fohow_admin/app/views/devise/sessions/new.html.erb

<div class="container">

  <%= form_for(resource, :as => resource_name, :url => session_path(resource_name), :html => {:class => "form-signin"}) do |f| %>
      <div class="form-signin-heading">用户登入</div>
      <% if flash[:alert] %>
          <div class="alert alert-error">
            <a class="close" data-dismiss="alert">×</a>
            <div id="flash_alert"><%= flash[:alert] %></div>
          </div>
      <% end -%>
      <%= f.email_field :email, :autofocus => true, :class => "input-block-level", :placeholder => "邮箱" %>
      <br/>
      <%= f.password_field :password, :class => "input-block-level", :placeholder => "密码" %>
      <label class="checkbox">
        <%= f.check_box :remember_me %> <span class="remember_pw">记住密码</span>
      </label>
      <%= f.submit "登入", :class => "btn btn-large btn-primary" %>
  <% end -%>

</div>