CSS Flexible Box Layout Model, also known as "flexbox", is a part of the draft CSS3 specification. It provides a CSS Box Model optimized for user interface design. Children in the flex layout can be laid out in any direction and have flexible dimensions to adapt with the space available. Positionning those children can be accomplished easily, and complex layout can be achieved in a simpler and cleaner way. The display order of the elements is independent from the order in the source code.