File Blocks Alignment is not aligned in Center in editor for few themes

[pitamdey]

In few theme like twenty sixteen , twenty seventeen, twenty eighteen the file alignment is not working proper. Here we can not set the alignment centre in the editor side.
Here is the video of the difference like how they look in other themes and with this themes:
​https://www.loom.com/share/e623dfeaad7c4aa5a7db3e7012b6dcfc?sid=f52f128c-7a55-4a43-93ba-6b619d4ea2f1