CSS grids: align square cells with container edges with consistent grid gap?

Question

The goal is to align square cells with their container\'s leading and trailing edges while achieving a consistent gap between cells on each row, and between each row.

<

Answer 1

The issue is that the grid cells are fine but the content inside (li) is not matching them.

Instead of using fixed width/height on the li you can consider percentage value and they will be a bit bigger in some cases but will remain square elements:

ul {
  display: grid;
  width: 260px;
  grid-template-columns: repeat(auto-fit, minmax(40px, 1fr));
  grid-auto-rows: 1fr;
  grid-gap: 10px;
  list-style-type: none;
  border: 2px solid black;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  background: gray;
  animation:change 5s linear alternate infinite;
}

li {
  width: 100%;
  padding-top:100%;
}

@keyframes change {
  to {width:120px}
}