Set the width of the new div to 200px, the set the left margin of the content div to 200px.
This works perfectly however I do have one more question. How would one go about and aligning this div and it's content at the top in CSS Sculptor, so it is at the same horizontal level as the text in the div on the right (H1 Main Content and so on)? Because now it stays to the left and below the whole content div.
See the screenshot:
I assume you mean CSS Sculptor? Or am I missing something?:-).