Hover effect problem on navbar

Hi there,
I want to make a hover effect on a navigation bar.
The problem is that the effect only applies to one item, and not to the others, because of the superimposition of the effect on the rest of the menu items.
I made a video capture, you will understand : https://www.dropbox.com/s/nxifhx4ykox4z6v/116000-webdesign.mp4?dl=0

How to solve this problem and get the effect on each item?

Thanks for your help !