Main axis and cross axis

• The concept of axes is critical to understand to work properly with flexbox.
• By default flexbox use flex-direction:row so the main axis is horizontal and the cross axis is vertical.
• But we can changes the axes by using flex-direction, instead of row you can use column.
• flex-direction:column will place our elements on column and change the main axis by vertical and the cross axis by horizontal.
• Axis are importants because it will affect properties like justify-content,align-content that we will see later.