Hey @Arnaudfrenchy,
the thing is that you're using a method that is outdated and it won't work for responsive or screens that are smaller than the image you're using. The coordinates for each region are calculated based on the initial image size so if you have an image that is for example 800x600 then all coordinates will be generated based on this size and when you resize the screen the values will remain the same even if the image resizes. A solution will be to use an SVG image which will work on any screen size.
Cheers,
Max.