%nav#site
  .go_to_content
    %a(href="#contents") Aller au contenu
    %a(href="#sidebar") Aller au menu
  %ul
    %li= link_to "Accueil", '/'
    %li= link_to "Dépêches", '/news'
    %li= link_to "Journaux", '/journaux'
    %li= link_to "Forums", '/forums'
    %li= link_to "Sondages", '/sondages'
    %li= link_to "Wiki", '/wiki'
    %li= link_to "Suivi", '/suivi'
    %li= link_to "Plan", '/plan'
  = form_tag '/recherche', :method => :get, :target => "_blank" do
    <label for="query" id="label_query">Recherche :</label>
    <input id="query" name="q" type="search" placeholder="Entrer un mot-clé" />
    = submit_tag "Rechercher", :name => nil

%nav#site
  .go_to_content
    %a(href="#contents") Aller au contenu
    %a(href="#sidebar") Aller au menu
  %ul
    %li= link_to "Accueil", '/'
    %li= link_to "Dépêches", '/news'
    %li= link_to "Journaux", '/journaux'
    %li= link_to "Forums", '/forums'
    %li= link_to "Sondages", '/sondages'
    %li= link_to "Wiki", '/wiki'
    %li= link_to "Suivi", '/suivi'
    %li= link_to "Plan", '/plan'
  = form_tag '/recherche', :method => :get, :target => "_blank" do
    <label for="query" id="label_query">Recherche :</label>
    <input id="query" name="q" type="search" placeholder="Entrer un mot-clé" />
    = submit_tag "Rechercher", :name => nil, :id => "search_submit"

Add an id to the search button
Add an id to the search button
