Custom CSS

Dear sir/madam.

I am sorry to write this way, but I was unable to find answers on the forums. I have two issues that I am trying to solve.

1) I have a specified size of the grid item and I would like to customize the alignment of the picture. I can change the size, but I don't know how to center the picture. It is always fixed and I can manipulate only with the size. For example, see makemycitysmart.com, the first post.

2) I use the button Load more for makemycitysmart.com/journal, but I cannot adjust the button size. There is no native functionality for that.

Could you please help me?