z-index may be too high

**Is your feature request related to a problem? Please describe.**
z-index appears to be very high for $cf-z--* properties

**Describe the solution you'd like**
A lower z-index, maybe in the hundreds rather than thousands. Or even lower if possible. I'm not sure why z-index has to be so high. There may be a reason that I am unaware of.

**Describe alternatives you've considered**
We have bumped z-index in another library's component. But this seems like an "arms race" rather than a solution.

**Additional context**
We have also made a request to allow z-index to be configurable in the other library.

The issue names the $cf-z--* properties but no file, test, or entry point. Start by locating those properties and reviewing their current z-index values and usage across components; done would require an agreed lower scale that avoids conflicts with consuming libraries.

Written by the indexing model from the issue text.