iframe调用网页遮住左上角菜单


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link href="__PUBLIC__/css/css.css" rel="stylesheet">
<title>标题</title>

    <script src="__PUBLIC__/static/jquery-2.1.1.min.js"></script>
    <script src="__PUBLIC__/static/layer/layer.js"></script>
        <script type="text/javascript">
            function openNav() {
    document.getElementById("mySidenav").style.width = "98%";
}
function closeNav() {
    document.getElementById("mySidenav").style.width = "0";
}
        </script>
        <style type="text/css">
         
            
            
            
            body {
                font-family: "Lato", sans-serif;
            }
            .sidenav {
                height: 100%;
                width: 0;
                position: fixed;
                z-index: 1;
                top: 0;
                left: 0;
                background-color: #17202A;
                overflow-x: hidden;
                transition: 0.5s;
                padding-top: 60px;
                text-align:center;
                
            }
      .sidenav a {
          padding: 8px 8px 8px 32px;
          text-decoration: none;
          font-size: 25px;
          color: #7B7D7D;
          display: block;
          transition: 0.3s;
                }
      .sidenav a:hover{
          color: #f1f1f1;
                }
      .sidenav .closebtn {
          position: absolute;
          top: 0;
          right: 20px;
          font-size: 36px;
          margin-left: 50px;
                }
      @media screen and (max-height: 450px) {
          .sidenav {padding-top: 15px;}
          .sidenav a {font-size: 18px;}
      }
      
       .linear{
           width:100px;
           height:100px;
           border-radius:50px;
       }


      .table {
          text-align: center;
          margin-top: -30px;
          z-index:50px;
      }
      .iframe{
          
          z-index: -100;
          
         }
        </style>
</head>

<body>
  <div id="mySidenav" class="sidenav">
     <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
     
     <img src="__PUBLIC__/img/{$Think.session.vipname_img}" class="linear" />
          </hr>
     <a href="{:U('#')}">{$Think.session.vipname_username}</a>
     <a href="#">N: {$user.vpp_e}  A</a>
     </hr>
     <a href="#" id="buy">MA</a>
     </hr>
     <a href="{:U('/admin/img')}">图片</a>
     </hr>
     <a href="{:U('Public/logout')}">退出</a>
     </hr>
  </div>
  <div class="fy">
  <span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776;</span>
  </div>
      <br>
    <div class="table">
      <iframe frameborder="0" src="https://www.baidu.com" width="100%" height="100%" >       
      </iframe>
    </div>
 </div>
</body>
</html>

怎么使用margin-top:-50px; 不遮住左上方菜单按钮
或者使用其他实现,求实例


<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link href="__PUBLIC__/css/css.css" rel="stylesheet">
<title>标题</title>
 
    <script src="__PUBLIC__/static/jquery-2.1.1.min.js"></script>
    <script src="__PUBLIC__/static/layer/layer.js"></script>
        <script type="text/javascript">
            function openNav() {
    document.getElementById("mySidenav").style.width = "98%";
}
function closeNav() {
    document.getElementById("mySidenav").style.width = "0";
}
        </script>
        <style type="text/css">
         
            
            
            
            body {
                font-family: "Lato", sans-serif;
            }
            .sidenav {
                height: 100%;
                width: 0;
                position: fixed;
                z-index: 1;
                top: 0;
                left: 0;
                background-color: #17202A;
                overflow-x: hidden;
                transition: 0.5s;
                padding-top: 60px;
                text-align:center;
                
            }
      .sidenav a {
          padding: 8px 8px 8px 32px;
          text-decoration: none;
          font-size: 25px;
          color: #7B7D7D;
          display: block;
          transition: 0.3s;
                }
      .sidenav a:hover{
          color: #f1f1f1;
                }
      .sidenav .closebtn {
          position: absolute;
          top: 0;
          right: 20px;
          font-size: 36px;
          margin-left: 50px;
                }
      @media screen and (max-height: 450px) {
          .sidenav {padding-top: 15px;}
          .sidenav a {font-size: 18px;}
      }
      
       .linear{
           width:100px;
           height:100px;
           border-radius:50px;
       }
 
 
      .table {
          text-align: center;
          position: absolute;
          top: 0;
          width: 100%;
      }
      .iframe{
          
          z-index: -100;
          
         }
        </style>
</head>
 
<body>
  <div id="mySidenav" class="sidenav">
     <a href="javascript:void(0)" class="closebtn" onclick="closeNav()">&times;</a>
     
     <img src="__PUBLIC__/img/{$Think.session.vipname_img}" class="linear" />
          </hr>
     <a href="{:U('#')}">{$Think.session.vipname_username}</a>
     <a href="#">N: {$user.vpp_e}  A</a>
     </hr>
     <a href="#" id="buy">MA</a>
     </hr>
     <a href="{:U('/admin/img')}">图片</a>
     </hr>
     <a href="{:U('Public/logout')}">退出</a>
     </hr>
  </div>
  <div class="fy">
  <span style="font-size:30px;cursor:pointer" onclick="openNav()">&#9776;</span>
  </div>
      <br>
    <div class="table">
      <iframe frameborder="0" src="https://www.baidu.com" width="100%" height="100%" >       
      </iframe>
    </div>
 </div>
</body>
</html>