freego_api/ui/styles/board.module.css

.gridContainer {
  display: grid;
}

.gridCell {
  border: 1px solid black;
  padding-top: 100%; /* 100% is supposed to be 1:1 aspect ratio but it doesn't look like it */ 
  background: 0;
}

.cellClicked {
  border: 1px solid red;
}