How do I add pre-set Bubble styles to a custom plugin element?

Hello! I am making a custom plugin for one of my projects, which includes two custom elements: (a) a select / dropdown, and (b) a div that contains text. I’d like Bubble to recognize the first as a “Dropdown Input Form” and the second as a “Text Visual Element” so that I can apply pre-set styles and make these custom elements uniform in style with the rest of my application.

Is there a way to do this, or do I have to reinvent the wheel with custom CSS for plugin elements?