title: Vertical alignment without knowing height in CSS?
body: <p>I would normally use absolute positioning and set the top to 50% with a negative margin-top (half of the child's height) to center vertically. In this case that will not work because the child element's height will vary. </p>
  
  <p>So is there a way to vertically center a div within a div without knowing the child's height?</p>