function buildRoot (el) {
  let rootCSS = el.styles

  if (typeof el.width !== 'undefined' && el.width !== null) {
    rootCSS = {...rootCSS, width: isNaN(el.width) ? el.width : (el.width + 'px')}
  }
  if (typeof el.height !== 'undefined' && el.height !== null) {
    rootCSS = {...rootCSS, height: isNaN(el.height) ? el.height : (el.height + 'px')}
  }

  return rootCSS
}
Creates the CSS for the root element