body,html{
    height: 100%;
}
header{
    height: 50px;
    box-shadow: 0 0 5px #b7b7b7;
}
header a{
    width: 50px;
    height: 50px;
    line-height: 50px;
    text-align: center;
    display: inline-block;
    color: #000;
}
header img{
    cursor: pointer;
}
header a:hover{
    text-decoration: underline;
}

header .top_tt {
    width: 1000px;
    text-align: right;
    margin: 0 auto;
}

header .top_tt img {
    float: left;
    margin-top: 5px;
}

.content{
    width: 1000px;
    margin: 0 auto;
}

.protocol_header {
    color: red;
    font-size: 20px;
    text-align: center;
    margin-top: 50px;
    margin-bottom: 20px;
}

.protocol_body {
    text-align: justify;
    margin:0 auto;
    line-height: 25px;
    padding: 0 40px;
}

footer {
    position: absolute;
    margin-bottom: 30px;
    width: 100%;
    z-index: 0;
    overflow: hidden;
}