<div class="padding10 shadow">
  <span class="sub-header">Latest Posts</span>
  <ul class="unstyled-list">
    {% for item in site.posts | limit: 5 %}
    <li class="margin10 no-margin-left no-margin-right"><a href="{{ item.url }}">{{ item.title }}</a></li>
    {% endfor %}
  </ul>
</div>

<nav class="padding10 shadow">
  <span class="sub-header">Latest Posts</span>
  <ul class="unstyled-list">
    {% for item in site.posts | limit: 5 %}
    <li class="margin10 no-margin-left no-margin-right"><a href="{{ item.url }}">{{ item.title }}</a></li>
    {% endfor %}
  </ul>
</nav>

Use <nav> for "Latest Posts" box
Use <nav> for "Latest Posts" box
