Jouy Theme has all fonts included within the theme except for the header banner font which is actually an extra created .png file image.
You can find the header banner font Audrey & Louis here: https://bit.ly/2LK2Xp3
Body font is called Quattrocento Sans
We recommend to upload post images with a width of at least 770px. Optimal images sizes should not exceed a width of 1200px.