Remove bottom margin on close button

[iamacook]

What it solves

Resolves #2759

How this PR fixes it

All bottom margins on close buttons were removed.

How to test it

• Open modals
• Hover over close button and bserve the circular, centralised background

Screenshots

[github-actions]

CLA Assistant Lite All Contributors have signed the CLA.

[github-actions]

ESLint Summary View Full Report

Annotations are provided inline on the Files Changed tab. You can also see all annotations that were generated on the annotations page.

Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	0	N/A

• Result: ✅ success
• Annotations: 0 total

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^{Report generated by eslint-plus-action}

[coveralls]

Pull Request Test Coverage Report for Build 1650109053

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 32.273%

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Totals
Change from base Build 1649934226:	0.0%
Covered Lines:	3085
Relevant Lines:	8492

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💛 - Coveralls

[github-actions]

Deployment links

🟠 Safe Rinkeby	⚪ Safe Mainnet	🟣 Safe Polygon	🟡 Safe BSC	⚫ Safe Arbitrum	🟢 Safe xDai

[github-actions]

E2E Tests Failed
Check the results here: https://github.com/gnosis/safe-react-e2e-tests/actions/runs/1650136713

Failed tests:

• ❌ Read-only transaction creation and review Read-only transaction creation and review
• ❌ Safe Balances Safe Balances

[katspaugh]

👏

[francovenica]

Looks good to me.
Checked it in chrome, FF and Brave