How to create bookmark at the very top of a page?

Using Writer 25.8.3.2, I have a document with a floating image with Wrap set as In Background. I have a Heading 1 text “Section 1” on the first line of the page, with a bookmark “sec_1”. The TOC and other links direct correctly to that bookmark, but the layout being displayed is now borked because the bookmark is not at the top of the page. Is there any way to set a bookmark on the image or set it at the same 0px coordinate that is the picture’s top?

Instead of asking for a fix on your current implementation, give a specification of your goal in typographical or geometric terms, independent of any office suite. E.g. the image is a companion of the heading. Its size is full page (or small size not related at all to page size). It should be located here or there (absolute top/bottom of page, below the header, in the vicinity of the heading, …). It is intended to be overlaid by text (suggested by your background property).

Give maximum information about it.

Don’t forget OS name and save format. The latter is particularly important because the solution probably relies on a frame style which exists only in .odt.

By the way, do you knwo what a frame style is and what is its use?

Explain why you have created a bookmark. A picture cannot be positioned relative to a bookmark.