Is it possible to specify more flexible column sizes in bootstrap?

Question

HTML

It often happens that a block should be slightly larger than "col-md-4", but less than "col-md-5" (otherwise there will be no room for others).
How to set something like this:

<row>
   <col-md-4.5>
   <col-md-3.5>
   <col-md-4>

Answer 1

Bootstrap - always 12, integers only.

Answer 2

Create your own class.. Well, ideally, go to the bright side of the force and use preprocessor mixins.