app/views/shared/_search_form.html.erb
<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>