Minor Styling Help

Hi,
I have added the ‘related_posts();’ code to my single.php file where I want it but now there is no space between the bottom of the thumbnails and my Disqus stuff, could you let me know how to add some space between the two?

Also, I have centred the thumbnails by adding the recommended code to the bottom of my stylesheet, is there a way to add more space between each thumbnail so that they fill the width of my posts?

Thanks in advance for any help,
Ty
https://www.thefootdown.co.uk/

https://www.ads-software.com/plugins/yet-another-related-posts-plugin/