Set z index on table cell div for each row in angular material

I'm trying to set z index/overlayed div on each row's cell which is having expandable effect on icon click.

Issue here is it(icons) expands column even I gave z-index for overlaying it over other(left side) columns instead. Expectation here is it shouldn't expand column width, instead of that it should overlay left side for every icons.

Here is StackBlitz for the same where it is expanding column.

from Set z index on table cell div for each row in angular material