#main{
    background-color:rgba(250,250,250,0.7);
}
#mainContent{
    background-color:rgba(250,250,250,0.7);
}
body{
    background:url("https://files-cdn.cnblogs.com/files/blogs/689258/bkgd.bmp");
    background-attachment: fixed;
    background-size: cover;
    background-position: center;
}
#top_nav{
    display: none;
}
.postTitle{
    
}