Hi @seraph1976,
Thanks for the post.
To achieve this, you would need to create a conditional block to check for the value selected and then call a certain class within that selection.
For a single-value select field, the code would look like so:
if(get_field('select_field_name') == "value_1")
{
//call the class here
}elseif(get_field('select_field_name') =="value_2")
{
//some other class here
}