Adding additional classes to blocks sometimes breaks styles

I've noticed this issue with the Columns block, but it might be present in other blocks with styles too... 

Basically if you add a new class after the style one that is already there, the style won’t work anymore because of this check… So for now we need to add classes before the style one in order not to break the block style.

Tasks

• Fix the issue in Columns block
• Check if it's happening in other blocks with styles and fix it there too