When using the table rendering method, highlighted squares don't stay the same size as unhighlighted squares so the board ends up shifting around a lot when looking at move options.
This depends on the size of the individual piece, though some sets, such as Alfaerie, maximize the dimensions of the piece images, so that you may see this effect for every piece.
Is this fixable?
If you made your spaces larger than the largest pieces, you might leave enough room for a border around the piece image without expanding the size of the space. 54x54 might work better than 50x50, for example. However, the square size for the Table method is determined by the $height and $width values, which are provided in the set file, and these are usually set to 50 for the Alfaerie sets.
At least the css rendering doesn't have this problem
One of the reasons to start favoring the CSS rendering method.
This depends on the size of the individual piece, though some sets, such as Alfaerie, maximize the dimensions of the piece images, so that you may see this effect for every piece.
If you made your spaces larger than the largest pieces, you might leave enough room for a border around the piece image without expanding the size of the space. 54x54 might work better than 50x50, for example. However, the square size for the Table method is determined by the $height and $width values, which are provided in the set file, and these are usually set to 50 for the Alfaerie sets.
One of the reasons to start favoring the CSS rendering method.