ikiwiki-theme-bootstrap/templates/googleform.tmpl

<form method="get" action="https://www.google.com/search" id="searchform">
 <div>
  <input name="sitesearch" value="<TMPL_VAR URL>" type="hidden" />
  <input name="q" value="" id="searchbox" size="16" maxlength="255" type="text"
  <TMPL_IF HTML5>placeholder="search"</TMPL_IF> />
 </div>
</form>