Principle 1 floating to make the following words: floating elements from the document flow, float above the normal flow, 2 floating element is still in the normal flow according to its position, and then as far as possible according to the floating direction of the setting that float to the left or right until the outside edge of the floating element contains a box or another floating element, and allows the text and inline elements around it, three floating creates a block-level box (equivalent to set the display: block), and no matter what is the element itself, remove floating methods: 1 for the floating element append an empty block level elements with clear: both
