padding(內距) 與 margin(外距)

資料來源：http://www.w3schools.com/css/

• padding(內距) : The padding clears an area around the content (inside the border) of an element. 
• margin  (外距) : The margin clears an area around an element (outside the border). 

padding/margin基本語法範例：

• 4個值:上 右 下 左; 2個值:上下 左右;　3個值:上 左右 下;　1個值:四個邊同樣値;

其它值：

Value	Description
auto	The browser calculates a margin
length	Specifies a margin in px, pt, cm, etc. Default value is 0px
%	Specifies a margin in percent of the width of the containing element
inherit	Specifies that the margin should be inherited from the parent element