title: Subtract element width from body width, and add as margin to element
body: <p>I have an image inside a container. The image should always be at full browser width (100vw). As my layout is responsive, and the container has a fixed width at a certain point (45em), I can't simply use negative margins. So I got an idea, but as a novice I can't seem to achieve it...</p>
  
  <p>This is what I want to do:</p>
  
  <ul>
  <li>Check the body width</li>
  <li>Check the container width</li>
  <li>Subtract the element width from the body width</li>
  <li>Divide this number in two</li>
  <li>Add this number as a negative margin to an element</li>
  </ul>
  
  <p>This is what I got so far...</p>
  
  <pre><code>var bodyWidth = $('body').width(); //Check the body width
  var elemWidth = $('#content').width(); //Check the container width
  var margin = bodyWidth-elemWidth; //Subtract the element width from the body width
  </code></pre>
  
  <p>I still need to divide the number in two, and add this number as a negative margin to an element.</p>
  
  <p>Help is much appreciated.</p>