title: Basic CSS selector syntax, combining multiple ids and classes
body: <p>I want to be able to select any of the four individual spans below by their id and class (and nothing else) but I can't seem to find the right syntax... <code>#id1 .class2</code> and <code>#id2 .class2</code> select the two right hand elements OK but <code>#id1 .class1</code> and <code>#id2 .class1</code> seem to select both elements where I'd expect them to select only the first span in the p.</p>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
          &lt;style&gt;
              #id1 .class1{ background: red; }
          &lt;/style&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;p id="id1"&gt;
              &lt;span class="class1"&gt;one&lt;span&gt; 
              &lt;span class="class2"&gt;two&lt;span&gt; 
          &lt;/p&gt;
          &lt;p id="id2"&gt;
              &lt;span class="class1"&gt;three&lt;span&gt; 
              &lt;span class="class2"&gt;four&lt;span&gt; 
          &lt;/p&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>