Check out example codes for "css styling". It will help you in understanding the concepts better.

Code Example 1

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

Code Example 2

Three ways to add CSS to the body of html:
	1)External CSS
	2)Internal CSS
	3)Inline CSS

1) Externally:  
    Type your css code in a file. Remember you file name.
	Then,
<head>
	<link rel="stylesheet" type="text/css" href="FileName.css" >
</head>

2) Internally:
	Type your cSS in the html file itself. (It is not preffered until
	little CSS code is to be added). This can be done by style tag.
	Example:
	<head>
	<style>
	h1 {
      text-color:red;
      text-size: 0.8em;
    }
    </style>
	</head>

3) Inline:
	This method is not used by developers as it is very lengthy and
	maintaining code becomes difficult.
	Example:
   <h1 style="color:blue;text-align:center;">Header file</h1>

Code Example 3

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

Code Example 4

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

Code Example 5

<p style="color: blue; font-size: 46px;">

Code Example 6

<style>
#panel{
      height: 60%;
      margin-top: 7%;
      margin-left: 10%;
      margin-right: 10%;
      font-family: myriad-pro, sans-serif;
      font-style: normal;
      font-weight: 300;
    }
</style>

Learn ReactJs, React Native from akashmittal.com