One thing to be mindful of is that any CSS2 specifications (basically
all positioning instructions) are going to cause NN4.7 to choke. The way
to combat this is to put all your simple CSS1 styles in one file
(basic.css) and put your CSS2 styles in another file (layout.css).
Then use something like this to reference them:
<link rel="stylesheet" type="text/css" media="screen" href="basic.css"
<style type="text/css" media="screen">
NN4.7 will ignore the @import rule and therefore only see your basic
styles. As a result, the NN4.7 display will be fairly simple, but it
won't blow up on you.
For starters, one simple test is to pull out the link to the stylesheet
for a moment and see if your forms show up in NN4.7.