Themes are currently limited by the following constraints.
Should be designed in a 64 * 48 square.

This square is then divided into 9.
Each corner is 16 * 16 which will always be drawn with no transformations.

The top and bottom rows should be 32 * 16 and will be scaled on the X axis
depending on how wide the display is.

The left and right sides should be 16 * 16 and will be repeated as many times
on the Y axis as needed to fill the space.

The middle section that is left over should be 32 * 16 and will be scaled on
the X axis to fill the space, and repeated on the Y.
