how to make Utteranc.es theme follow archie's?

hello, I am a total beginer in web dev. I want to add comment system named "Utteranc.es" in archie. But I got some problems.

```js

```
my plan is, the theme of utterances follows archie's dark/light mode.
I tried the way like ` theme="github-{{mode}}"` but failed.
But I can not find a way to do it. Any suggestions would be very appreciated!

The issue only provides an Utteranc.es client snippet and does not name an Archie file or test. Start by locating Archie's dark/light-mode entry point and the template that would host the snippet; done means Utteranc.es follows the selected site mode and the behavior is verified in both modes.

Written by the indexing model from the issue text.