not minimal: Minimalism is not the goal of briefscss, clear design hierarchy is.
not batteries-included: You're most likely going to have to write your own css. briefscss is more meant to enforce a design system than it is to be a component framework.
In briefscss, spacing is a multiple of 4px, generally either 16px or 24px.
All "elements" are designed with a built-in top and bottom margin. These margins differ based on the element. Certain elements will have larger margins because they deserve more space. Margins also differ based on their position: first child elements do not get margin-tops, while last child elements do not get margin-bottoms.
Elements with class .is-inline do not establish vertical margins and instead establish horizontal margins.