html { 
  margin:0;
  padding:0;
  background: url(back.jpg) no-repeat center fixed; 
  -webkit-background-size: cover; /* pour anciens Chrome et Safari */
  background-size: cover; /* version standardisée */} 



a:hover
{ 
color: white; 
} 

a:
{ 
color: white; 
} 


a:visited 
{ 
color: white; 
}