resourcedecoration
Source code

Resource Aggregation Example Application

If the background is light grey, then app.css was loaded.

If this box has a red border, top.js was not loaded from the header

If the h1 above has a dashed bottom border (and the one below has a dashed top border), header.css and footer.css were loaded. They are merged at the server side and delivered together to the browser

placeholder that JS can do something with
after five seconds, you should see ajax update this container (to a green border)
Everything is done when all three boxes are green

footer h1