title: How to set width of a <hr/> in CSS to X number of pixels less than the width:auto?
body: <p>I have a nav with some <code>&lt;hr/&gt;</code> elements. Preferably in pure CSS (3?), how would set the width of the horizontal rules to auto minus X number of pixels?</p>
  
  <p><sub>This does not duplicate <a href="https://stackoverflow.com/questions/12878354/how-to-increase-an-widthauto-divs-width-by-x-pixels-using-pure-css">this question</a>, because it is for what would equate to negative padding, which is impossible.</sub></p>