how to apply id 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: CSS how to select ID

#id-selector-name{
  font-size: 20px;
}

.class-selector-name{
  color: green;
}