Upload Image With a Hidden Fille Upload Widget

Hi,

I need feature to work on mobile phone for uploading images in File Repository, however, I want to replace the file upload widget with a single button to choose the image.

For example:

Instead of showing this:

Show something like this:

When I click the button marked as red I can choose te image that will replace the grey area.

The reason why I want to do this is because the File Upload widget is a little big and I can't set any style.

If there's any other file upload widget, please, recommend me.

Thanks in advance.