title: How to make vertical space between div tags?
body: <p>I have three div tags and i want to make space between the div tags vertically and also want my first div tag as a fixed one.</p>
  
  <p>When i set my first div position as <em>not a fixed</em> one, i can <em>able to make vertical space</em>.</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;div&lt;/title&gt;
  &lt;/head&gt;
  &lt;body style="margin: 0; padding: 0;"&gt;
  &lt;div style="width:100%; background-color:Lime;"&gt;
  &lt;div style="width:100%; height:10%; background-color:Blue;"&gt;
  a
  &lt;/div&gt;
  &lt;div style="width:70%; height:100%; background-color:Gray; margin: auto; margin-top: 2em; margin-bottom: 2em;"&gt;
  b
  &lt;/div&gt;
  &lt;div style="width:100%; height:5%; background-color:Aqua;"&gt;
  c
  &lt;/div&gt;        
  &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>When i change my <em>"div a"</em> position as <em>fixed</em> , both <em>"div a" and "div b"</em> came down from the margin-top: 2em.</p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  &lt;title&gt;div&lt;/title&gt;
  &lt;/head&gt;
  &lt;body style="margin: 0; padding: 0;"&gt;
  &lt;div style="width:100%; background-color:Lime;"&gt;
  &lt;div style="width:100%; height:10%; background-color:Blue; position: fixed;"&gt;
  a
  &lt;/div&gt;
  &lt;div style="width:70%; height:100%; background-color:Gray; margin: auto; margin-top: 2em; margin-bottom: 2em;"&gt;
  b
  &lt;/div&gt;
  &lt;div style="width:100%; height:5%; background-color:Aqua;"&gt;
  c
  &lt;/div&gt;        
  &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Please help me to make my <em>"div a"</em> as <em>fixed</em> and to make <em>space</em> between <em>"div a and b"</em>.</p>