xmpp.chapril.org-conversejs/src/templates/message.html

<div class="chat-message {{{extra_classes}}}" data-isodate="{{{isodate}}}" data-msgid="{{{msgid}}}">
    <span class="chat-msg-author chat-msg-{{{sender}}}">{{{time}}} {{{username}}}:&nbsp;</span>
    <span class="chat-msg-content"><!-- message gets added here via renderMessage --></span>
</div>