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?
Best Answer
They should be given the same max height, i.e. they should be the same length if they would otherwise go off the board. If not, it's a bug.
There's a known bug that you may be experiencing. If you are zoomed out and click the 'Add card', then click off, it can shorten the list.
Most of this weirdness will go away with the new card composer, though. https://trello.com/c/pRlmLRWS