IE8

As you can see from responses in other threads, your theme does not even attempt to be compatible with older IE browsers. What I would likely do in your case is to use a plugin such as Theme Test Drive to look at my site in one or more of the early “Twenty” themes (Twenty Ten, Twenty Eleven, Twenty Twelve) to see what code is needed, then add a custom ie8.css to a Child Theme of your current theme.

Making a theme backward compatible is not reverse engineering, and there are people here who *can* help but likely will not.