1. A method of rendering media for use with selected products, comprising: providing a user interface for use in designing theme designs, wherein each theme design includes: a workspace having a print area, and an arrangement of graphic elements, wherein each of the graphic elements in the arrangement is associated with: a desired size of that graphic element relative to or the print area, and a rendering parameter that determines an appearance of that graphic element within the workspace or print area; receiving an indication of a selected theme design, a selected product having the print area, and one or more images to be used with the selected product; receiving an indication of an adjustment to the height and width of the print area from an initial aspect ratio to a resized aspect ratio; rendering media for use with the selected product, including: determining a minimum value equal to a lesser of the adjusted height or adjusted width of the resized print area, adjusting the size and appearance of each of the graphic elements in the selected theme design to maintain its desired size relative to that of the print area and its aspect ratio independent of an aspect ratio of the resized print area by multiplying each of the height and width of the graphic element by the minimum value, displaying each graphic element by applying its rendering parameters to fit the resized aspect ratio; and displaying a preview of the selected product together with its print area including the one or more images and the graphic elements of the selected theme design as adjusted.