That’s because you have them set to auto. Set height and width and you’ll be good to go.
If by “responsive” you mean that they get bigger and smaller as you resize the screen, use vw for the image width and set the height as auto and do this with the column flexbox settings.
Thank you Cricitem, I managed to set the image to the same size that I want. However how do I remove all those padding/spaces between the bottom 2 images and close them up with the top 3 images as shown here : Image 2017-07-11 at 10.56.4...