1, usually Padding the default value is 0, the background-color default value is transparent.    However, in different browsers default value may be different.    If fear of a conflict, in the style sheet can be a first definition of the beginning of all the elements of Margin and padding value to 0, like so: 
  * ( 
  Margin: 0; 
  Padding: 0; 
  ) 
  2, a label can be a number of class definition.    For example: We have two first definition of the pattern, a pattern Background # 666; second form 10 px borders. 
  . One (width: 200px; background: # 666;) 
  . Two (border: 10px solid # F00;) 
  In the page code, we can call this 
  <div Class="one two"> </ div> 
  3, in order to save bytes, I propose not to quote the background picture path, because quotes are not necessary.    For example: 
  Background: url ( "images /***. gif") # 333; 
  Can be written as 
  Background: url (gif images /***.) # 333; 
  If you add quotes, but will lead to some wrong browser 
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  After the supplementary