:root{
  --bg0:#0b0b17;
  --felt0:#062814;
  --felt1:#0a3a20;
  --felt2:#052015;
  --text:rgba(245,245,255,.96);
  --muted:rgba(245,245,255,.70);
  --stroke:rgba(255,255,255,.14);

  --board-size:min(92vw, 560px);
  --sq:calc(var(--board-size) / 8);

  --warm:#ff4a43;
  --warm2:#ff8a2d;
  --cool:#28e1c6;
  --cool2:#3b75ff;

  --shadow:0 18px 60px rgba(0,0,0,.45);
}

*{box-sizing:border-box}
html,body{height:auto; min-height:100%}
html,body{max-width:100%; overflow-x:hidden}
body{
  margin:0;
  font-family: "Space Grotesk", ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color:var(--text);
  background:
    radial-gradient(900px 520px at 18% 15%, rgba(124,92,255,.22), transparent 60%),
    radial-gradient(820px 520px at 82% 14%, rgba(41,242,212,.18), transparent 58%),
    radial-gradient(900px 620px at 55% 95%, rgba(255,60,155,.16), transparent 60%),
    radial-gradient(900px 620px at 50% 120%, rgba(0,0,0,.40), transparent 70%),
    linear-gradient(180deg, var(--bg0), #05050d 60%, #070615);
}

.checkers-game{
  min-height:100svh;
  padding-bottom:max(32px, env(safe-area-inset-bottom));
}

.topbar{
  position:sticky;
  top:0;
  z-index:20;
  display:flex;
  gap:10px;
  align-items:center;
  justify-content:space-between;
  padding:14px 14px;
  background:
    radial-gradient(900px 520px at 20% -40%, rgba(41,242,212,.14), transparent 60%),
    radial-gradient(900px 520px at 80% -40%, rgba(124,92,255,.12), transparent 60%),
    rgba(8,8,16,.92);
  border-bottom:1px solid rgba(255,255,255,.12);
  box-shadow: 0 14px 60px rgba(0,0,0,.35);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}
.back-link{
  color:rgba(245,245,255,.88);
  text-decoration:none;
  font-weight:850;
  border:1px solid rgba(255,255,255,.12);
  background:rgba(255,255,255,.04);
  padding:8px 10px;
  border-radius:999px;
  white-space:nowrap;
}
.back-link:hover{border-color:rgba(41,242,212,.35); background:rgba(41,242,212,.06); transform:translateY(-1px)}
.title-wrap{min-width:0; display:flex; flex-direction:column; gap:2px; align-items:flex-start}
.title{
  margin:0;
  font-size:15px;
  letter-spacing:.5px;
  text-transform:uppercase;
  font-weight:950;
}
.status-line{font-size:12px; color:var(--muted); font-weight:800; white-space:nowrap; overflow:hidden; text-overflow:ellipsis; max-width:44vw}
.top-actions{display:flex; gap:8px; align-items:center}

.btn{
  border:1px solid rgba(255,255,255,.12);
  background:rgba(255,255,255,.04);
  color:rgba(245,245,255,.92);
  padding:10px 12px;
  border-radius:999px;
  font-weight:900;
  cursor:pointer;
  box-shadow: 0 18px 70px rgba(0,0,0,.18);
  transition: transform .15s ease, border-color .15s ease, background .15s ease, box-shadow .15s ease;
}
.btn:hover{
  transform:translateY(-1px);
  border-color:rgba(124,92,255,.35);
  background:rgba(124,92,255,.08);
  box-shadow: 0 26px 90px rgba(0,0,0,.30);
}
.btn:active{transform:translateY(0px) scale(.99)}
.btn.primary{
  background:linear-gradient(135deg, rgba(41,242,212,.22), rgba(124,92,255,.22));
  border-color:rgba(255,255,255,.18);
  box-shadow:0 14px 38px rgba(41,242,212,.10);
}
.btn.ghost{background:rgba(255,255,255,.02)}
.btn.big{min-height:44px; padding:12px 16px; font-size:14px}
.btn[disabled]{opacity:.6; cursor:not-allowed}

.layout{
  width:min(1200px, 100%);
  margin:0 auto;
  padding:14px 12px 22px;
  display:grid;
  grid-template-columns: 280px 1fr;
  gap:14px;
  align-items:start;
}

