In fact, I stop using floating block module a couple of years ago, but recently I was contacted by another Drupal webmaster, regarding my tutorial on Floating Block module for Drupal 7 site and taking a fresh look at this module, I understood - Floating block module helps UI by filling up sidebar, so it's never empty.
When speaking about Floating block module for Drupal 8, there is not yet a stable release (as of writing this), but there is a dev version, which actually works out of the box.
Configure Floating Blocks for Drupal 8 website
As usual, let's start with download
- Download and enable floating block module
- Configure floating block from admin/config/user-interface/floating-block
In my example, I'm looking to make one block from the right sidebar to float.
Using inspector tool (Chrome CTRL+Shitf+I) find div (#) id element you are looking to make floating, in my case: #block-views-block-tours-block-2
To float the left sidebar within a container in your theme us selectors, for bootstrap: container=.main-container
Here is complete configuration for floating block configuration
#block-views-block-tours-block-2|container=.main-container
Feel free to drop a comment if you need any help.