title: Setting div width to 100% minus certain amount of px
body: <p>Have been searching the net for the past hours to find a solution to this, but couldn't find it, so here I am. </p>
  
  <p>I need the width of the <code>div</code> to be <code>100%</code> minus the width of the <code>left div</code>. </p>
  
  <p>So that the <code>div</code> to the left of it stays the same width (390px) but the other <code>div</code> adjusts its size depending on the resolution . I have found the solution where it has a fixed width <code>div</code> on both sides, but just cant figure this out. </p>
  
  <p><img src="https://i.stack.imgur.com/uXBA8.png" alt="enter image description here"></p>