title: Padding/margin-inclusive width setting?
body: <p>Basically I have a div that I want at 100% width. However, I also want it to have some padding. But when I add the padding, the width is added to it, meaning that my div now goes off-screen and there's a horizontal scroll bar.</p>
  
  <p>Usually I compensate by just making the div a lower percentage (like 95%, or 90%).</p>
  
  <p>I was wondering if there are any more elegant ways to handle this situation?</p>