.hud{display:flex; flex-direction:column; gap:12px}
.hud-card{
  border:1px solid rgba(255,255,255,.12);
  background:linear-gradient(180deg, rgba(18,16,35,.78), rgba(10,9,16,.72));
  border-radius:18px;
  padding:12px;
  box-shadow: var(--shadow);
}
.hud-row{display:flex; align-items:center; justify-content:space-between; gap:10px; padding:7px 2px}
.hud-row .k{font-weight:950; letter-spacing:.2px; font-size:12px; color:rgba(245,245,255,.70); text-transform:uppercase}
.hud-row .k.warm{color:rgba(255,138,61,.92)}
.hud-row .k.cool{color:rgba(41,242,212,.92)}
.hud-row .v{font-weight:950; font-variant-numeric: tabular-nums}
.chip{
  border:1px solid rgba(255,255,255,.14);
  background:rgba(255,255,255,.04);
  padding:6px 10px;
  border-radius:999px;
}
.controls{display:flex; flex-direction:column; gap:10px}

.board-wrap{
  display:flex;
  flex-direction:column;
  align-items:center;
  gap:10px;
}

.board{
  width:var(--board-size);
  height:var(--board-size);
  border-radius:22px;
  border:1px solid rgba(255,255,255,.12);
  background:
    radial-gradient(120% 120% at 15% 10%, rgba(255,255,255,.10), transparent 52%),
    radial-gradient(140% 140% at 80% 110%, rgba(0,0,0,.35), transparent 55%),
    linear-gradient(180deg, rgba(10,60,34,.92), rgba(6,30,18,.92));
  box-shadow:0 30px 90px rgba(0,0,0,.55);
  padding:10px;
  display:grid;
  place-items:center;
}

.grid{
  width:calc(var(--board-size) - 20px);
  height:calc(var(--board-size) - 20px);
  display:grid;
  grid-template-columns:repeat(8, 1fr);
  grid-template-rows:repeat(8, 1fr);
  border-radius:16px;
  overflow:hidden;
  border:1px solid rgba(255,255,255,.08);
}

.sq{
  position:relative;
  border:0;
  padding:0;
  display:grid;
  place-items:center;
  cursor:pointer;
  user-select:none;
  -webkit-tap-highlight-color: transparent;
}
.sq.light{
  background:
    radial-gradient(120% 120% at 20% 20%, rgba(255,255,255,.22), transparent 55%),
    linear-gradient(180deg, rgba(255,255,255,.08), rgba(0,0,0,.03));
}
.sq.dark{
  background:
    radial-gradient(120% 120% at 20% 10%, rgba(255,255,255,.12), transparent 55%),
    linear-gradient(180deg, rgba(20,16,40,.86), rgba(8,6,16,.86));
}
.sq.dark:hover{outline:2px solid rgba(255,255,255,.06); outline-offset:-2px}
.sq[disabled]{cursor:default}

.sq.valid{
  outline:3px solid rgba(41,242,212,.72);
  outline-offset:-3px;
}
.sq.capture{
  outline:3px solid rgba(255,138,61,.78);
  outline-offset:-3px;
}
.sq.valid::after{
  content:"";
  width:14px; height:14px;
  border-radius:50%;
  background:rgba(41,242,212,.85);
  box-shadow:0 0 0 6px rgba(41,242,212,.12);
}
.sq.capture::after{
  content:"";
  width:14px; height:14px;
  border-radius:50%;
  background:rgba(255,138,61,.92);
  box-shadow:0 0 0 6px rgba(255,138,61,.14);
}

.piece{
  width:calc(var(--sq) * .84);
  height:calc(var(--sq) * .84);
  border-radius:999px;
  position:relative;
  display:grid;
  place-items:center;
  box-shadow:
    0 10px 24px rgba(0,0,0,.45),
    inset 0 8px 18px rgba(255,255,255,.14),
    inset 0 -12px 18px rgba(0,0,0,.22);
  transform: translateZ(0);
  transition: transform .14s ease, filter .14s ease;
}
.piece.warm{
  background:
    radial-gradient(70% 70% at 28% 22%, rgba(255,255,255,.40), transparent 55%),
    radial-gradient(90% 90% at 70% 85%, rgba(0,0,0,.28), transparent 60%),
    linear-gradient(180deg, var(--warm2), var(--warm));
}
.piece.cool{
  background:
    radial-gradient(70% 70% at 28% 22%, rgba(255,255,255,.38), transparent 55%),
    radial-gradient(90% 90% at 70% 85%, rgba(0,0,0,.26), transparent 60%),
    linear-gradient(180deg, var(--cool), var(--cool2));
}
.piece.selected{
  transform: translateY(-3px) scale(1.02);
  filter: drop-shadow(0 10px 18px rgba(255,255,255,.10));
}

