a basic grid system ?
- usually it's based on the 960.gs system
- it has 12 columns
- colums are contained in a row
- a row is contained in a container
- you usually have 4 mobile break points which override the previous hierarchical lg -> md -> sm -> xs | l -> m -> s -> x
- you have to be able to define offset to the left or right based on the view and hierarchy
- they have to be composable md-4 + md-offset-left-4 so as atomic as possible
- since you usually work in percentages you have 2 basic types -> fluid (full width) and the 1024px - scrollbar container ~ 955px so it works on a 15" monitor
I forgot something for sure but those are my first thoughts.