body {
  transition: background-color .5s, color 0.5s;
  -webkit-transition: background-color 0.5s, color 0.5s;
}

a {
  transition: color .5;
  -webkit-transition: color 0.5s;
}

.mode-switch {
  transition: boder-color .5;
  -webkit-transition: boder-color  0.5s;
}