Q:

Blank space right side screen on small device or window

I've a problem on my site, there is some blank space which appear when I resize the window under width:450px, and the space grow the smaller is the window. It's really a problem on some mobile. However I need to scroll to the right to see the space on firefox or chrome, on pc. The worst is, there is no space with the native browser of my phone... (android).
The website: start-track.fr
It's in French but we all speak the same language, HTML and CSS. :)
The code is quiet big so I will edit it if it really helps.
EDIT:
Screenshot:

A:

Change the width in your media stylesheet:

@media screen and (max-width: 550px)
#copy {
    height: 12%;
    bottom: 10px;
    width: 178px;
    left: calc(50% - 75px);
}

