Oxygen 6: Header Builder sticky position outputs relative instead of sticky

[gerogr]

Describe the bug
When enabling sticky position in the Header Builder, the generated CSS incorrectly keeps the element as position: relative instead of position: sticky.

As a result, the sticky behavior does not work unless manually overridden with:
position: sticky !important;

This indicates that the builder is not properly applying or overriding the position property.

Steps required to reproduce the bug:

1. Create a header using the Oxygen Header Builder
2. Set the header to sticky
3. Save and view the page on the frontend
4. Inspect the header element in the browser dev tools
5. Notice that position is set to relative instead of sticky
6. Sticky behavior does not work unless manually overridden