/* Chess Checkmate. Palette: ebony + ivory + copper (unique; no gold/teal/pink). */
:root{
  --bg:#f4efe4; --surface:#ffffff; --surface2:#ece4d3; --text:#1c1b1f; --muted:#5d5a55; --line:#d8ccb6;
  --accent:#c4703a; --accent-ink:#ffffff; --accent-soft:#f6e2d3; --good:#2f7d4f; --bad:#b33a3a;
  --sq-light:#ecd8b6; --sq-dark:#a97a4f; --sq-last:rgba(196,112,58,.45); --sq-sel:rgba(196,112,58,.6); --sq-check:rgba(220,40,40,.75);
  --shadow:0 6px 24px rgba(30,20,10,.12); --radius:14px;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#141518; --surface:#1d1f24; --surface2:#25282e; --text:#efe8da; --muted:#a8a197; --line:#33363d;
  --accent:#d98447; --accent-ink:#141518; --accent-soft:#3a2a1f; --good:#5cc489; --bad:#ef6b6b; --shadow:0 6px 24px rgba(0,0,0,.4); color-scheme:dark;}}
:root[data-theme="dark"]{
  --bg:#141518; --surface:#1d1f24; --surface2:#25282e; --text:#efe8da; --muted:#a8a197; --line:#33363d;
  --accent:#d98447; --accent-ink:#141518; --accent-soft:#3a2a1f; --good:#5cc489; --bad:#ef6b6b; --shadow:0 6px 24px rgba(0,0,0,.4); color-scheme:dark;}
:root[data-board="ocean"]{--sq-light:#dfe6ec; --sq-dark:#6f8aa3}
:root[data-board="marble"]{--sq-light:#e8e8e4; --sq-dark:#8f8f8a}
:root[data-board="tournament"]{--sq-light:#eeeed2; --sq-dark:#6f9a52}
:root[data-board="ebony"]{--sq-light:#d9c9b0; --sq-dark:#3f3a36}

*{box-sizing:border-box}
html,body{margin:0;background:var(--bg);color:var(--text);font:16px/1.5 "Inter",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;-webkit-text-size-adjust:100%}
a{color:var(--accent)}
img{max-width:100%}
.wrap{max-width:1180px;margin:0 auto;padding:0 16px}
header.top{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
header.top .wrap{display:flex;align-items:center;gap:12px;min-height:58px;flex-wrap:wrap}
.brand{display:flex;align-items:center;gap:9px;font-weight:800;font-size:1.12rem;color:var(--text);text-decoration:none;letter-spacing:.2px}
.brand svg{width:30px;height:30px}
.brand b{color:var(--accent)}
nav.main{display:flex;gap:4px;flex-wrap:wrap;margin-left:auto}
nav.main a{color:var(--text);text-decoration:none;padding:7px 10px;border-radius:9px;font-weight:600;font-size:.94rem}
nav.main a:hover,nav.main a[aria-current]{background:var(--surface2)}
.top .menu-btn{display:none;margin-left:auto}
@media (max-width:760px){nav.main{display:none;width:100%;margin:0 0 8px}nav.main.open{display:flex}.top .menu-btn{display:inline-flex}}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:1px solid var(--line);background:var(--surface);color:var(--text);padding:9px 13px;border-radius:10px;font:600 .93rem/1 inherit;cursor:pointer;text-decoration:none;min-height:40px}
.btn:hover{border-color:var(--accent)}
.btn.primary{background:var(--accent);border-color:var(--accent);color:var(--accent-ink)}
.btn.small{padding:6px 9px;min-height:32px;font-size:.85rem}
.btn:disabled{opacity:.45;cursor:not-allowed}
select,input,textarea{font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--line);border-radius:9px;padding:8px 10px;max-width:100%}
textarea{width:100%;min-height:90px}
footer.foot{border-top:1px solid var(--line);margin-top:48px;padding:26px 0 40px;color:var(--muted);font-size:.9rem}
footer.foot .wrap{display:flex;flex-wrap:wrap;gap:14px 26px;justify-content:space-between}
footer.foot a{color:var(--muted)}

/* hero + cards */
.hero{padding:34px 0 10px;display:grid;grid-template-columns:1.1fr .9fr;gap:30px;align-items:center}
.hero h1{font-size:clamp(2rem,5vw,3.2rem);line-height:1.08;margin:0 0 12px;letter-spacing:-.5px}
.hero p{color:var(--muted);font-size:1.08rem;margin:0 0 20px}
@media (max-width:820px){.hero{grid-template-columns:1fr}}
.cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:14px;margin:26px 0}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px;text-decoration:none;color:var(--text);box-shadow:var(--shadow);transition:transform .15s}
.card:hover{transform:translateY(-2px);border-color:var(--accent)}
.card h3{margin:6px 0 4px;font-size:1.1rem}
.card p{margin:0;color:var(--muted);font-size:.93rem}
.card .ic{font-size:1.6rem}

