Custom Main Menu Hover

Hello WP-community,
I am currently struggling with customizing a hover block for my website.
You can view it here: http://www.epicollab.com

I saw this feature on another website – and I am trying to come pretty close to it: http://http://www.rappfrance.com/

I would like for an orange block to hover the main menu nav.
I have been successful in getting it to appear, but it is not aligned properly. If and when you visit the URL I provided, you will see the hover-color block on my website (epicollab) extends downward.

Any code adjustments/suggestions/ideas greatly appreciated.
Cheers!