When you name lines, you can optionally name them as *-start and *-end and this gives you a little more grid magic. We get a named grid area of the main name used. Sounds odd? Take a look at the diagram below, it shows 4 named grid lines, main-start and main-end both for columns and rows. The area marked out by the intersection of these lines can now be referenced by the name main. If we had named the lines foo-start and foo-end then we would have a named area called foo.
Rachel's post stood out to me for a number of reasons. First, I love blog posts as responses to other blog posts. Second, it's an excellent reminder that sharing how a concept works is equally as important as showing that it works. Lastly, the concept of implicitly named grid areas based on named grid lines is as good a reason as any to roll up our sleeves and get cozy with the spec. In fact, following Rachel's series on the CSS Grid spec is a good starting point.
As a side note, Tyler's clever use of named Grid lines reminded me of Dave Rupert's equally crafty use of :not to achieve a similar full bleed effect.