I recently changed the css for my website. It took me 4 days. I learned to code, got a domain name and started building the site at the same time ( one year ago ) so - it was a mess.
As I'm going through every page I'm thinking - If I could just load these pages from css I'd be done. In other words div.content { stuff:index.html; } - 2nd page, 3rd and so on. I did a little looking and didn't find much (iframes - maybe). After I was all done I did this:

<div class="call">...

dgswilson