I gather FlowKit is for tree-shaped programs, without very many loops in them. I was able to figure this out by right clicking the leftmost image on the landing page's Examples section and opening it in a new tab. Then, it showed me enough of the two cells in the example for me to see that one was indented relative to the other.
I really think I should be able to tell that much from just looking at a screenshot on the landing page, without doing anything special.