Problem with width when there is only a few comments - resize the HR to fit the sidebar

Hi,

it seems when more than a few comments it is OK, but with only one or a couple then the HR goes right through the sidebar and so does the outline of the comments.

e.g

http://www.reddit.com/r/Apocalypse/comments/1c3c8c/far_from_dead_chapter_2/

(has only one or two comments)

vs

http://www.reddit.com/r/Apocalypse/comments/1c89ri/zombie_apocalypse_or_giant_spider_apocalypse/

( a few comment)

thanks for any help or advice