Add new class programatically

Hello Artf,

I want to edit the styles of components (mostly imported html) without modifying all components with the  same class. I tried to add a random named class programmatically  like this:
`
      this.editor.on('component:selected', function(model) {
if (model && model.length > 2) {
                const uuid = this.s4(); // generate new random class name

                const selector =  {
                    name: uuid,
                    type: 'class',
                    label: uuid,
                };

                model[1].attributes.classes.push(selectorManager.get(uuid));
     let mClasees = model[1].attributes.classes;
             const uuid = this.s4();
             const selector =  {
                 name: uuid,
                 type: 'class',
                 label: uuid,
             };
          mClasees.push(selector);

      
}.bind(this));
`

This add a class programmatically to the component but it seem to no let me edit it's style. 

I just want be able to change the style of a single component without having to care which class it belongs to. Event if I copy past a component, I want be able to edit each components individually.
I hope that clear. If you need any further information, don't hesitate to ask me :) 
Thanks your help!