding:14px 16px;margin:12px 0;box-shadow:0 1px 4px rgba(0,0,0,.06)}
.teach h3{margin:.1em 0 .3em;color:var(--blue-dark)}
.teach p{margin:.3em 0}
details.lesson{background:var(--card);border:1px solid #d9cfb4;border-radius:12px;margin:10px 0;overflow:hidden}
details.lesson summary{cursor:pointer;padding:14px 16px;font-weight:700;color:var(--blue-dark);background:#fbf7ea;list-style:none}
details.lesson summary::-webkit-details-marker{display:none}
details.lesson summary:before{content:"▶ ";color:var(--gold)}
details.lesson[open] summary:before{content:"▼ "}
details.lesson .body{padding:4px 16px 16px}
.exercise{background:#fff;border:2px solid var(--blue);border-radius:14px;padding:14px;margin:16px 0}
.exercise .exhead{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:8px}
.exercise .exhead .num{background:var(--blue);color:#fff;font-weight:800;border-radius:10px;padding:4px 12px}
.exercise .mission{font-weight:600;color:var(--blue-dark)}
.exercise.done{border-color:var(--good)}
.exercise.done .num{background:var(--good)}
.boardwrap{display:flex;gap:18px;flex-wrap:wrap;align-items:flex-start}
.board{position:relative;width:min(92vw,420px);aspect-ratio:1;display:grid;grid-template-columns:repeat(8,1fr);grid-template-rows:repeat(8,1fr);border:4px solid var(--blue-dark);border-radius:8px;overflow:hidden;user-select:none;touch-action:manipulation}
.sq{position:relative;display:flex;align-items:center;justify-content:center}
.sq.light{background:var(--cream)}
.sq.dark{background:var(--blue)}
.sq img{width:88%;height:88%;pointer-events:none}
.sq.sel{outline:4px solid var(--gold);outline-offset:-4px;z-index:2}
.sq.dest::after{content:"";position:absolute;inset:6%;border-radius:8px;background:rgba(242,177,52,.55);border:2px solid rgba(180,120,10,.7);pointer-events:none}
.sq.destcap::after{background:rgba(220,60,60,.5);border-color:rgba(150,20,20,.8)}
.sq.hintpulse::after{content:"";position:absolute;inset:6%;border-radius:8px;background:rgba(242,177,52,.75);animation:pulse 1s infinite;pointer-events:none}
@keyframes pulse{50%{opacity:.35}}
.sq .coord{position:absolute;font-size:9px;font-weight:700;opacity:.55;pointer-events:none}
.sq .coord.f{right:2px;bottom:1px}
.sq .coord.r{left:2px;top:1px}
.sq.light .coord{color:var(--blue-dark)}
.sq.dark .coord{color:#fff}
.sidepanel{flex:1;min-width:240px}
.status{min-height:2.2em;font-weight:600;color:var(--blue-dark);margin:6px 0}
.status.good{color:var(--good)}
.btn{background:var(--blue);color:#fff;border:none;border-radius:10px;padding:10px 16px;font-weight:700;cursor:pointer;font-size:1rem;margin:4px 6px 4px 0}
.btn:hover{background:var(--blue-dark)}
.btn.ghost{background:#fff;color:var(--blue-dark);border:2px solid var(--blue)}
.btn:disabled{opacity:.45;cursor:default}
.solved{background:#eaf7ef;border:2px solid var(--good);border-radius:12px;padding:12px 14px;margin-top:10px}
.solved .idea{font-size:1.15rem;font-weight:800;color:var(--good)}
.quiz{background:var(--card);border:1px solid #d9cfb4;border-radius:12px;padding:14px;margin:12px 0}
.quiz .q{font-weight:700;margin:8px 0}
.quiz .choice{display:block;width:100%;text-align:left;background:#fff;border:2px solid #d9cfb4;border-radius:10px;padding:9px 12px;margin:6px 0;cursor:pointer;font-size:1rem}
.quiz .choice:hover{border-color:var(--blue)}
.quiz .choice.right{border-color:var(--good);background:#eaf7ef}
.quiz .choice.wrong{border-color:#d23c3c;background:#fdeeee}
.quiz .explain{font-size:.92rem;color:#555;margin-top:6px}
footer{text-align:center;color:#777;font-size:.85rem;padding:26px 10px}
.promo-pick{position:absolute;z-index:10;background:#fff;border:3px solid var(--gold);border-radius:10px;padding:6px;display:flex;gap:6px;box-shadow:0 4px 14px rgba(0,0,0,.3)}
.promo-pick button{background:var(--cream);border:2px solid var(--blue);border-radius:8px;width:52px;height:52px;cursor:pointer;padding:4px}
.promo-pick button img{width:100%;height:100%}
.kbd-hint{font-size:.85rem;color:#666}