* { margin:0; padding:0; box-sizing:border-box; }
body {
  background:#111;
  display:grid;
  place-items:center;
  height:100vh;
  color:#fff;
  font-family:monospace;
}
.ui {
  position:fixed; top:10px; left:10px;
  z-index:999;
}
.panel {
  background:#222;
  padding:8px 12px;
  border-radius:6px;
  cursor:pointer;
}
.content {
  background:#222;
  margin-top:4px;
  padding:8px;
  border-radius:6px;
  display:none;
}
.content.show { display:block; }
#canvas {
  border:2px solid #4af;
  background:#222;
}
#debug {
  position:fixed; top:10px; right:10px;
  background:#0006; padding:8px; border-radius:6px;
}
#loadBtn {
  background:#4af;
  border:none;
  padding:4px 8px;
  border-radius:4px;
  cursor:pointer;
}