title: React Native writing to Styles
body: <p>quick question.
  Is it possible to change the value of an already defined style? such as:
  styles.container.backgroundColor?</p>
  
  <p>I get an 'Attempt to write to readonly property' error but this seems crazy that I couldn't change background colors on the fly. Is there a best practice way of doing this that I've missed?</p>
  
  <p>Much appreciated,
  a.</p>