Each theme consists of a single PNG image file. This image
consists of an array of seven rows, corresponding to the different
object colors/shapes, and four columns, each of which is a frame in the
animation of the object. The actual size of the image is irrelevant,
it will be rescaled, but the sub-images must form a four by seven
grid to get the correct effect. When using SVG remember that the
image size is the page size, if your grid does not fill the page
try shrinking the page size. Use an existing theme as a
guide.
