3 Column Row
At wide browser settings, the columns are inline. Each requires a width. A column width can be a fixed number of pixels or one fractional unit. At least one column must have a width of "1fr"
At the break point all the columns have a width of 1 fractional unit. The first two items remain in row one and the last item switches to row 2.
On mobile phones in portrait mode, all three columns occupy a row of their own.
The columns have controls for adding padding, border width, color and radius and for adjusting the grid gap.