I really need help in displaying the drop-down sub-menus correctly in my website as soon as possible. 

The sub-menus in my drop-down menu is **stacking over one another**. 

I want those sub-menus to be displayed vertically. 

How do I fix this?

Here is my code :

```css
div#nav_menu-2{
   float: left!important;
}

div.menu-secondary-container{
   display: block;
    background-color: #f3e6ff;
 background-size: cover;
 margin: 0px;
 padding: 0px;
 overflow: visible;
 position: static;
}

div#nav_menu-2 ul{
    top: 0px;
    margin: 0px;
}

div#nav_menu-2 ul li{
    list-style-type: none;
 /*position: relative;*/
 display: inline-block;
}

div#nav_menu-2 ul li a{
   display: block;
 padding: 14px 16px;
 text-align: center;
 line-height: 30px;
 text-decoration: none;
 font-size: 12pt;
 font-weight: bold;
 color: purple;
 text-transform: uppercase;
}

div#nav_menu-2 ul li a:hover{
 background-color: lightgray;
}

div#nav_menu-2 ul li a:active{
 background-color: hotpink;
}

div#nav_menu-2 ul li a:link{
 color: darkpurple;
}

div#nav_menu-2 ul li a:visited{
 color: lightpurple;
}

.active{
 background-color: dimgray;
}

div#nav_menu-2 ul li li{
   display:none;
   clear: both;
   overflow: auto;
   white-space: nowrap;
}

div#nav_menu-2 ul li:hover ul li{
 display: block;
    position:absolute;

}

div#nav_menu-2 ul li li a{
 background-color: lightgray;
 padding: 14px 16px;
 min-width: 160px;
 display: block;
 text-align: center;
}
```

```html
<div id="nav_menu-2" class="header-widget widget_nav_menu header-widget-1 header-widget-num-1">
<div class="menu-secondary-container">
  <ul id="menu-secondary" class="menu">
    <li id="menu-item-115" class="menu-item menu-item-     type-post_type menu-item-object-page menu-item-has-children menu-item-115">
      <a href="http://localhost/careerdishanepal/services/">Services</a>
      <ul class="sub-menu">
     <li id="menu-item-126" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-126">
          <a href="http://localhost/careerdishanepal/background/">Background</a></li>
 <li id="menu-item-129" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-129">
      <a href="http://localhost/careerdishanepal/market-survey-reports/">Market Survey Reports</a></li>
 <li id="menu-item-131" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-131">
      <a href="http://localhost/careerdishanepal/behind-the-scene/">Behind the scene</a></li>
</ul>
</li>
  <li id="menu-item-116" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-has-children menu-item-116">
    <a href="http://localhost/careerdishanepal/about-us/">About Us</a>
<ul class="sub-menu">
 <li id="menu-item-128" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-128">
      <a href="http://localhost/careerdishanepal/goals-and-objectives/">Goals and Objectives</a></li>
 <li id="menu-item-130" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-130">
      <a href="http://localhost/careerdishanepal/social-need-assessment-study/">Social Need Assessment Study</a></li>
</ul>
</li>
<li id="menu-item-117" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-117">
  <a href="http://localhost/careerdishanepal/contact/">Contact</a></li>
</ul>
  </div>
</div>
```