Here I use Styles to change divs. I put a blueviolet background and a white color text for that I refer to div and then use {} to add attributes

Now I have a paragraph with a class and it has its own style. I refer to this class using a dot (.) right before the class name

Now I have a header or title with a unique ID. I refer to this id using # right before the id's name

you can check the css code here