SlideDown event not worked in IE Browser(Version 7)

I made a site but there something wrong in IE7 I have a navigation and when I click on a li-element all the li's slideup and the matching div slidesdown.

This works in all the browsers except IE7

Does anyone know what I need to do to fix this? cause the min-width: 0 doesn't work and I have to use position: relative

The slideup works but the slidedown doesn't.

This is what I have...

var $j = jQuery.noConflict();

$j(function() {
  $j('ul#menus li a').click(
    function() {
      $j('#menu-container .post').slideUp();
      $j('#menu-container #post-' + $j(this).attr('class')).slideDown();
    });
});

/* Menu */

#menu-container {
  display: table;
  margin: 0px auto;
  padding-top: 50px;
  width: 500px;
  text-align: center;
}

#menu-container .post {
  display: none;
  margin: 25px auto 50px;
  width: 575px;
  min-width: 0;
}

#menu-container .first_item {
  display: block;
}

#menu-container h2 {
  margin-bottom: 20px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<ul id="menus">
  <li class="post-1 post type-post hentry category-menus" id="post-1">
    <h2><a href="#" rel="bookmark" title="Permanent Link to menu01" class="1">menu01</a></h2>
  </li>

  <li class="post-11 post type-post hentry category-menus" id="post-11">
    <h2><a href="#" rel="bookmark" title="Permanent Link to menu02" class="11">menu02</a></h2>
  </li>

  <开发者_开发知识库;li class="post-59 post type-post hentry category-menus" id="post-59">
    <h2><a href="#" rel="bookmark" title="Permanent Link to menu03" class="59">menu03</a></h2>
  </li>
</ul>

<div id="menu-container">
  <div class="post-1 post type-post hentry category-menus first_item" id="post-1">
    Content
  </div>

  <div class="post-11 post type-post hentry category-menus" id="post-11">
    Content
  </div>

  <div class="post-59 post type-post hentry category-menus" id="post-59">
    Content
  </div>
</div>
<!-- end #menu-container-->

Classes can not be numbers. Try changing your classes to words and see if that works.

class="title_11"