<div id="search_form" class="search-form-header">
  <h1 class="show-for-sr"><%= t("shared.outline.searcher") %></h1>
  <%= form_tag search_path, method: :get do %>
    <div class="input-group">
      <label for="search_text" class="show-for-sr"><%= t("#{i18n_namespace}.title") %></label>
      <input type="text" name="search" placeholder='<%= t("#{i18n_namespace}.placeholder") %>' class="input-group-field" value="<%= params[:search] %>" id="search_text">
      <div class="input-group-button">
        <button type="submit" class="button" title="<%= t("#{i18n_namespace}.button") %>">
          <span class="show-for-sr"><%= t("#{i18n_namespace}.button") %></span>
          <span class="icon-search"></span>
        </button>
      </div>
    </div>
  <% end %>
</div>

<div id="search_form" class="search-form-header">
  <h1 class="show-for-sr"><%= t("shared.outline.searcher") %></h1>
  <%= form_tag search_path, method: :get do %>
    <div class="input-group">
      <label for="search_text">
        <span class="show-for-sr"><%= t("#{i18n_namespace}.title") %></span>
        <input type="text" name="search" placeholder="<%= t("#{i18n_namespace}.placeholder") %>"
                                         class="input-group-field"
                                         value="<%= params[:search] %>" id="search_text">
      </label>
      <div class="input-group-button">
        <button type="submit" class="button" title="<%= t("#{i18n_namespace}.button") %>">
          <span class="show-for-sr"><%= t("#{i18n_namespace}.button") %></span>
          <span class="icon-search"></span>
        </button>
      </div>
    </div>
  <% end %>
</div>

Change label for search text
Change label for search text

Label wraps input field to prevent error on missing label (hidden by CSS).
