Why isn't the hr element from the 1st to the 3rd hour red as specified in the CSS code below?
hr:nth-of-type(n+1):nth-of-type(-n+3){
background:red;
}
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<hr />
<p>The first paragraph.</p>
<p>The second paragraph.</p>
<p>The third paragraph.</p>
<hr />
<hr />
<hr />
<p>The fourth paragraph.</p>
</body>
</html>