function bgimgOffset(){
  if (!/webkit/.test(navigator.userAgent.toLowerCase())) return;

  getElement = document.getElementsByTagName('html')[0];
  if (document.width % 2 == 0) {
    getElement.style.width = 'auto';
  }

  else{
    getElement.style.width = document.width-1 + 'px';
  }
}

window.onresize = bgimgOffset;