html,
body {
    min-height: 550px;
    max-width: 900px !important;
    margin: 0 auto !important;
}

header {
    display: flex;
    border-bottom: 1px solid #e5e5e5;
    padding: 3px 0;
}

header .header-logo {
    width: 100px;
    height: 50px;
    background: url(https://ddyyxc-1254110062.image.myqcloud.com/book/login/header@2x.png) no-repeat;
    background-size: cover;
}

header .header-title {
    flex: 1;
    border-left: 1px solid #e8e8e8;
    margin: .5rem;
}