i need to create a plugin that allows me to select any button or any part of the website and add extra css to it ,i have manages to consumer rest api within wp ,add menus and submit forms but i have no idea how to accomplish this task ,i would appreciate any suggestion thanks
I think it's worth studying how other plugins work, for example: Visual Composer.
The logic that came into my head, is to pick the element selector clicked with jQuery, and work on it. Read this that may help you: https://stackoverflow.com/questions/5706837/get-unique-selector-of-element-in-jquery
Following this logic, if each page element has the same class, it will be easier to work with