amdest

// https://github.com/twitter/bootstrap/issues/675#issuecomment-6184243

$('#feedback-modal').modal({
        backdrop: true,
        keyboard: true
    }).css({
       'width': function () { 
           return ($(document).width() * .9) + 'px';  
       },
       'margin-left': function () { 

amdest

<nav id='<%= dom_id %>' class='<%= css %>'>
  <ul>
    <%= render :partial => '/refinery/menu_branch', :collection => roots,
               :locals => {
                 :hide_children => hide_children,
                 :sibling_count => (roots.length - 1),
                 :apply_css => true #if you don't care about class='first' class='last' or class='selected' set apply_css to false for speed.
               } -%>
  </ul>
</nav>