Fixing the issue "The Fluidui widget loads below the pages / node pages" for the 8.x-1.x branch

Problem/Motivation

In the branch 8.x-1.x, address the issue mentioned here: https://www.drupal.org/project/fluidui/issues/3508931

I can't open that issue because it's closed, that's why I opened a new one

Steps to reproduce

Set "olivero" as the default theme, install the 8.x-1.x version of the fluiduimodule, you'll see that the header covers the widget. This probably is an issue in other themes.

Proposed resolution

CSS changes

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A