title: centering content while having a side-bar on the left
body: <p>I have a fixed nav-bar on the top and a fixed side-bar on the left.
  The content should be in the middle. <code>margin: auto</code> in this case with the side-bar on the left doesn't do the trick.</p>
  <p>The problem is, that <code>margin: auto</code> does not consider the width of the side-bar.</p>
  <p>The div, which should contain the content and must be centered has more space on the right side, than on the left side (the side-bar is on the left side)</p>
  <p><img src="https://i.stack.imgur.com/cRJAX.png" alt="image" />.</p>
  <p>There is also the link to the code: <a href="https://codepen.io/arnameti/pen/RwpmoQJ" rel="nofollow noreferrer">https://codepen.io/arnameti/pen/RwpmoQJ</a></p>
  <p>Then i tried with <code>width: calc(auto - 'width of side-nav')</code>, but i realized that the calc-function doesn't acceppt <code>auto</code> as a value.</p>
  <p>I've tried a lot to solve by puting a <em><strong>div</strong></em> around and using <em><strong>flex-box</strong></em>.
  Unfortunately, i don't get the desired result and i am now in the situation where i need help or advice.</p>