Hugo-theme-stack/layouts/partials/comments/provider/utterances.html

<script src="https://utteranc.es/client.js" 
        repo="{{ .Site.Params.comments.utterances.repo }}"
        issue-term="{{ .Site.Params.comments.utterances.issueTerm }}"
        theme="{{ .Site.Params.comments.utterances.theme }}" 
        {{ with .Site.Params.comments.utterances.label }}
        label="{{ . }}"
        {{ end }}
        crossorigin="anonymous" 
        async>
</script>

<style>
    .utterances {
        max-width: unset;
    }
</style>

<script>
    window.addEventListener('onColorSchemeChange', (e) => {
        let utterances = document.querySelector('.utterances iframe');
        if (utterances) {
            utterances.contentWindow.postMessage(
                {
                    type: 'set-theme',
                    theme: `github-${e.detail}`
                },
                'https://utteranc.es'
            );
        }
    })
</script>