CSS Box Model

Border is margin, border is padding within, padding is width & height.

margin vertical margin Overlay, horizontal margin not superimposed. (top right bottom left, like round clock, starting from 0 o'clock in the evening )

width , the default value auto, expands the width of the element to its parent element.

Float:left or right;, Create a multi-column layout.

if a few adjacent elements are have a set width, are floating, and the horizontal space is enough to hold them, they will be lined up in Row,

If an element doesn't want to float,

Set the float:clear;

the parent element of the or floating element (if the parent element is different) Overflow:hidden; ( forcing the parent element the child element that contains its float)

The or also floats the parent element of the floating element ; (at this time the parent element cannot have space,width:100%; otherwise the following elements will squeeze up)

Or, set a point with no size, set to Float:clear;

CSS Box Model