Broken styles for single-column columns block

[carrieforde]

If a user manually enters 1 for a single column child in the columns block, the block inherits styling for the two-column block.

One of two things need to happen here:

1. Users shouldn't be able to enter 1 if the slider doesn't support it.
2. A style needs to be added for the single column block.

Here is an example of the code produced on the frontend:

[youknowriad]

Right now, it's not possible to enter "1" in the columns count, it automatically reverts to 2. This means this issue is fixed.