.face{
  width:78%;
  height:78%;
  border-radius:999px;
  background:
    radial-gradient(120% 120% at 35% 18%, rgba(255,255,255,.40), rgba(255,255,255,.10) 50%, rgba(0,0,0,0) 76%),
    linear-gradient(180deg, rgba(255,255,255,.10), rgba(255,255,255,.05));
  border:1px solid rgba(255,255,255,.16);
  display:grid;
  place-items:center;
  position:relative;
  box-shadow:
    inset 0 8px 18px rgba(255,255,255,.10),
    inset 0 -10px 16px rgba(0,0,0,.18);
}
.eyes{
  position:absolute;
  inset:0;
  pointer-events:none;
}
.eye{
  position:absolute;
  width:19%;
  height:24%;
  top:31%;
  border-radius:999px;
  background: radial-gradient(120% 120% at 35% 30%, #ffffff 0 32%, #dfe8ff 60%, #c9d8ff 100%);
  border:1px solid rgba(0,0,0,.14);
  overflow:hidden;
  box-shadow:
    0 2px 0 rgba(255,255,255,.80) inset,
    0 -2px 0 rgba(0,0,0,.10) inset,
    0 10px 18px rgba(0,0,0,.16);
}
.eye:first-child{left:32%}
.eye:last-child{right:32%}
.eye::after{
  content:"";
  position:absolute;
  width:18%;
  height:18%;
  border-radius:999px;
  left:44%;
  top:22%;
  background:rgba(255,255,255,.92);
}

.pupil{
  position:absolute;
  width:46%;
  height:46%;
  border-radius:999px;
  left:30%;
  top:40%;
  background: radial-gradient(120% 120% at 35% 30%, #4a2b43 0, #111 60%, #000 100%);
  box-shadow: 0 2px 0 rgba(255,255,255,.18) inset;
}
.brow{
  position:absolute;
  top:-14%;
  width:24%;
  height:12%;
  border-radius:999px;
  background: rgba(0,0,0,.18);
  transform: rotate(-12deg);
}
.brow.b2{transform: rotate(12deg)}
.cheeks{
  position:absolute;
  left:50%;
  bottom:26%;
  transform: translateX(-50%);
  width:84%;
  display:flex;
  justify-content:space-between;
  pointer-events:none;
}
.cheek{
  width:16%;
  height:12%;
  border-radius:999px;
  background:
    radial-gradient(120% 120% at 50% 50%, rgba(255,255,255,.35), rgba(255,255,255,0) 55%),
    radial-gradient(120% 120% at 50% 50%, rgba(255,120,185,.55), rgba(255,120,185,0) 70%);
  opacity:.85;
}
.piece.warm .cheek{
  background:
    radial-gradient(120% 120% at 50% 50%, rgba(255,255,255,.35), rgba(255,255,255,0) 55%),
    radial-gradient(120% 120% at 50% 50%, rgba(255,120,185,.55), rgba(255,120,185,0) 70%);
}
.piece.cool .cheek{
  background:
    radial-gradient(120% 120% at 50% 50%, rgba(255,255,255,.35), rgba(255,255,255,0) 55%),
    radial-gradient(120% 120% at 50% 50%, rgba(120,220,255,.40), rgba(120,220,255,0) 70%);
}
.mouth{
  position:absolute;
  top:57%;
  left:50%;
  width:24%;
  height:18%;
  transform:translateX(-50%);
  border-radius:0 0 999px 999px;
  background:
    radial-gradient(130% 120% at 50% 15%, rgba(255,255,255,.35), rgba(255,255,255,0) 55%),
    linear-gradient(180deg, #1a0b17, #000);
  box-shadow: 0 2px 0 rgba(255,255,255,.15) inset;
  opacity:.9;
}
.mouth::after{
  content:"";
  position:absolute;
  left:50%;
  bottom:8%;
  width:62%;
  height:46%;
  transform: translateX(-50%);
  border-radius:999px;
  background: radial-gradient(120% 120% at 35% 30%, rgba(255,180,210,.92), rgba(255,80,160,.88));
  opacity:.95;
}

