Svelte 5: `:nth-of-type(10)` and `:nth-of-type(10n[+1])` (> 1 digit) do not compile

[bwbroersma]

Describe the bug

Valid CSS does not compile.

li:nth-of-type(10) {color: red;} /* breaks */
li:nth-of-type(10n) {color: green;} /* breaks */
li:nth-of-type(10n+1) {color: blue;} /* breaks */
li:nth-of-type(1n+10) {color: yellow;} /* works */

Reproduction

<style>
	li:nth-of-type(10n) {color: red;}
	li:nth-of-type(11) {color: green;}
</style>
<ol>
{#each new Array(12) as x, i}
	<li>{i+1}</li>
{/each}
</ol>

REPL Svelte 5 variant does not compile in v5.0.0-next.26.

gives

Error compiling App.svelte
Expected a valid CSS identifier
line 2 column 16

REPL Svelte 4 variant compiles.

Logs

-

System Info

REPL - v5.0.0-next.26

Severity

blocking an upgrade