title: How to have a collasped drop down list in rails simple_form
body: <p>In my app, there are two models: rfq and standard. Their relationship is many-to-many. In rfq creating screen, the code below displays a list of available for selection in drop down list:</p>
  
  <pre><code>&lt;%= simple_form_for @rfq do |f| %&gt;    
  &lt;%= f.association :standards, :collection =&gt; Standard.active_std.all(:order =&gt; 'name'), :label_method =&gt; :name, :value_method =&gt; :id %&gt; 
  &lt;% end %&gt;
  </code></pre>
  
  <p>The problem is that the list is not collapsed, which means there are multiple standards displayed in a multi-line boxes. How can I reduce the box to one line only?</p>
  
  <p>Thanks.</p>
  
  <p>UPDATED: here is the screen shot of multiple line list box:
  <img src="https://i.stack.imgur.com/YKTT3.jpg" alt="enter image description here"></p>