The component has a parameter named "style" which is set to "wide". You can change the value to "slim" to condense things down a bit. That sample code is actually at the bottom of Doug's post. Here it is again for easy reference:
<#assign message_list_title = text.format("custom.top_five_threads_with_no_replies.title") />
<#assign results_list_size = 5 />
<#assign rest_query = "/search/messages?openresponse=true&sort_by=-topicPostDate&page_size=" + results_list_size />
<div class="lia-panel lia-panel-standard top-five-threads-with-no-replies-wrapper">
<@component id="forums.widget.message-list-panel" title="${message_list_title}" messages="rest_v1:"+rest_query style="slim" numMessages="conv:"+results_list_size />
</div>
