You seem to be using some custom css for the mobile version. You're hiding the text and you gave the image a class of "bureau" which also hides it. That's why you don't see anything
.bureau {
display: none;
}
.text {
display: none;
}
It seems that you only want to hide the text on the frontpage and not in contact for mobile. Then you need to target the frontpage's text:
body[data-type="category"][data-id="1"] .text {
display: none;
}
Please read the first few paragraphs here to learn about targeting certain Lay Theme pages with CSS:
http://laytheme.com/how-to-use.html#custom-css-styling
Anyway, if u just want the text to be smaller on mobile, please use textformats for that.
