Align 'Read More' buttons in Summary Block

[update - I have managed to get it working (hooray) but for some reason, the thumbnail gets hidden... I have no idea why.]

I'm trying to align all the "Read More" buttons/links in a summary bloack to sit at the bottom of the block. I've managed to use flex-box to make the summary blocks all the same size (why this isn't a feature by default I have no idea), and I'm trying to do something similar for the read more buttons but I can't get it to work.

I think the below code is somewhat correct, but I can't figure out how to get it working. 

  display: flex;
  flex: 1;
  flex-direction: column;
  justify-content: space-between;

@beatrizc, I was following one of your blog posts about it, but I can't seem to get it working, perhaps you're able to help?

Can you share link to page where you use summary block?

Did you get anywhere with this? I'm looking for the same fix.

any update on this

For future comments, this can be solved with some CSS code. If you need to fix, please share link to page where you use summary block, we can check & help easier