Remove z-index of overlay

[bram2202]

Fixes #86 - showing lock icon under pop-up window

Removed z-index, tested locally:

[ildar170975]

This is WRONG.
It makes the card not working.

[Mariusthvdb]

yes, please dont generically change resources for personal styling challenges.

would be appreciated by the community if this were reverted.
since it is such a simple change, no real harm is done, but please fix, so the new users will get the correct experience.

if you need some finetuning, use things like:

  type: custom:mod-card
  card_mod:
    style: |
      ha-card {
        z-index: 1;
        }
  card:
    type: custom:restriction-card