How to implement the effect when hovering and sorting blocks?

Question

css

Good afternoon!
Help with advice or a link to a tutorial on how to implement the following effect.
In general, I have a timeline with the effect of sorting blocks, the number of blocks in which will be dynamic.


It is necessary that when sorting, the field that shows where the block is inserted should have an element - shown as a blue dot on the screen. And with further dragging of the block, this point moved smoothly
along the timeline.

I once saw such an implementation when hovering on the menu, but I can’t find it :(

Answer 1

And what does hover have to do with it? It's drug&drop. Drag and drop to add a class, to it in css styles, whatever you want. In the picture, as I understand it, transparency is simply added to the block:
You can, of course, hang it on hover.
.someSelector:hover {opacity:0.5;}