how to specify the id of an element in css code example

Example 1: how to call an id in css

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


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

Example 2: div id css

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