Summary

Sidebar can, when scrolling up the page quickly, overlap the Custom HTML.

Steps to reproduce

1. Attach an image in Confluence
2. Go to Custom HTML in admin section
3. Add at beginning of the BODY, for example:

   <img src="/confluence/download/attachments/327683/i%CC%81ndice.png">
   

4. Save and scroll down and then up quickly

Expected Results

Page is displayed normally while scrolling up

Actual Results

Sidebar overlaps image. See video

Workaround

Scrolling again will display it normally