css fix for ie7 & ie8 - site already working in other browsers

i have a website that calls a different stylesheet when in an iframe. the style works great when in ff, chrome, ie9, but fails in ie8 (and ie7). i would like this fixed. the 4 pages that are styled for iframe use a javascript in the head to determine if an iframe is active and call the right stylesheet. in my stylesheet, i have used thee css hack - important! - to override inline styles. i think ie8 is not using the z-index, or not stacking divs correctly? i think that my javascript needs to include another line for ie8 specific stylesheet, and that ie8 stylesheet needs to be created and made to work. same for ie7, but ie8 is more the priority. these styles effect the templates used for several sites. work will need to be done with minimal downtime. i don't want to break the working browsers. all changes will need to be documented, including file names with path - to be provided to me when finished. the site at plain url: [login to view URL] the site in iframe: [login to view URL] view it at url, then view url in an iframe, notice the style change. also view the iframe in ie8 to see the problems. let me know if you can fix this.