searxng/searx/templates/simple/simple_search.html

<form id="search" method="{{ method or 'POST' }}" action="{{ url_for('search') }}" role="search">
  <div id="search_header">
    <div class="search_box">
      <input id="q" autofocus name="q" type="text" placeholder="{{ _('Search for...') }}" autocomplete="off" spellcheck="false" dir="auto" value="{{ q or '' }}">
      <button id="clear_search" type="reset" aria-label="{{ _('clear') }}"><span class="hide_if_nojs">{{ icon_big('close') }}</span><span class="show_if_nojs">{{ _('clear') }}</span></button>
      <button id="send_search" type="submit" aria-label="{{ _('search') }}"><span class="hide_if_nojs">{{ icon_big('search-outline') }}</span><span class="show_if_nojs">{{ _('search') }}</span></button>
    </div>
  </div>
  {% for category in selected_categories %}
  <input type="hidden" name="category_{{ category }}" value="1" >
  {% endfor %}
  <input type="hidden" name="language" value="{{ current_language }}" >
  <input type="hidden" name="time_range" value="{{ time_range }}" >
  <input type="hidden" name="safesearch" value="{{ safesearch }}" >
  <input type="hidden" name="theme" value="{{ theme }}" >
  {% if timeout_limit %}<input type="hidden" name="timeout_limit" value="{{ timeout_limit|e }}" >{% endif %}
</form>