Comment seperation/styling tweaks

[arraypress]

Because there is no real separation between the parent and child comments via top or left hand borders, it can be tough reading longer commented threads and keeping track.

I feel a very minimal (but noticeable) bordered approach like the Easy Digital Downloads site has should be adopted in the parent Themedd since comments are a fundamental part of the site/theme:

https://easydigitaldownloads.com/blog/themedd-free-theme-easy-digital-downloads/