Check out example codes for "how to link external css to html". It will help you in understanding the concepts better.

Code Example 1

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

<h1>This is a heading</h1>

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

</body>
</html>

Code Example 2

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

Code Example 3

<link rel=“stylesheet” type=“text/css” href=“style.css” />

Code Example 4

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

Code Example 5

<link rel="stylesheet" href="PathToYourFile.css">

Code Example 6

<head>
	<link rel='stylesheet' href='style.css'>
</head>

Learn ReactJs, React Native from akashmittal.com