internal css

CSS
<!DOCTYPE html>
<html>
<head>
<style>

 body {background-color: powderblue;}
h1   {color: blue;}
p    {color: red;}

</style>
</head>
<body>

<h1>This is a 
 heading</h1>
<p>This is a paragraph.</p>

</body>
</html>   <!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" 
  href="mystyle.css">
</head>
<body>

<h1>This is a heading</h1>

  <p>This is a paragraph.</p>

</body>
</html> <html>
  <head>
    <link rel="stylesheet" type="text/css" href="mystyle.css"></link>
  </head>

  <body><link rel="stylesheet" type="text/css" href="style.css"> <link rel="stylesheet" type="text/css" href="mystyle.css"><!DOCTYPE html>
<html>
<head>
<style>
body {background-color: powderblue;}
h1   {color: blue;}
p    {color: red;}
</style>
</head>
<body>

<h1>This is a heading</h1>
<p>This is a paragraph.</p>

</body>
</html>
Source