title: How to calculate font-size through his parent in SASS?
body: <p>I have several heading in my scss file:</p>
  
  <pre><code>h1{font-size:18px}
  h2{font-size:16px}
  h3{font-size:12px}
  </code></pre>
  
  <p>and in my my index.html i've got this:</p>
  
  <pre><code>&lt;h1&gt;Heading &lt;span&gt;Secondary text&lt;/span&gt;&lt;/h1&gt;
  &lt;h2&gt;Heading &lt;span&gt;Secondary text&lt;/span&gt;&lt;/h2&gt;
  &lt;h3&gt;Heading &lt;span&gt;Secondary text&lt;/span&gt;&lt;/h3&gt;
  </code></pre>
  
  <p>I would like to calculate the font-size of the SPAN tag, lats say.. font-size equal minus 2px to the heading that contains him?</p>