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

Code Example 1

/*put a # infront of the id*/
/*<section id="example"></section>*/
#example{
	margin: auto;
}

Code Example 2

<p class="haut">
<a href="#haut">Haut de page</a>
</p>

Code Example 3

<style>
  #selector {
  color: red;
}
/* # is id selector */
</style>


<div id="selector">
<p>This is an id</p>
</div>

Learn ReactJs, React Native from akashmittal.com