pseudo-class selector nth-last-of-type alternating three images (Interactive Example)

<!DOCTYPE html>
<title>Example</title>
<style>
	img:nth-last-of-type(3n+1) {
		border: 1em solid tomato;
	}       
	img:nth-last-of-type(3n+2) {
		border: 1em solid limegreen;
	}       
	img:nth-last-of-type(3n+3) {
		border: 1em solid skyblue;
	}       
</style>

<p>Three images:</p>
<img src="/pix/samples/8s.jpg" alt="Sample image">
<img src="/pix/samples/9s.jpg" alt="Sample image">
<img src="/pix/samples/10s.jpg" alt="Sample image">

<p>Three images:</p>
<img src="/pix/samples/11s.jpg" alt="Sample image">
<img src="/pix/samples/8s.jpg" alt="Sample image">
<img src="/pix/samples/9s.jpg" alt="Sample image">

<p>Three images:</p>
<img src="/pix/samples/10s.jpg" alt="Sample image">
<img src="/pix/samples/11s.jpg" alt="Sample image">
<img src="/pix/samples/8s.jpg" alt="Sample image">

<p>Three images:</p>
<img src="/pix/samples/9s.jpg" alt="Sample image">
<img src="/pix/samples/10s.jpg" alt="Sample image">
<img src="/pix/samples/11s.jpg" alt="Sample image">