Edit in JSFiddle

<style>
.foo{
  color: blue;
}
</style>
<!--
// code in css-file:
.foo{
  color: red;
  background: black;
}
-->
<link rel="stylesheet" href="https://b6158d9f33d13ac0ef5aea735ac6b92c9ce30c2f.googledrive.com/host/0B61sAlRH-x4sUkM1d0VnS3dqbzg/style-vs-link.css">
<style>
.foo{
  background: yellow;
}
</style>

<div class="foo">
  Etiam ultricies nisi vel augue
</div>