Suggest you allow "guest" access and use the login widget as part of a portal page, that will give considerably more options compared to going with the login box.
I use two separate pages. The "index.html" as the login page and the "index2.html" as the actual context-page after a successful login. They each have their own theming. This requires a bit of javascripting, you need to send a post request in order to grab a session and then redirect from the index.html to the index2.html.
You could also allow anonymous access, but make sure you have a separate home-page for that purpose specifically.
Let me know if you need more help and i'll try to offer as much insight as I can, this is one of those issues that has multiple solutions.