.king{
  position:absolute;
  top:-10%;
  width:70%;
  height:34%;
  border-radius:14px 14px 18px 18px;
  background:linear-gradient(180deg, #ffe28a, #b57b1d);
  border:1px solid rgba(255,255,255,.35);
  box-shadow: 0 10px 18px rgba(0,0,0,.35);
  display:grid;
  place-items:center;
}
.king::before{
  content:"♛";
  font-size:18px;
  color:rgba(60,35,10,.95);
  filter: drop-shadow(0 2px 0 rgba(255,255,255,.35));
}
.piece.kinged{animation: kingPop .55s ease}
@keyframes kingPop{
  0%{transform: translateY(0) scale(1)}
  40%{transform: translateY(-8px) scale(1.10)}
  70%{transform: translateY(-3px) scale(1.05)}
  100%{transform: translateY(0) scale(1)}
}
.piece.captured{animation: poof .22s ease forwards}
@keyframes poof{
  to{transform: scale(.3) rotate(10deg); opacity:0}
}

.move-hint{
  width:min(92vw, 560px);
  min-height:22px;
  text-align:center;
  color:rgba(245,245,255,.78);
  font-weight:850;
  font-size:13px;
}

.stats{
  width:min(92vw, 560px);
  border-radius:18px;
  border:1px solid rgba(255,255,255,.12);
  background:linear-gradient(135deg, rgba(255,255,255,.03), rgba(255,255,255,.01));
  box-shadow: var(--shadow);
  padding:12px;
}
.stats-title{font-weight:1000; letter-spacing:.25px; text-transform:uppercase; font-size:13px; color:rgba(245,245,255,.86); margin:0 0 10px}
.stats-grid{
  display:grid;
  grid-template-columns:repeat(2, minmax(0, 1fr));
  gap:8px 10px;
}
.stat{
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:10px;
  padding:8px 10px;
  border-radius:14px;
  border:1px solid rgba(255,255,255,.10);
  background:rgba(255,255,255,.02);
}

.overlay{
  position:fixed;
  inset:0;
  z-index:1000;
  display:grid;
  place-items:center;
  padding:18px;
  background: rgba(4,4,12,.55);
}
.overlay[hidden]{display:none !important}
.panel{
  width:min(92vw, 520px);
  border-radius:22px;
  border:1px solid rgba(255,255,255,.16);
  background:linear-gradient(180deg, rgba(18,16,35,.94), rgba(10,9,16,.92));
  box-shadow:0 30px 120px rgba(0,0,0,.65);
  padding:16px;
}
.panel-head{display:flex; flex-direction:column; gap:6px; margin-bottom:12px}
.panel-title{font-weight:1000; letter-spacing:.25px; font-size:18px}
.panel-sub{color:rgba(245,245,255,.74); font-weight:850; font-size:13px}
.panel-section{margin:14px 0}
.label{font-weight:950; letter-spacing:.2px; text-transform:uppercase; font-size:12px; color:rgba(245,245,255,.68); margin-bottom:8px}
.seg{display:flex; flex-wrap:wrap; gap:10px}
.seg-btn{
  flex:1 1 auto;
  min-height:40px;
  padding:10px 12px;
  border-radius:999px;
  border:1px solid rgba(255,255,255,.14);
  background:rgba(255,255,255,.03);
  color:rgba(245,245,255,.88);
  font-weight:950;
  cursor:pointer;
}
.seg-btn.active{
  background:linear-gradient(135deg, rgba(41,242,212,.22), rgba(124,92,255,.22));
  border-color:rgba(255,255,255,.20);
}
.opt-row{display:flex; gap:14px; flex-wrap:wrap}
.opt{display:flex; gap:10px; align-items:center; font-weight:900; color:rgba(245,245,255,.88)}
.opt input{accent-color: rgba(41,242,212,.9)}
.panel-actions{display:flex; justify-content:flex-end; margin-top:10px}

