Adding gray bars to separate content

Hello – When I staring using the theme I am using – Clearline – I added code to create gray bars to separate various sections of my index page and my posts. The bars are seen here:

http://www.goddesssophiawalker.com/wordpress/

Unfortunately now I can’t seem find where I edited my code to make this happen.

I am planning to switch to the Twenty Ten theme, can anyone suggest how I might add those bars to Twenty Ten?

Thank you very much!