title: Defining variables in SVG
body: <p>I currently have a line filled in SVG like this:</p>
  
  <pre><code>&lt;path d="M 0   45
           L 100 45
           L 100 55
           L 0   55
           Z" fill="gray" /&gt;
  </code></pre>
  
  <p>I would like to define the thickness as a variable instead of hardcoding so that the definition is something along the lines of:</p>
  
  <pre><code>&lt;path d="M 0   50 - t
           L 100 50 - t
           L 100 50 + t
           L 0   50 + t
           Z" fill="gray" /&gt;
  </code></pre>
  
  <p>with <code>t = 5</code>.</p>
  
  <p>Is this possible in a SVG document?</p>