Update style for banner message ui

[AllForNothing]

1.Fixes #19021
2.Fixes #19022

Thank you for contributing to Harbor!

Comprehensive Summary of your change

Issue being fixed

Fixes #(issue)

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

Merging #19069 (e26b725) into main (28e6a99) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #19069      +/-   ##
==========================================
- Coverage   67.40%   67.39%   -0.01%     
==========================================
  Files         992      992              
  Lines      108751   108751              
  Branches     2749     2749              
==========================================
- Hits        73303    73295       -8     
- Misses      31517    31520       +3     
- Partials     3931     3936       +5     

Flag	Coverage Δ
unittests	67.39% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 8 files with indirect coverage changes

[wy65701436]

lgtm