<ol>
  <li id="one"> One </li>
  <li class="even"> Two </li>
  <li> Three </li>
  <li class="even"> Four </li>
  <li> Five </li>
</ol>
body {
  font-size: 1.5rem;
}
.even {
  background-color: yellow;
}
#one {
  background-color: green;
}

External CSS

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External JavaScript

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