i want to blur the background image of this html code using css3 filter and please provide explanation.
<!DOCTYPE html>
<html>
<head>
<title>Student-login</title>
<link href='http://fonts.googleapis.com/css?family=Slabo+27px' rel='stylesheet' type='text/css'>
<style>
body{
background-image: url("background.jpg");
background-size: cover;
background-repeat: no-repeat;
background-position: center;
background-attachment: fixed;
}
</style>
</head>
<body>
<div class="main-form">
<h1>Hello</h1>
</div>
</body>
</html>
But the content in this will not get blurred.