title: Doubt in css selector > [#id (.class1 or .class2)]
body: <p>I think that it should exist a better way of doing this...</p>
  
  <p>I'm using the follow css selector</p>
  
  <pre><code>#book_form .ano_chegada, #book_form .ano_partida {...}
  </code></pre>
  
  <p>Html:</p>
  
  <pre><code>&lt;form id="book_form"&gt;
  &lt;input class='ano_chegada' .../&gt;
  &lt;input class='ano_partida' .../&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>I really don't like to repeat the form id twice. Is it strictly necessary? 
  I know that it should work without the second id (#book_form) but it will select all the elements which share the same class (.ano_partida), right?</p>
  
  <p>Thank you =) (Obrigado, in portuguese)</p>
  
  <p>Cheers from Portugal</p>