Compatible with four-corner fixed background code in IE 6 Browser

Yesterday, a netizen asked "How to place images on the four corners of the HTML page". The answer is as follows for the Netizen's reference.

 1   <!  Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"  > 
 2   <  Html  Xmlns  = "Http://www.w3.org/1999/xhtml"  > 
 3   <  Head > 
 4   <  Meta  HTTP-equiv  = "Content-Type"  Content  = "Text/html; charsets = UTF-8"   /> 
 5   <  Title  > Fixed background of Four Corners of browser window Code  </  Title > 
 6   <  Style  Type  = "Text/CSS"  >  
  7   Html  {  
  8   _ Overflow :  Hidden  ;  /*  For IE6  */  
  9   }  
  10   Body  { 
  11   Margin  :  0  ;  
  12   Padding  :  0  ; 
  13   _ Height  :  100%  ;  /*  For IE6  */  
  14   _ Overflow :  Auto  ;  /*  For IE6  */  
  15   }  
  16   . Mainbox  { 
  17   Position  :  Relative  ;  
  18   _ Position  :  Inherit  ; /*  For IE6  */  
  19   Margin  :  20px  ;  
  20   Display :  Block  ;  
  21   Height  :  2000px  ;  
  22   Background :  # E2e2e2  ;  
  23   }  
  24   . Topleft,. topright,. bottomleft,. bottomright  {  
  25  Position  :  Fixed  ;  
  26   Width  :  100px  ;  
  27  Height  :  100px  ;  
  28   Background-color  :  #990  ;  
  29  _ Position  :  Absolute  ;  /*  For IE6  */  
  30   _ Z-Index  :  -1 ;  /*  For IE6  */  
  31   }  
  32   . Topleft  {  
  33  Left  :  0  ;  
  34   Top  :  0  ;  
  35   } 
  36   . Topright  {  
  37   Right  :  0  ;  
  38   Top :  0  ;  
  39   }  
  40   . Bottomleft  {  
  41   Left :  0  ;  
  42   Bottom  :  0  ;  
  43   }  
 44   . Bottomright  {  
  45   Right  :  0  ;  
  46   Bottom  : 0  ;  
  47   }  
  48   </  Style  > 
 49   </  Head  > 
 50  <  Body  > 
 51   <  Div  Class  = "Topleft"  > </  Div  > 
 52   <  Div  Class  = "Topright"  > </ Div  > 
 53   <  Div  Class  = "Bottomleft"  > </  Div  > 
 54   <  Div  Class  = "Bottomright"  > </  Div > 
 55   <  Div  Class  = "Mainbox"  >  Here is the text filled in the content area  </  Div  > 
 56   </  Body  > 
 57   </ Html  >