In the Upload File element, there is a square grey box with the text “Choose File” and a text “No file chosen” which is later replaced by the filename chosen.

Is there a way to control the look and feel of the parts of this element ? Font, text, and box colour ?

Yes there is.
You can add this to an html element on your form to see it working in form builder.

Can you be a bit more specific, Eric ?

This style should be used to control the look of the Upload File element, but where to put it ?

Thanks.

Thank you, Eric. Very helpful.