Some puzzles with large height have too much padding
Compare https://puzz.link/p?fillomino/1/682 and https://puzz.link/p?fillomino/1/683 - there is suddenly a lot of padding at the top and bottom at 683. (Would test more widths but puzz.link is no longer loading custom-sized boards for me).
Edit: see also, say https://puzz.link/p?fillomino/10/682 and https://puzz.link/p?fillomino/10/683, so 682/3 seems to be a constant.
Edit: It seems to disappear again at size 1024 https://puzz.link/p?fillomino/1/1024 (compare with https://puzz.link/p?fillomino/1/1023), and the padding seems to increase steadily as the grid size goes from 682 to 1023.
Strangely I can't reproduce this anymore with Firefox. I can't imagine I fixed it inadvertently... In Safari I still see this, and also on pzv.jp with Firefox. Which browser are you using?
Chrome 79.0.3945.79
There seems to be more involved here than the precise puzzle height (zoom, window size, etc.). I can reproduce the problem by opening a tall puzzle and calling
ui.puzzle.painter.resizeCanvasByCellSize(47);
with various arguments (sometimes it's fine, sometimes not). Looks like there's probably a rounding error somewhere...