Grid by Example

Everything you need to learn CSS Grid Layout

Line names on the child are added to those from the parent

If you define line names on the subgrid, these are added to any lines defined on the parent.

Line names are added to a subgrid, by listing the names after the subgrid keyword, for example grid-template-columns: subgrid [sub-1] [sub-2] [sub-3] [sub-4];.

Read the specification | View example as full page

See the Pen Grid by Example 2.7: lines on child are added to those defined on the parent. by rachelandrew (@rachelandrew) on CodePen.