Pop-ups using CSS

I have been looking for a code that will enable us to have pop-ups in our website.  I immediately thought of CSS and decided to Google for the code.  However, most of the answers I came across made use of a combination of Javascript and CSS.  Also, I needed the CSS code to be inline as I am making the pop-ups within the editing window of the CMS.

This one's the best one I have found so far.  Best of all, Drupal is accepting the code.