old_contents: 
  const commonDeclarations = {
    boxSizing: [
      'border-box'
    ],
  
    display: [
      'block',
      'inline-block',
      'inline',
      'table',
      'table-cell',
      'none'
    ],
  
    float: [
      'none',
      'left',
      'right'
    ],
    clear: [
      'none',
      'left',
      'right',
      'both'
    ],
  
    textAlign: [
      'left',
      'center',
      'right',
      'justify'
    ],
  
    fontWeight: [
      'bold',
      'normal'
    ],
  
    textDecoration: [
      'none',
      'underline'
    ],
    whiteSpace: [ 'nowrap' ],
    listStyle: [ 'none' ],
    overflow: [
      'hidden',
      'scroll'
    ],
  
    margin: [ 0 ],
    marginTop: [ 0 ],
    marginRight: [ 0 ],
    marginBottom: [ 0 ],
    marginLeft: [ 0 ],
    padding: [ 0 ],
    paddingTop: [ 0 ],
    paddingRight: [ 0 ],
    paddingBottom: [ 0 ],
    paddingLeft: [ 0 ],
  
    maxWidth: [ '100%' ],
    height: [ 'auto' ],
  
    verticalAlign: [
      'top',
      'middle',
      'bottom',
      'baseline'
    ],
  
    position: [
      'relative',
      'absolute',
      'fixed'
    ],
  
    borderRadius: [ 0 ]
  }
  
  export default commonDeclarations
  
  
new_contents: 
  const commonDeclarations = {
    boxSizing: [
      'border-box'
    ],
  
    display: [
      'block',
      'inline-block',
      'inline',
      'table',
      'table-cell',
      'none'
    ],
  
    float: [
      'none',
      'left',
      'right'
    ],
    clear: [
      'none',
      'left',
      'right',
      'both'
    ],
  
    textAlign: [
      'left',
      'center',
      'right',
      'justify'
    ],
  
    fontWeight: [
      'bold',
      'normal'
    ],
  
    textDecoration: [
      'none',
      'underline'
    ],
    whiteSpace: [ 'nowrap' ],
    listStyle: [ 'none' ],
    overflow: [
      'hidden',
      'scroll'
    ],
  
    margin: [ 0 ],
    marginTop: [ 0 ],
    marginRight: [ 0 ],
    marginBottom: [ 0 ],
    marginLeft: [ 0 ],
    padding: [ 0 ],
    paddingTop: [ 0 ],
    paddingRight: [ 0 ],
    paddingBottom: [ 0 ],
    paddingLeft: [ 0 ],
  
    maxWidth: [ '100%' ],
    height: [ 'auto' ],
  
    verticalAlign: [
      'top',
      'middle',
      'bottom',
      'baseline'
    ],
  
    position: [
      'relative',
      'absolute',
      'fixed'
    ],
  
    borderRadius: [ 0 ],
    
    backgroundSize: [
      'contain',
      'cover'
    ],
    backgroundRepeat: [
      'no-repeat',
      'repeat',
      'repeat-x',
      'repeat-y'
    ],
    backgroundPosition: [
      'top',
      'right',
      'bottom',
      'left',
      'center'
    ]
  }
  
  export default commonDeclarations
  
subject: Add backgrounds to common declarations