Update header css

[timwlee]

Please always provide the GitHub issue(s) your PR is for, as well as test URLs where your change can be observed (before and after):

Fix #

Test URLs:

• Before: https://main--{repo}--{owner}.aem.live/
• After: https://--{repo}--{owner}.aem.live/

[aem-code-sync]

Hello, I'm the AEM Code Sync Bot and I will run some actions to deploy your branch and validate page speed.
In case there are problems, just click a checkbox below to rerun the respective action.

• Re-run PSI checks
• Re-sync branch

Commits

• 89627c7 ✅ (latest)

[github-actions]

⚠️ Block Changes Detected

This PR contains changes to the following blocks:

• ❌ blocks/header/ (missing README.md)

📋 README Requirements

Please ensure the README.md for each changed block includes:

• Overview: Clear description of the block's purpose and functionality
• Configuration: All configuration options, their types, defaults, and side effects
• Integration: URL parameters, localStorage usage, and event handling
• Behavior Patterns: User interaction flows and page context detection
• Error Handling: How the block handles errors and fallback scenarios

⚠️ Action Required

The following blocks are missing README.md files:

• blocks/header/README.md

Please create these README files before merging this PR.

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This comment was automatically generated by the Block README Check workflow.