Alternative

Source: https://www.loom.com/share/b921a893d6f84cf5821c325b04ddffc6

1. In the theme builder, create a header with a section, row and menu module
2. In section » advanced » scroll effects, set sticky position to top
3. In section » content » background, you can set the regular background color (or transparent) and a different sticky color.
4. In section » advanced » css » module elements » main element, add the css below

CSS for section

position: absolute !important;
Code language: HTTP (http)

Elegant tutorial

Source: https://help.elegantthemes.com/en/articles/14003959-how-to-create-a-transparent-fixed-header-layout-that-overlaps-the-page-s-content-in-divi-5

1. Follow step 1 to 3 from above.
2. Also set a minimum height for the section when sticky.
3. Then go to the row and set the position to absolute.