Modifying global CSS in style manager

We want to achieve the following:Mark our block HTML elements with some classes like:Add some styles that define CSS classes like:Using GrapesJS style manager we want to change the above CSS classes so we can have a "Container background color" setting which can change the "background-color" of the ".my-container" rule Why we want this ? We want to use some kind of "theming" for the page which can be changed by the user - we don't want the user to click on the elements to change their style. And more - we want to remove almost everything from the Style Manager - it is way too complex for the...