title: Button position changes when I expand the window
body: <p>I am trying to design a webpage where the top division is an image with a transparent button on it.The problem is that each time I minimize the window, the button changes position. Can anyone tell me what the problem is?</p>
  
  <pre><code>&lt;html lang=="en"&gt;
  &lt;meta name="viewport" content="width=device-width, initial-scale=1"&gt;
  
  &lt;head&gt;
    &lt;meta charset="utf-8"&gt;
    &lt;title&gt;Deut65&lt;/title&gt;
    &lt;link href="site.css" rel="stylesheet"&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  
  &lt;ul id="nav"&gt;
    &lt;img id="logo" src="logo.png"&gt;&lt;/img&gt;
    &lt;li&gt;&lt;a href="#home"&gt;Home&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#editor"&gt;Editor&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#about"&gt;About&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;
  
  
     &lt;div id="image-div"&gt;
        &lt;img id="top-image"src="fotoDeut65.jpeg"&gt;
        &lt;button id="image-button"&gt;Button&lt;/button&gt;
     &lt;/div&gt;
  
  
  &lt;style&gt;
  
  
   #image-div{ 
    top: -50%; 
    left: -50%; 
    width: 100%; 
    height: 100%;
   }
  
  #top-image{
    position: absolute;  
    top: 0; 
    left: 0; 
    right: 0; 
    bottom: 0; 
    margin: auto; 
    min-width: 100%;
    min-height: 100%;
    width: 400px;
    height: auto;
  }
  
  #image-button{
      position: relative;
      z-index: 1;
    margin-left: auto;
    margin-right: auto;
     top: 191px;
      left: 420px;
      right: -420px;
      bottom: -191px;
  }
  &lt;/style&gt;
  
  
  
  
  &lt;!--until here--&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>