CSS stuff

index.html

<!-- 
  even though the "blue" comes later in the list of classes,
  but CSS rules of precedence actually depends of the order of
  classes in the stylesheet
-->
<span class="red blue">
  so I'm red
</span>

styles.css

/* CSS */

.blue { color: blue; } 

.red { color: red: } /* this is why the text is red */