问题
In this series they all used a wrapper div.
MDN - CSS GRID Layout
Is this necessary, and if yes, why?
回答1:
The purposes of wrappers are several, including:
- to group elements semantically, for instance to separate page heading from body text from sidebar from footer.
- to group elements cosmetically, such as with a surrounding border or a common background image or color.
- to group elements in layout, such as to keep them all in the same column when columns are floated next to one another.
- to enable special positioning, as when a wrapper is given relative positioning in order to contain child elements with absolute positioning.
- to make it more convenient to specify elements in CSS and JavaScript by referring to their parent, without having to id or class each child element.
(Note: the var above should all be on one line)
So in this case, i think they all used a wrapper div just to group elements in layout.
来源：https://stackoverflow.com/questions/52662833/css-grid-nested-in-a-wrapper-div-or-a-body-element