How to make two elements intact on zoom level change?

I have a simple tag with a banner and a border at the bottom. How can I stop sliding these two elements on zooming? I was looking for a way to get the two elements intact on zoom in and out. Even after a few hours of search, i couldn't get the desired output. I tried this and one more post which says to change from px to em.

My html tag:

<head>    
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" type="text/css" href="style/style.css" />  
</head>
<body> 
    <div id="header">            
      <img class="logo" src="./style/logo.jpg" width= 895 height= 160">         
    </div>
  <div id="container-border">           
  </div>
</body>

css:

 #header
{ padding:0 20px;
  display:block;
  margin:0 auto;
  background: #D6D6D6 url(background.jpg) repeat-x;
  height: 205px;
  width: 1500px;
  position: center;
}


  #container-border {  
  width: 1538px;
  height:900px;
  margin-left:260px;
  border-color: black;
  border-width: 1px;
  border-style: solid;  
}

Solution

You first need to wrap the content in a containing DIV

HTML

  <div class="site-content">
      <div id="header">            
        <img class="logo" src="./style/logo.jpg" width= 895 height="160">         
      </div>
    <div id="container-border">           
    </div>
  </div>

Note the new DIV .site-content. This is where you would center the website content and control the website contents width.

Here's my codepen: https://codepen.io/arlcode/pen/aRpWZo

I would also recommend not using static width/height for mobile dynamic purpose. You're also going to want to use classes more then ID's because ID's are specific but classes allow you to manipulate multiple DIVs at once.