todo {
  display: block;
  max-width: 400px;
  margin: 5% auto;
}
button.todo {
  background-color: #1fadc5;
  border: 1px solid rgba(0,0,0,0.2);
  font-size: 100%;
  color: #fff;
  padding: 0.6em 1.2em;
  border-radius: 3em;
  cursor: pointer;
  margin: 0 0.3em;
  outline: none;
}
button.todo[disabled] {
  background-color: #ddd;
  color: #aaa;
}