/* game layout */
.game{display:grid;grid-template-columns:minmax(0,1fr) 330px;gap:18px;padding:16px 0;align-items:start}
@media (max-width:900px){.game{grid-template-columns:1fr}}
.boardcol{display:flex;flex-direction:column;gap:8px;min-width:0;width:100%;max-width:min(640px,calc(100vh - 150px));margin:0 auto}
@media (max-width:900px){.boardcol{max-width:640px}}
.player{display:flex;align-items:center;justify-content:space-between;gap:10px;background:var(--surface);border:1px solid var(--line);border-radius:10px;padding:7px 11px;min-height:44px}
.player .name{font-weight:700}
.player .caps{font-size:1.05rem;letter-spacing:-2px;color:var(--muted);min-height:1em}
.player .caps small{letter-spacing:0;margin-left:6px;font-size:.8rem}
.clock{font:700 1.2rem/1 ui-monospace,Consolas,monospace;background:var(--surface2);padding:7px 10px;border-radius:8px;min-width:80px;text-align:center}
.clock.on{background:var(--accent);color:var(--accent-ink)}
.clock.low{background:var(--bad);color:#fff}
.side{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:14px;display:flex;flex-direction:column;gap:12px;box-shadow:var(--shadow)}
.side h2{margin:0;font-size:1.05rem}
.row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.status{font-weight:700;padding:9px 11px;border-radius:9px;background:var(--accent-soft)}
.status.over{background:var(--accent);color:var(--accent-ink)}
.moves{max-height:260px;overflow:auto;display:grid;grid-template-columns:34px 1fr 1fr;font-size:.93rem;border:1px solid var(--line);border-radius:9px}
.moves div{padding:4px 7px}
.moves .n{color:var(--muted);background:var(--surface2)}
.moves .mv{cursor:pointer}
.moves .mv.cur{background:var(--accent-soft);font-weight:700}
.muted{color:var(--muted)}
label.inline{display:flex;gap:6px;align-items:center;font-size:.92rem}

/* board */
.board-wrap{position:relative;width:100%;margin:0 auto;display:flex;gap:6px}
.board{position:relative;width:100%;aspect-ratio:1;display:grid;grid-template-columns:repeat(8,1fr);grid-template-rows:repeat(8,1fr);border-radius:6px;overflow:hidden;box-shadow:var(--shadow);user-select:none;-webkit-user-select:none;touch-action:none}
.sq{position:relative;background:var(--sq-light)}
.sq.d{background:var(--sq-dark)}
.sq.last::after,.sq.sel::after,.sq.chk::after,.sq.hint::after{content:"";position:absolute;inset:0}
.sq.last::after{background:var(--sq-last)}
.sq.sel::after{background:var(--sq-sel)}
.sq.chk::after{background:radial-gradient(circle,var(--sq-check) 0%,rgba(220,40,40,.35) 55%,transparent 75%)}
.sq.hint::after{background:rgba(47,125,79,.45)}
.sq .dot{position:absolute;left:50%;top:50%;width:30%;height:30%;margin:-15% 0 0 -15%;border-radius:50%;background:rgba(20,20,20,.22);z-index:3;pointer-events:none}
.sq .ring{position:absolute;inset:4%;border-radius:50%;border:5px solid rgba(20,20,20,.22);z-index:3;pointer-events:none}
.sq img.pc{position:absolute;inset:0;width:100%;height:100%;z-index:2;cursor:grab;-webkit-user-drag:none}
.sq .co{position:absolute;font-size:clamp(8px,1.5vw,12px);font-weight:700;z-index:1;opacity:.8;pointer-events:none}
.sq .co.f{right:3px;bottom:1px}.sq .co.r{left:3px;top:1px}
.sq.d .co{color:var(--sq-light)}.sq:not(.d) .co{color:var(--sq-dark)}
img.drag{position:fixed;z-index:100;pointer-events:none;width:80px;height:80px;transform:translate(-50%,-50%) scale(1.08);filter:drop-shadow(0 6px 8px rgba(0,0,0,.35))}
.promo{position:absolute;inset:0;background:rgba(0,0,0,.45);z-index:30;display:flex;align-items:center;justify-content:center}
.promo div{background:var(--surface);border-radius:12px;padding:10px;display:flex;gap:6px;box-shadow:var(--shadow)}
.promo button{width:64px;height:64px;border:1px solid var(--line);border-radius:10px;background:var(--surface2);cursor:pointer;padding:4px}
.promo button img{width:100%;height:100%}
.evalbar{width:22px;border-radius:6px;overflow:hidden;background:#2b2b2b;position:relative;flex:none;box-shadow:var(--shadow)}
.evalbar .w{position:absolute;left:0;right:0;bottom:0;background:#f2f2ef;transition:height .3s}
.evalbar span{position:absolute;left:0;right:0;font:700 9px/1 sans-serif;text-align:center;z-index:2;color:#888}
.overlay{position:fixed;inset:0;background:rgba(0,0,0,.45);z-index:50;display:none;align-items:center;justify-content:center;padding:16px}
.overlay.show{display:flex}
.overlay .box{background:var(--surface);border-radius:var(--radius);padding:22px;max-width:380px;width:100%;text-align:center;box-shadow:var(--shadow)}
.overlay h2{margin:0 0 6px}

/* articles */
article.learn{max-width:820px;margin:0 auto;padding:22px 0}
article.learn h1{font-size:clamp(1.8rem,4vw,2.5rem);line-height:1.15}
article.learn h2{margin-top:30px}
.diag{display:grid;grid-template-columns:repeat(auto-fill,minmax(250px,1fr));gap:18px;margin:16px 0}
.diag figure{margin:0;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:12px}
.diag figcaption{font-size:.9rem;color:var(--muted);margin-top:8px}
.mini{display:grid;grid-template-columns:repeat(8,1fr);aspect-ratio:1;border-radius:4px;overflow:hidden}
.mini div{position:relative;background:var(--sq-light)}.mini div.d{background:var(--sq-dark)}
.mini img{position:absolute;inset:0;width:100%;height:100%}
.pill{display:inline-block;background:var(--accent-soft);color:var(--text);border-radius:999px;padding:2px 10px;font-size:.82rem;font-weight:600}
.tabs{display:flex;gap:6px;flex-wrap:wrap}
.tabs .btn[aria-pressed="true"]{background:var(--accent);color:var(--accent-ink);border-color:var(--accent)}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}