#home{   
      filter:alpha(opacity=50);   
      -moz-opacity:0.8;   
      -khtml-opacity: 0.8;   
      opacity: 0.7;   
}
body{
background-image:url(https://images.cnblogs.com/cnblogs_com/dcoi-king/1074636/o_64960369_p0_master1200.jpg);
background-size:600px 900px;
background-attachment:fixed;
}