title: retina display image dimentions
body: <p>I have created icons of 2 sized <em>40px X 40px</em> and <em>80px X 80px</em> for normal display and retina display respectively.</p>
  
  <p>what is the proper way to use these 2 sizes of icons?</p>
  
  <p>I mean should i change the dimensions of element for retina version to 80px X 80px or use background-size property to fit the large icons in 40px X 40px size?</p>