Can Apps control/modify/add any styles/css to a Help Center Article?

Hi All,

I’m looking to add a custom CSS to my articles.
The focus is on the articles that our customers can see via our Customer Portal (Help Center).

  • we write articles in our knowledge-base and they can be searched using the help center
  • we are too happy with the current CSS and wish to update it

So my question is:
If I write an app for Confluence, will it have the required scope/access right to push CSS into these pages?

Thank you!