Trianglular Grid - Display Size

[swaroopg92]

Describe the bug
Changing the display size of the triangular grid does not center the grid and shifts downward there by cutting some of the given cells.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://git.io/JP4XQ (Puzzle from https://puzzles.covering.space/49/)
2. Click on Resize
3. Change to 50
4. See the cut-off cells from the bottom

Expected behavior
Grid cells should not be cut off.

Possible Solution
Enable move grid to center option to the user? (Its there only in Setting Mode)