求教一个css的有关问题

  <div class="page">

        <div id="header">
            <div id="title">
                <h1>Welcome to my blog</h1>
            </div>
              
            <div id="logindisplay">
                <% Html.RenderPartial("LogOnUserControl"); %>
            </div> 
            
            <div id="menucontainer">
          <% Html.RenderPartial("UserMenuControl"); %>
            </div>
        </div>

        <div class="main">
            <asp:ContentPlaceHolder ID="MainContent" runat="server" />

            <div id="footer">
            </div>
        </div>
    </div>

.page
{
    width: 90%;
    margin-left: auto;
    margin-right: auto;
}

#header
{
    position: relative;
    margin-bottom: 0px;
    color: #000;
    padding: 0;
}
div#title
{
    display:block;
    float:left;
    text-align:left;
}

#logindisplay
{
    font-size:1.1em;
    display:block;
    text-align:right;
    margin:10px;
    color:White;
}
#menucontainer
{
    margin-top:40px;
   
}