.c_ad_block{
   background:#fff;
   height:0px;
   width:700px;
   overflow:hidden;
}

#site_nav_under{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
#opt_under_post{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
.ad_text_commentbox{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
#g_container_code{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
#g_code_sw{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}

#ad_t2{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
#ad_c1{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
#ad_text_under_commentbox{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
.ad_text_commentbox{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
.c_ad_block{
   background:#f00;
   height:0px;
   width:700px;
   overflow:hidden;
}
.box{
   border: 1px solid #cfcfcf; 
   background: #F0F8FA; 
   padding: 5px; 
   margin:3px;
}

iframe{
    height: 20;
    width: 20;
    border: 5px;
    
}
#main{
    background: #F0F8FF; 
}
#mainContent{
    background: #FFF; 
}
body{
    background-image: url("https://img2018.cnblogs.com/blog/829863/201809/829863-20180919090656500-190786919.png");
}