Experience this live demo on CodePen by visiting it here.
1) When you click on the grid, a first red point will be added.
2) Click on the grid again to add a second red point.
3) By clicking back on the first red point, you may notice that the coordinates do not update. This could be due to an overlay issue. Is there a solution for this? Just like in this example:
Take a look at the example here
.red-dot {
position: absolute;
width: 15px;
height: 15px;
background: red;
}