/*
#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>
*/