Where can I change or add the hr tag in the social theme css

Hi, I have the social theme installed, when i add the hr tag in the HTML editor in the add post/page section the the hr shows up in the visual mode but when I publish page they is nothing there. Do I need to add the hr tag in the css of the theme if so where do I need to add it and which file? I know its definitely the theme making the hr tag not to show as i have tried it using another theme and it worked ok, I have also disabled all plugins and it still does not work.
my website address is http://memoriesforeternity.org