This establishes the grid.
Smaller viewports
Between 0px and 767px
grid-template-columns: [full-start] minmax(20px, 1fr) [main-start] minmax(0, $max-width) [main-end] minmax(20px, 1fr) [full-end];
Larger viewports
From 768px and up
grid-template-columns: [full-start] minmax(40px, 1fr) [main-start] minmax(0, $max-width) [main-end] minmax(40px, 1fr) [full-end];
https://styleguide.asce.org/section-layout.html#asgref-layout-grid-columns