Hi,
The small_pic_size is the max width and heigth of a picture.
if you set $use_small_pic_size_as_height to true (=default)
it's only the height and everything has the height of small_pic_size but the width is only restricted by $maxXSize. But $maxXSize is actually intende only to work for paronama images - therefor a width/height ratio of 1.5 is needed for a picture ..
Mybe you try to set $use_small_pic_size_as_height to false !
In your layout I think bottom navigation should be turned off.
you should also remove the folder.txt and folder_de.txt from the main folder - This is intended for additional text (the german text is shown right now for me).
Is there a reason why your layout is only 600px high? You don't give the gallery much space
/Michael