hang label of aside

aside {
  margin-left: 10em;
  position: relative;
  outline: 1px solid #f0f;
}

aside::before {
  margin-right: 1em;
  display: block;
  position: absolute;
  right: 100%;
  width: 9em;
  content: "NOTE";
  outline: 1px solid #f0f;
}