Use the opacity property to add transparency to the background of an element. You can try to run the following code to work.
Example
<!DOCTYPE html>
<html>
<head>
<style>
div {
background-color: #808000;
padding: 20px;
}
div.one {
opacity: 0.2;
filter: alpha(opacity=20);
}
div.two {
opacity: 0.5;
filter: alpha(opacity=50);
}
</style>
</head>
<body>
<h1>Heading</h1>
<p>Check transparency in the below section:</p>
<div class = "one">
<p>opacity 0.2</p>
</div>
<div class = "two">
<p>opacity 0.5</p>
</div>
<div>
<p>opacity 1</p>
</div>
</body>
</html>