The flex-direction Property

The flex-direction property defines in which direction the container wants to stack the flex items.

The column value stacks the flex items vertically (from top to bottom):

 .flex-container{
  display: flex;
  flex-direction: column;
} 

The column-reverse value stacks the flex items vertically (but from bottom to top):

 .flex-container { 
  display: flex;
  flex-direction: column-reverse;
} 

The row value stacks the flex items horizontally (from left to right):

 .flex-container {
  display: flex;
  flex-direction: row; 
}

The row-reverse value stacks the flex items horizontally (but from right to left):

 .flex-container {
  display: flex;
  flex-direction: row-reverse;
}