HTML Guide for semicolon

Character references must always start with an ampersand (&) and end with a semicolon (;), for example the < character can be referenced as &lt;.

CSS properties need to be separated by semicolons. Check for the missing semicolon between properties.

In the example below, a forgotten semicolon before the content property makes the CSS parser unable to understand the properties:

<style>
nice {
  z-index: auto 
  content: ""; 
  display: block; 
}
</style>

Fix it by including the forgotten semicolon like this:

<style>
nice {
  z-index: auto;
  content: ""; 
  display: block; 
}
</style>