Definition of block-level elements and inline elements

UnderCSS specification, each page element has a display property, to determine the type of the element, each element has a default display property value, such as a div element, its default display property value is "Block", which becomes the blocks-level element (block-level), while the default display property value of the span element is "inline", called the "inline " element.
Div such a block-level element , will automatically occupy a certain rectangular space, you can set the height, width, internal and external margins and other properties to adjust the appearance of this rectangle; In contrast, inline elements such as "span" and "a" do not have their own independent space, which is attached to other block-level elements, so that properties such as height, width, and internal and external margins are not valid for inline elements

Definition of block-level elements and inline elements