Tool for CSS regression testing

I just encountered situation where we have to test over 5 000 pages for CSS regression. Our idea is to set private dev version of the website where no one will change the content. After that to use some kind of a tool which will create a base screenshots for comparison. Dev team will apply the code changes and we will go through the whole site again and create new set of screenshots which will be compared to the base ones.

My question is can you recommend any tool out there which can go through all pages/urls without entering them manually ? For comparison I know PhantomCSS but I have to specify the exact url and this is insane for 5 000 pages...

Regards