#top{


    height: 50px;
    background-color: black;
 
padding-top:5px;
 overflow:auto;
}

#top h1{
    display:inline;
    }

#subtitle{
     position:absolute;
     top:31px;
     left:100px;
     font-size:9px;
     font-family:"Times New Roman", Times, serif;
    }

#main_container{
    clear: both;
}
#top:before{
    content:url(https://images.cnblogs.com/cnblogs_com/zd1994/1252438/o_docker1.png);
float:left
}
#main_container{
opacity:1;
  filter:alpha(opacity=100); /* For IE8 and earlier */
}
#sidebar_categories ul:first-of-type{
    position:absolute;
    top:0px;
   overflow:auto;

   width:70%;
   left:200px;
   padding:10px;

}

#sidebar_categories ul:first-of-type li{
display:inline;
margin-right:20px;
height:20px;
line-height: 20px;
float:left;
}

#sidebar_categories ul:first-of-type li a{
color:#aaa;
opacity:1;
  filter:alpha(opacity=100); /* For IE8 and earlier */
}
#sidebar_categories ul:first-of-type li a:hover{
background:#000;
}

body{
background-color:rgb(64, 64, 64);background-image:url("https://ss3.baidu.com/-fo3dSag_xI4khGko9WTAnF6hhy/super/crop=0,0,1220,764/sign=ae68e097b8a1cd1111f928608422e4cc/d4628535e5dde711c65b4751a5efce1b9c16618f.jpg");
}

#footer,#footer a{
color:#fff;
}