Three column layout

/*
#nav{
    border: 1px solid red;
}
#nav:after{
    content: '';
    display: block;
    clear: both;
}
#nav .plate-group .plate-item{
    float: left;
    margin-right: 30px; ;
}
#nav .login-group .login-item{
    float: left;
    padding-right: 30px;
}





   <link rel="stylesheet" href="{% static 'css/user_manage.css' %}">
<div id="nav">
    <ul class="plate-group">
        <li class="plate-item">123</li>
        <li class="plate-item">哈哈哈</li>
        <li class="plate-item">sss</li>
    </ul>


    <ul class="login-group">
        <li class="login-item">登录</li>
    </ul>
</div>

*/