title: body background using sprite
body: <p>I'm changing my site to use one sprite image instead of many individual images. </p>
  
  <p>so the first thing on my sprite (1000 x 2000 px) is the background image, which is 100 x 2000 px.</p>
  
  <p>what the css look like to do a repeat-x only for the first 100px?</p>
  
  <p>thanks</p>