Malcolm...
I run an app in the background called Niteview
http://www.astro.ufl.edu/~oliver/niteview/
While it does its job well with every other astro app I usually
have running, ie scope control/planetarium/ image capture etc...
it does not redden the browser window of IIS unfortunately.
Maybe there is a plugin that reddens the suite of web browser softwares?
Steve