Specifies the collection of rows for the grid used to position layout elements.
The base height of the row.
The row height ratio.
Decides on which screens the current row is rendered.
Before rendering the row, the widget considers the screen's width. If the width matches the specified size qualifier, the row will be rendered. There are four size qualifiers in all. The screen option accepts one or several of them separated by a space.
|xs||Stands for "extra small". Screens with width less than 768 pixels.|
|sm||Stands for "small". Screens with width between 768 and 992 pixels.|
|md||Stands for "medium". Screens with width between 992 and 1200 pixels.|
|lg||Stands for "large". Screens with width more than 1200 pixels.|