Remove z index on thead style

[connor-bechthold]

Notion task link

N/A

Implementation description

Remove z index on thead so it doesn't cover search and filters dropdown

Steps to test

1.

What should reviewers focus on?

Checklist

• [ ] My PR name is descriptive and in imperative tense
• [ ] My commit messages are descriptive and in imperative tense. My commits are atomic and trivial commits are squashed or fixup'd into non-trivial commits
• [ ] I have run the appropriate linter(s)
• [ ] I have requested a review from the PL, as well as other devs who have background knowledge on this PR or who will be building on top of this PR
• [ ] If I have made API changes, I have updated the REST API Docs
• [ ] IF I have made changes to the db/models, I have updated the Data Models Page
• [ ] I have documented this PR in the Production Release Page
• [ ] I have updated other Docs as needed

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit e18e7fc):

https://blueprintsupportivehousing--pr216-connor-z-index-bug-07cge240.web.app

_{(expires Mon, 11 Dec 2023 03:13:54 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}

_{Sign: f6bcdba7452bf82a6ec1a299c37d1bdff7870d09}