title: Why top:0 with position:absolute not working if another element has margin-top here?
body: <p>Why <code>top:0</code> with <code>position:absolute</code> not working here? </p>
  
  <p>I want to mention that in this condition I don't have control on any other element other than <code>.heatmap</code></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>body {
    position: relative;
    margin: 0;
    padding: 0
  }
  
  .section1 {
    margin-top: 107px;
    border: 1px solid green
  }
  
  .heatmap {
    z-index: 2147483642;
    top: 0px;
    left: 0px;
    position: absolute;
    width: 1425px;
    height: 1110px;
    opacity: 0.7;
    background: red
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="section1"&gt;something&lt;/div&gt;
  
  &lt;div class="heatmap"&gt;hamara heatmap&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p><a href="https://i.stack.imgur.com/Zi9WB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Zi9WB.png" alt="enter image description here"></a></p>