use 'width' and 'height' URL parameters to change both, there is a recursion limit :)
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | | | | | + + +--+--+--+ +--+ + +--+ +--+ +--+--+ + | | | | | | | | | | | + +--+ +--+ + + +--+--+ +--+ +--+ + +--+ | | | | | | | | | +--+ + +--+ + +--+--+ + + +--+--+ +--+ + | | | | | | | | | | | + +--+ + + +--+--+ + + + + + + + +--+ | | | | | | | | | | | | + + + + +--+ +--+--+ +--+--+ + + +--+ + | | | | | | | | | | + +--+--+--+ + + + +--+--+--+--+ +--+--+ + | | | | | | | | | | + + + +--+--+--+ + + + +--+ +--+ +--+ + | | | | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+