<form action="${portal_url}/@@search">
  <label for="main-search" class="visually-hidden">Search</label>
  <input id="main-search" type="text" name="SearchableText" placeholder="Search..." />
  <button class="secondary button" type="submit"><img src="++plone++castle/svg/icon-search.svg" alt="Submit Search"></button>
</form>