.drawer-panel{
  position:fixed;
  left:50%;
  top:max(12px, env(safe-area-inset-top));
  bottom:max(12px, env(safe-area-inset-bottom));
  transform:translateX(-50%);
  width:min(94vw, 760px);
  overflow:hidden;
  display:flex;
  flex-direction:column;
  z-index:1100;
  border-radius:22px;
  background:rgba(8, 45, 28, 0.98);
  border:1px solid rgba(255,255,255,0.18);
  box-shadow:0 24px 80px rgba(0,0,0,0.55);
}
.drawer-panel[hidden]{display:none !important}
.drawer-header{
  flex:0 0 auto;
  display:flex;
  justify-content:space-between;
  align-items:center;
  gap:10px;
  padding:14px 16px 10px;
  border-bottom:1px solid rgba(255,255,255,0.14);
}
.drawer-header h2{margin:0; font-size:16px; font-weight:1000; letter-spacing:.2px}
.drawer-body{
  flex:1 1 auto;
  min-height:0;
  overflow-y:auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
  padding:10px 16px 18px;
}
.drawer-footer{
  flex:0 0 auto;
  padding:10px 16px max(14px, env(safe-area-inset-bottom));
  border-top:1px solid rgba(255,255,255,0.14);
  background:rgba(8, 45, 28, 0.98);
}
.drawer-lead{color:rgba(245,245,255,.86); font-weight:850; line-height:1.35}

/* Guide styling (matches Chess) */
.guide{scroll-behavior:smooth}
.toc{
  margin-top:12px;
  border:1px solid rgba(255,255,255,0.14);
  background:rgba(255,255,255,0.04);
  border-radius:18px;
  padding:12px;
  position:sticky;
  top:0;
  z-index:3;
}
.toc-title{font-weight:1000; letter-spacing:.2px; margin-bottom:8px}
.toc-grid{display:grid; grid-template-columns:repeat(2, minmax(0,1fr)); gap:6px}
.toc a{
  color:rgba(245,245,255,.90);
  text-decoration:none;
  font-weight:850;
  font-size:13px;
  padding:8px 10px;
  border-radius:14px;
  border:1px solid rgba(255,255,255,.10);
  background:rgba(0,0,0,.18);
}
.toc a:hover{border-color:rgba(124,92,255,.35)}
.gsec{padding-top:10px; margin-top:8px}
.gsec h3{margin:12px 0 8px; font-size:16px}
.cards{display:grid; grid-template-columns:repeat(2, minmax(0,1fr)); gap:10px}
.card{
  border:1px solid rgba(255,255,255,0.14);
  background:rgba(255,255,255,0.04);
  border-radius:16px;
  padding:10px;
}
.card .h{font-weight:1000}
.card .b{color:rgba(245,245,255,.78); font-weight:850; margin-top:4px; font-size:13px; line-height:1.25}
.callout{
  margin-top:10px;
  border-radius:18px;
  padding:10px 12px;
  border:1px solid rgba(255,255,255,0.14);
  background:rgba(0,0,0,.20);
}
.callout .t{font-weight:1000; letter-spacing:.2px}
.callout.tip{border-color:rgba(41,242,212,.28); background:rgba(41,242,212,.08)}
.callout.warn{border-color:rgba(255,138,61,.28); background:rgba(255,138,61,.08)}
.toplink{
  display:inline-block;
  margin-top:10px;
  color:rgba(245,245,255,.82);
  font-weight:900;
  text-decoration:none;
  border:1px solid rgba(255,255,255,0.12);
  background:rgba(255,255,255,0.03);
  padding:8px 10px;
  border-radius:999px;
}
.ref{
  display:grid;
  gap:8px;
  border:1px solid rgba(255,255,255,0.14);
  background:rgba(255,255,255,0.04);
  border-radius:16px;
  padding:12px;
  font-weight:850;
  color:rgba(245,245,255,.82);
}

body.modal-open{overflow:hidden}

@media (max-width: 980px){
  .layout{grid-template-columns: 1fr; justify-items:center}
  .hud{width:min(92vw, 560px)}
  .status-line{max-width:55vw}
}
@media (max-width: 520px){
  :root{ --board-size: min(94vw, 420px); }
  .top-actions .btn{padding:9px 10px}
}
@media (max-height: 620px){
  .drawer-panel{
    top:max(6px, env(safe-area-inset-top));
    bottom:max(6px, env(safe-area-inset-bottom));
    border-radius:16px;
  }
  .drawer-header{padding:10px 12px 8px}
  .drawer-body{padding:8px 12px 12px}
  .drawer-footer{padding:8px 12px max(10px, env(safe-area-inset-bottom))}
  .drawer-header h2{font-size:15px}
}

@media (max-width: 720px){
  .toc-grid{grid-template-columns:1fr}
  .cards{grid-template-columns:1fr}
}