The <Page> component is what you have to wrap all your Timvir pages with.
The component provides a common React Context to all its children which contains everythin that the blocks require for rendering.
It also sets up some CSS variables which the blocks and your own components can use for styling.
A CSS class which makes the element display: grid, and establishes a centered five column grid. It is used
internaly by <Page>. This class is exported if you want to replicate the grid used by <Page> in your own
custom components.