Jerky behavior

Hi,

I use the latest version of Safari 8.0.8 a MacBook Pro 12″ 2015. I use Divi Theme from Elegant Themes version 2.5.3 with WordPress 2.3.1

If you look carefully when browsing to all my web pages : https://francoiscarrier.com there is a jump (jerky) reaction beneath the heater of each pages of my site. The pages move about 1 inches every time one gets onto any of the pages of my site.

I uploaded this short video to show what I mean:
https://www.dropbox.com/s/s2uo1xiefq84d … 2.mp4?dl=0

Notice when triggering or refreshing my welcome page the header jump (jerky) gap.

Then on the other 2 pages the first row gets stock under the header, and so on.

Please tell me what to do about this issue?

Thanks

FC
francoiscarrier.com