title: Why doesn't the CSS calc() function work for me?
body: <p>I learned about the CSS function calc() and its awesome. I tried to use it like:</p>
  
  <pre class="lang-css prettyprint-override"><code>#abc{width:calc(100%-20px)}
  </code></pre>
  
  <p>But the problem with this function is that it doesn't work. I tested this code IE9 and Safari and it didn't work.</p>
  
  <p>Why doesn't it work?</p>