<ul>
  <li>
    <input id="red" value="Red">
  </li>
  <li>
    <input id="blue" value="Blue">
  </li>
  <li>
    <input id="yellow" value="Yellow">
  </li>
</ul>

#red:focus {
  background-color: red;
}

#blue:focus {
  background-color: blue;
}

#yellow:focus {
  background-color: yellow;
}