CSS grid-auto-columns property

Description

When we do not specify the grid-template-columns to place an item or we place an item beyond the number of a columns, the implicit tracks are automatically created to place an item. And 'grid-auto-columns' specifies the size of those implicit tracks.

For example, we have a grid with a first column of size 20px explicitly define by grid-template-columns.

What If want to place an item in the second column that was not defined explicitly?

In this case, the second column is defined automatically. We define the implicit track size of second column with grid-auto-columns.