.green { background-color: lime; }
.white { background-color: transparent ! important; }
div.stub > p + p { background-color: red; }

 <div class="stub">
  <p class="green">This paragraph should have a green background.</p>
  <p class="white">But this one should be unstyled.</p>
  <p class="white">And this one should also be unstyled.</p>
  <address class="green">This address is only here to fill some space between two paragraphs and should have a green background.</address>
  <p class="green">This paragraph should have a green background too.</p>
 </div>