Here's a screenshot of two long lists on one of the Trello boards we use at Stack Exchange:
Both lists are fairly long - long enough to scroll. But one list "looks" longer than the other. What determines how long the gray container part of each list is? Why don't they just go down to the bottom of the window?
They aren't stretching or compressing to display the same number of full cards - the left list shows 8 full cards while the right list shows 9 full cards. They also aren't stretching or compressing to round up or down to the nearest "full card" - you can see a portion of a card at the bottom of each list. (Both of these lists are scrolled all the way to the top, although to my eyes it does look like the list on the right is scrolled down a tiny bit. This is an optical illusion of some kind - I double checked.)
So: what's the story here?