How add Vertical Menu in left center of default layout view

Question

Problem

I have vertical menu bar jquery css and i need to add to layout view(master page) in visual studio 2015

so that How to do that .

vertical menu bar jquery css code

This menu working without any problem but

my problem how to put menu in left side in layout view

css

StyleSheet1.css

 

ul,
li,
a {
  padding: 0px;
  margin: 0px;
}

#nav1 a {
  color: #FFFFFF;
}

#nav1 li ul li a:hover {
  background-color: #394963;
}

div ul li ul {
  background-color: #4a5b78;
  list-style: none
}

#nav1 > li > a {
  background-color: #343434;
  padding: 16px 18px;
  text-decoration: none;
  display: block;
  border-bottom: 2px solid #212121;
  background: linear-gradient(top, #343434, #111111);
}

#nav1 li ul li a {
  padding: 10px 0;
  padding-left: 30px;
  text-decoration: none;
  display: block;
}

div {
  background-color: #000000;
  background-color: #343434;
  width: 280px;
}
/* Hide Dropdowns by Default */
#nav1 li ul {
  display: none;
}
jquery

$(document).ready(function() {
  $("#nav1 li").hover(
    function() {
      $(this).find('ul').slideDown();
    },
    function() {
      $(this).find('ul').slideUp();
    });
});


HTML

<div id="container">
  <ul id="nav1">
    <li><a href="#">Menu Heading 1</a>
    <ul>
      <li><a href="#">Stage1</a></li>
      <li><a href="#">Stage2</a></li>
      <li><a href="#">Stage3</a></li>
      <li><a href="#">Stage4</a></li>
    </ul>
    </li>
    <li><a href="#">Menu Heading 2</a>
      <ul>
      <li><a href="#">Stage1</a></li>
      <li><a href="#">Stage2</a></li>
      <li><a href="#">Stage3</a></li>
      <li><a href="#">Stage4</a></li>
    </ul>
    </li>
</ul>
<div>

 

my layout view

Layout = "~/Views/Shared/_Layout.cshtml";

default _Layout found in visual studio 2015 without any customization

I do every thing but design come corrupted

actually i need menu in left center side vertically

and not change main design of default layout

because after i apply menu it change main design

see link below

http://www.mediafire.com/view/5z34m3hp9lfjst2/corrupt_design.jpg