允许用户更改其帐户页面的配色方案的方法

Okay that title may not have been too clear, I am building a site for a client that will allow his clients to sell his merchandise. We will call his clients dealers. The dealers want to be able to change the logo and color scheme of the site to match their site. I do not want to go to every single div and table etc. and create a field in the database for it but at the same time I can't let them have full control over the CSS and potentially demolish what their site looks like. What is the best way to handle this and why?Okay that title may not have been too clear, I