Fading color overlay on top of Joomla Home page

While a Home Page loads it always takes a while until the various elements, in particular images of course, are loaded and the "complete picture/view" on the entire site is assembled. I particular if the home page has a slide show which several images to be pre loaded this can take some time. On a website I design I need to "hide" this gradual, step-by-step, "piece by piece" appearing of each image behind a color overlay which over a few seconds fades slowly into fully transparent and by the time that color overlay is fully transparent (most likely, dependent on internet speed of course) the load process of the images "behind" this color overlay is completed and only the completely assembled home page is displayed. The overlay shall cover everything below the top positioned main menu and leave the main menu functional. I am looking for someone who can provide me the script/css for that to achieve. The template is running on J 2.5.4 and is based on Gantry framework. The website is available to start working on this add-on immediately. Must be completed in 1 or 2 day.