header,nav,section,footer{
    margin:0 auto;
}
body{
    font:18px "Microsoft YaHei";
    margin:0;
}
ul,ol,li,p,h1,h2,h3,h4,h5,h6,dl,dt,dd{
    margin:0;
    padding:0;
    list-style:none;
}
input{border:none;}
.lt{float:left;}
.rt{float:right;}
.clear{clear:both;}
a{
    text-decoration:none;
    color:#000;
    outline: none;
}
a:hover{
    color:#000;
    text-decoration:none;
    outline: none;
}
a:focus{outline:0}
.clear-float:after{
    content:'';
    display: block;
    clear: both;
}