:root{
  --bg:#0e1014;
  --panel:#161a22;
  --grid:#2a3142;
  --text:#e6e9f0;
  --muted:#9aa3b5;
  --accent:#6bdcff;
}
*{box-sizing:border-box;}
html,body{height:100%;}
body{
  margin:0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
  background:var(--bg);
  color:var(--text);
}
header{
  display:flex;
  justify-content:space-between;
  align-items:flex-end;
  gap:12px;
  padding:14px 14px 8px;
}
.title{font-size:22px;font-weight:700;letter-spacing:0.6px;}
.meta{display:flex;gap:12px;flex-wrap:wrap;justify-content:flex-end;align-items:center;}
.label{color:var(--muted);font-size:12px;margin-right:6px;}

.sfx{
  border: 1px solid rgba(255,255,255,0.12);
  background: rgba(107,220,255,0.08);
  color: var(--text);
  padding: 8px 10px;
  border-radius: 12px;
  font-weight: 750;
  display: inline-flex;
  gap: 8px;
  align-items: center;
}
.sfx[aria-pressed="false"]{
  opacity: 0.6;
  background: rgba(255,255,255,0.05);
}
.sfxLabel{color: var(--muted); font-size: 12px; font-weight: 800;}
.sfxState{font-size: 12px; font-weight: 900;}
main{padding:0 14px 14px;}

.boardWrap{display:flex;gap:12px;align-items:flex-start;justify-content:center;}
#game{
  background:var(--panel);
  border-radius:12px;
  box-shadow: 0 0 0 1px rgba(255,255,255,0.06) inset;
  touch-action:none; /* prevent scroll while playing */
}
.side{width:160px;display:flex;flex-direction:column;gap:10px;}
.panel{
  background:var(--panel);
  border-radius:12px;
  padding:10px;
  box-shadow: 0 0 0 1px rgba(255,255,255,0.06) inset;
}
.panelTitle{color:var(--muted);font-size:12px;margin-bottom:8px;}
#next,#hold{background:transparent;display:block;margin:0 auto;}
.hintLine{color:var(--muted);font-size:12px;line-height:1.35;}

.controls{
  display:grid;
  grid-template-columns: repeat(4, minmax(0,1fr));
  gap:10px;
  margin:14px auto 0;
  max-width:520px;
}
.btn{
  border:0;
  background:#22283a;
  color:var(--text);
  padding:14px 12px;
  border-radius:14px;
  font-size:16px;
  font-weight:650;
  box-shadow: 0 6px 18px rgba(0,0,0,0.35);
  user-select:none;
  -webkit-user-select:none;
  touch-action:manipulation;
}
.btn:active{transform: translateY(1px); background:#2b3350;}

.kbd{margin:12px auto 0;max-width:520px;color:var(--muted);}
.kbd summary{cursor:pointer;}
.kbdGrid{margin-top:8px;display:grid;grid-template-columns: 1fr 1fr;gap:6px 14px;font-size:13px;}

.overlay{
  position:fixed; inset:0;
  background: rgba(0,0,0,0.55);
  display:flex;
  align-items:center;
  justify-content:center;
  padding:18px;
}
.hidden{display:none;}
.overlayCard{
  width:min(520px, 100%);
  background: #121520;
  border-radius:16px;
  padding:16px;
  box-shadow: 0 24px 60px rgba(0,0,0,0.6);
  border: 1px solid rgba(255,255,255,0.08);
}
.overlayTitle{font-size:20px;font-weight:800;margin-bottom:6px;}
.overlayMsg{color:var(--muted);font-size:14px;margin-bottom:12px;}
.overlayBtns{display:flex;gap:10px;justify-content:flex-end;}

@media (max-width: 620px){
  .boardWrap{flex-direction:column;align-items:center;}
  .side{width:min(520px,100%);flex-direction:row;flex-wrap:wrap;justify-content:center;}
  .panel{width:160px;}
}