code: function setDpi() {
      const dpiO = {};
      const e = document.body.appendChild( document.createElement( 'DIV' ) );
      e.style.width = '1in';
      e.style.padding = '0';
      dpiO.v = e.offsetWidth;
      e.parentNode.removeChild( e );
      dpi = dpiO.v;
  }
docs: Calculates the dots per inch and sets the dpi property