Javascript image dropdown set background color

I want to use in an html page, generated from PHP, the combobox like in Java. I want to add an icon, some text, some additional text and a background color. The data can ben generated from a JSON file or with a query in PHP, from a MySQL DB. I've found this very powerful solution, which can be a good starting point. The only problem I'm not able to fix, it is about the background color of the select/li. In fact, I want that they are different from white, and are related with a variable, which is present in the JSON file. How Can I set the background color of each select, dynamically with the actual code ?