Closes #765: Imagify plugin banners are not styled

[jeawhanlee]

Description

This PR fixes the unstyled banners of imagify.

Fixes #765

Type of change

• Enhancement (non-breaking change which improves an existing functionality).

Is the solution different from the one proposed during the grooming?

No

Checklists

Generic development checklist

• My code follows the style guidelines of this project, with adapted comments and without new warnings.
• I have added unit and integration tests that prove my fix is effective or that my feature works.
• The CI passes locally with my changes (including unit tests, integration tests, linter).
• Any dependent changes have been merged and published in downstream modules.
• If applicable, I have made corresponding changes to the documentation. Provide a link to the documentation.

Test summary

• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I validated all Acceptance Criteria of the related issues. (If applicable, provide proof).
• I validated all test plan the QA Review asked me to.

If not, detail what you could not test.

Please describe any additional tests you performed.