why not to use only flex box code example

Example: css grid vs flexbox

/* Answer to: "css grid vs flexbox" */

/*
  Grid is much newer than Flexbox and has a bit less browser
  support. That’s why it makes perfect sense if people are
  wondering if CSS grid is here to replace Flexbox.

  To be exact:
  1. Grid can do things Flexbox can’t do.
  2. Flexbox can do things Grid can’t do.
  3. They can work together: a grid item can be a flexbox container.
  A flex item can be a grid container.

  For more information on this topic, go to:
  https://css-tricks.com/css-grid-replace-flexbox/
*/