css link

1.
<link rel="stylesheet" type="text/css" href="styles.css" />

2.
<style type="text/css">
  h1, h2 {
    font: arial,sans-serif;
  }
</style>

3.
<style type="text/css">
  @import url(standardstyles.css);
</style>

4.
<div style="color: red">this block is red.</div> [Inline Style]