title: Using all four positioning parameters with position:absolute - is this acceptable?
body: <p>I provided this idea for providing overlay CSS, as an answer to <a href="https://stackoverflow.com/questions/3782944/jquery-ui-how-to-use-ui-widget-overlay-by-itself/4357190#4357190">another question</a>.  I hadn't thought of using this type of syntax in the past but I can't think of any problems that might be associated with using it.</p>
  
  <p>As far as I can tell this works - and if admissible I think it provides an innovative solution - but I don't see it used often.</p>
  
  <p>Could someone explain to me why it might be bad?</p>
  
  <pre><code>.ui-widget-overlay { 
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
  
    background-color: #444;
  
    /* add some opacity here */
  } 
  </code></pre>