Flexbox works with items that are all in the same div class, with no other item in that div class. If you don't use flex with a div class, then the flex properties you use will do absolutely nothing at all. However, you can assign another class to the content in your div class, with different styles that don't conflict with flex.
To organize content from a certain class (not tag) using flexbox, you have to put display: flex; in that class before proceeding. Then, you can put other flex properties to style that content. Here's an example:
This code yields the following result:
