Hr is appearing differently on pages

Ok, this is a bit strange. I am working with a Wordpress theme for the first time (Responsive Theme). On the pages I insert the <hr> code. The first <hr> on the page is quite bold and darker looking. All subsequent <hr>'s on the page are lighter. It doesn’t look very uniform. Any idea why this is happening? This is happening on my “Services” page and my “Projects” page. It also is happening in my “news” widget on the right side of the Services and Projects pages.

Any thoughts?

Seems to be related to the use of .1em as the height as defined in your style.css. When I change it to 2px, they all look uniform.

Wow, thank you. That did the trick. It was driving me nuts!