title: What does a space mean in a CSS selector? i.e. What is the difference between .classA.classB and .classA .classB?
body: <p>What is the difference between these two selectors?</p>
  
  <pre><code>.classA.classB {
    border: 1px solid;
  }
  
  .classA .classB {
    border: 1px solid;
  }
  </code></pre>