Prime numbers

This is my sieve of Eratosthenes in CSS. How fast is it?

<style>

.numbers li{
	display: inline-block;
	counter-increment: numbers;
	color: grey;
	text-align:center;
	padding: 0.5vw;
	width: 30px;
	height: 30px;
	line-height: 30px;
	border: 1px solid red;
	border-radius: 50%;
	color: red;
}

.numbers li::before{
	content: counter(numbers);
}

.numbers li:first-child,
.numbers li:nth-child(2n+2),
.numbers li:nth-child(3n+6),
.numbers li:nth-child(5n+10),
.numbers li:nth-child(7n+14)
{
	color: #aaa;
	border-color: transparent;
}

</style>


<ul class="numbers">
  <li></li>
  <li></li>
  <li></li>
   ...
  <li></li>
  <li></li>
  <li></li>
</ul>