Editing in Simple CSS overview

Generate Press is a good add-on. Nice work.

To assist in editing the style parameters of individual Generate Press pages, do you have a list of CSS elements specific to GP (e.g.: body, container, etc.) that adjust the look and shape of a page, and which can be edited in Simple CSS.

It has been trial and error so far, and this is the only CSS edit that I have managed to implement on an individual page:

body .grid-container {
max-width: 800px;
}

I would also like to change the background color of the container, but would like to know what other CSS elements and properties can be edited (rounded corners anyone?). It would be handy to have a Master Style Sheet for GP that could be cut and pasted, then edited as needed. Comments? Suggestions?

Thanks