text: # Bubble coloring button
  
  See demo on Codepen: https://codepen.io/comehope/pen/eKqZjy
  
  Watch interactive video on Scrimba: https://scrimba.com/p/pEgDAM/ceBEytp
  
  Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000015560736
  
  Inspired by: Nikolay Talanov https://codepen.io/suez/pen/aOgMxy
  