Widget to set the formatting of the different fields in a card

At the top of the widget, you should be able to choose which card type you want to change, or change the properties of all cards simultaneously. Then, the widget should allow to change font, colour and alignment for each of the fields in the card type, as well as change the card background colour. It would be nice if the right hand part of the widget contained a preview of a sample card.

The results should be converted into a css file, which is saved inside .mnemosyne/css