Please look at this Code Pen: https://codepen.io/will_beaumont/pen/GRGazMr

As you can see, the ul element has a grid layout, and in particular it has justify-content set to space-between. The latter behaves exactly as you would expect it to if this were a flex layout, spreading out the columns and ensuring that the last column's right edge lines up with the right edge of the container.

Yet, Chrome grumbles about this when you inspect the list. In the Styles tab, it grays out justify-content: space-between; and puts an icon next to it that when you mouseover shows this message: The display: grid property prevents justify-content from having an effect. Try setting the display: grid property to display: flex. Clearly this is not true. Just uncheck justify-content and you'll see it has an effect. What is the meaning of this warning really? Is it trying to hint that justify-content will no longer be supported on grid layouts in future versions? That's what I worry about.

EDIT: Fixed grammatical error