Hello @dsonesuk,
thank you for your answer! 🌷
Hmmh. It really has to look like my first CodePen example, only without the gap.
I tried to use your code. The result shows the same problem: https://www.w3schools.com/code/tryit.asp?filename=G4GRV9BNJM2D
Here are also gaps between the images.
Best,
lenato