Columns
A .. grid::'s argument is a column count, and a .. grid-item::'s
:columns: is how many of those columns one cell spans. Both accept one
value — applying at every breakpoint — or four, read as xs sm md lg, and both
accept auto.
The argument
Three cells to a row, at every width:
First
Second
Third
One cell to a row while narrow, four once there is room — the four-value form:
xs: 1
sm: 2
md: 3
lg: 4
A grid written with no argument at all is legal; the row then carries no column classes and the cells share the width evenly:
No argument
was written.
The :columns: option
A cell may take a different share of the row than the argument gives it. In a twelve-column row, a wide cell beside a narrow one:
:columns: 9
:columns: 3
auto asks for only as much width as the content needs:
auto
is as wide as its text.