Embedded CSS gets loaded with every page request, changes cannot be shared across pages, and the content cannot be cached. Thus, it decreases performance, reusability and maintainability. External CSS should be used whenever possible instead.

Noncompliant Code Example

<style type="text/css">
  .mybox {
    color: green;
  }
</style>

Compliant Solution

<link rel="stylesheet" type="text/css" href="mystyles.css"/>