title: div background image zoom issue
body: <p>I have a div with background image which contains 3 colors of the same icon</p>
  
  <p><img src="https://i.stack.imgur.com/38095.png" alt="icon"><br>
  I shift the icon (background-position: top/center/bottom) according to what page is user viewing: <img src="https://i.stack.imgur.com/RUB54.png" alt="div with icon"></p>
  
  <p>All works fine utill I zoom the page (ctrl + mousewheel) - than the background image seems to shift one pixel up or something, so i can see one-pixel line of the other icon at the bottom of my wrapper div: <img src="https://i.stack.imgur.com/CIylt.png" alt="zoomed"></p>
  
  <p>Screens are from IE but it looks even more broken on iPad...<br>
  Any thoughts about what is causing this and how to fix it? </p>
  
  <p><img src="https://i.stack.imgur.com/vvvGt.png" alt="enter image description here"></p>