In order to make your message format intact and larger, please, replace your codes with these:
digest_html:
<n.trim.truncate. size="300">
<n.current_node.node_message_as_html/>
</n.trim.truncate.>
digest_text:
<n.trim.truncate. size="300">
<n.current_node.message.as_text/>
</n.trim.truncate.>