The body is the relevant content of a web page, excluding the navigation bar, footer, modal views, etc.
Be consistent, reuse components. Apply your design system to the body, just as you would for the other elements.
Make sure it’s fully responsive. Like the rest of the components, the body must be totally responsive. Also be careful not to take all the space on the large screens: set a maximum width, and center the body if this value is exceeded.