CSS FlexBox is a layout model for one-dimensional layouts. You can choose to place items either along the X-axis or the Y-axis (but not both). A flex container is flexible meaning it expands the items to fill space when it is available and shrinks the space when it is not. With Flexbox, you can lay out and align elements in a container even if you don’t know the size of those items.
NOTE: You can put a FlexBox container inside of a CSS Grid but you cannot put a CSS Grid inside of a FlexBox container.
Try creating a web page with a CSS Flexbox. Spend at least one hour on this topic because CSS flexbox is used quite often in web design so you need to be confident on this topic.