Holy grail layout

For this classic holy grail layout, there is a header, footer, left sidebar, right sidebar, and main content. It's similar to the previous layout, but now with sidebars!
To write this entire grid using a single line of code, use the 
grid-template property. This enables you to set both the rows and columns at the same time.
The property and value pair is: 
grid-template: auto 1fr auto / auto 1fr auto. The slash between the first and second space-separated lists is the break between rows and columns.
.parent {
  display: grid;
  grid-template: auto 1fr auto / auto 1fr auto;
}
As in the last example, where the header and footer had auto-sized content, here the left and right sidebar are automatically sized based on their children's intrinsic size. However, this time it is horizontal size (width) instead of vertical (height).