z-index of flags

[danieldanielecki]

Even though tried many times to reduce z-index of .selected-flag for example, and still getting exactly the same behaviour as on the image, i.e. whatever z-index will make in the .scss files (tried also in global) somehow it's bigger than my sidenav. Obviously tried to use even very large numbers for z-index of sidenav and same nothing changed. I'm using Angular Material, and tried to overwrite its styles as well, didn't work.