I have had a look at your video under the documentation section for CGC about how to customize the look of the card. I have created a background image which includes the "text area" and removed the "boite_50.jpeg" file from the "floatbox" parameter. I have also applied a number of other changes such as fonts, colours and positioning etc. however when I uploaded the edited "default.xml" file and tested the component in the front end, when I clicked "preview" the window was blank. I then had another look at your tutorial and noticed that you said something about changing the xml file to "card_template". I then changed the filename to "card_template.xml" and tried again, but that did not work either.
Please advise me on the issue ASAP.