Hello,
this is very specific and maybe of no value for the community.
Anyhow, I would like to mention it.
I want to place a SQL fetched image behind a nested (2 columns) row. Image will be dynamic.
Explainition:
I have 2 rows, and row 1 will fetch a background image. The second row is a nested (2 columns) row with user image and user name (custom module). I could come up with a custom module that would take care of everything, but if I could set z-index: -1 with Joomla Module > Positioning > Absolute for row 1, I would achieve the same result in a cleaner way. Currently we can only choose positive z-index (1 to 5). Maybe there are other used cases, where community members could make use of negative z-index.
This is just a suggestion and has no priority. I know you are probably working hard on CSS em and %, which I can't wait for to explore. With Joomla you have chosen a very powerful CMS, compared to Wordpress, Drupal and other CMS.