Box model: can be seen as a box, including margins, borders, padding, actual content.
flex Layout: Layout elasticity, good flexibility.
When the element is set to display: flex, it is flex container, all of its child elements automatically become members of the vessel, called flex project, referred to the project.
The container has the properties: display, flex-direction, flex -wrap, flex-flow, justify-content, align-items, align-content
program has attributes: order, flex-grow, flex -shrink, flex-basis , flex, align-self