Doc: User tests of cat17 skin

The supporters list (accessed through the menu) is not displayed correctly. Partly left and top big margins appear. In addition, the text of the donation comments is partially cut off to the right, I can not scroll on the page to read the missing part.

Device: Moto G
Browser: Firefox
Browser version: 57.0.1
Viewport-size: 360 x 511
Screen width: 1024
Screen height: 768