Editing comment header?

How would I edit the comment header on my blog so that there is no bottom line?

https://www.simplygaming.info/2008/01/22/new-psn-ad-mocks-xbox-live-costs/#comment-899

Here is an example. I’m trying to get it so that the gravatar icons can fit in the header by getting rid of the bottom solid black line.

Thanks.

*Edit*

Looking at the style of this comment on www.remarpro.com, it would be even better if I could get the name and avatar to appear on the left side of the comment…