How to add CSS class to simple_form_for collection fields
<%= f.input :answer, as: :radio_buttons, :required => true, :label => false, collection: ([[image_tag(q.optiona),'a'] , [image_tag(q.optionb),'b'], [image_tag(q.optionc),'c'], [image_tag(q.optiond), 'd']]), wrapper: :vertical_radio_and_checkboxes, :input_html => {:class => "img img-thumbnail", :width => 304, :height => 236} %>
The above code is displaying images in its actual size, I want show the images in thumbnails.
Thanks in advance.