We are seeking an expert in Internet Explorer support to repair our existing website. This site renders well in Safari, Chrome, FireFox, and even IE9. Older versions of Internet Explorer are mis-styled to the point of being unusable. We don't believe we have any technology that the site uses that will be entirely unsupported by the older browsers. There will be CSS concepts that are missing in those browsers, which is fine as long as they degrade well in those cases. We would like feedback during this project of what those unsupported elements will be. We would consider not supporting IE7 if the gaps are difficult or impossible to overcome.
The site is implented with Ruby on Rails, so you will need some familiarity with that. However, this is mostly an excercise for CSS experts (possibly jQuery), so the designer only needs to have experience with pulling a RoR project and running it.
Please be prepared to describe your experience with this common backward-compatibility support.