Adjust panel styles for persistent header/footer messages

What does this MR do and why?

Adjust panel styles for persistent header/footer messages

Changelog: fixed

References

• &19602

Screenshots or screen recordings

	Before	After
Project Studio
Legacy UI		No change

How to set up and validate locally

1. Go to Admin > Settings > Appearance
2. Add text for header and footer messages within System header and footer section
3. Save and reload the page, the persistent header/footer messages should now appear.
   • Without changes in this MR, the messages will overlap the panel elements, causing it to appear clipped.

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #578134