title: Customize ActiveAdmin::FormBuilder (make different partial)
body: <p>I want to use ActiveAdmin::FormBuilder, because I like the way it allows to generate nested models (mostly - its <code>has_many</code> method, which generates nice buttons with inline javascript to easily create &amp; destroy nested objects).</p>
  
  <p>However I want to edit form itself, because the way it looks by default takes too much space.</p>
  
  <p>Does anyone know if there's a good way to customize the form design output, but keep those nested  methods for nested objects?</p>
  
  <p>Here is a code example with comments: </p>
  
  <pre><code>&lt;%= semantic_form_for @item, builder: ActiveAdmin::FormBuilder do |f| %&gt;
  
      &lt;% f.inputs "Item Details" do %&gt;
        &lt;% f.input :keywords %&gt;
        &lt;% f.input :description %&gt;
      &lt;% end %&gt;
  
      &lt;% f.inputs "Features", :id =&gt; "item_features" do %&gt;
        &lt;% f.has_many :features, :header =&gt; "" do |feature| %&gt;
          &lt;!-- all these fields are generated in separate rows, I want to fit them all to one row - so need to add some classes--&gt;
          &lt;% feature.input :name, :label =&gt; "Feature Name" %&gt;
          &lt;% feature.input :value, :label =&gt; "Feature Value" %&gt;
          &lt;% feature.input :_destroy, :as=&gt;:boolean, :required =&gt; false, :label=&gt;'Remove Feature' %&gt;
        &lt;% end %&gt;
      &lt;% end %&gt;
  
      &lt;% f.inputs "Options", :id =&gt; "item_options" do %&gt;
        &lt;% f.has_many :options, :header =&gt; "" do |option| %&gt;
          &lt;!-- same thing here --&gt;
          &lt;% option.input :name, :label =&gt; "Option Name" %&gt;
          &lt;% option.input :_destroy, :as=&gt;:boolean, :required =&gt; false, :label=&gt;'Remove Option' %&gt;
        &lt;% end %&gt;
      &lt;% end %&gt;
  
      &lt;% f.actions %&gt; &lt;!-- here I want to add some classes to each button --&gt;
    &lt;% end %&gt;
  </code></pre>