The grid consists of four key parts: the Container, Container Margins, Columns, and Gutters.
All columns reside within the Container, which is located at the root level of a page. Depending on the breakpoint, the container will have Container Margins of various sizes. The container also has a maximum width property, beyond which only the container margins grow in size.
The container is divided into 12 proportional Columns which contain actual content. These are separated by Gutters of a fixed size (which varies based on the breakpoint again).
See the redlines for the exact dimensions of each feature at each breakpoint.