Easy to create, easy to edit and you don't even need a graphics editor to get nice pictures.
FEN positions can be copy/pasted from the chess software or just typed in manually. Basically it just takes a few seconds to describe the board position using Forsyth Edwards notation.
Use <img> tag to append your FEN position to the http://www.fen-to-image.com/image/ and put it anywhere on your web-site. A nice diagram will appear. The default image is full bleed (filling to the edges).
Single and double borders, with or without the coordinates could be shown along the left and lower edges (check the manual).