Google wants to see your workings 10.28.2015
Misdirection - CSS can be used to take information, adverts, that are below the fold and under the sites content, to show it as being above. Google does not like to send traffic to sites that are "spammy" so it wants to look at your CSS to see what is really going on.
Mobile Friendly - Google needs to look at these files in part to measure how mobile friendly the site is. If it cannot access the files, it cannot see how it behaves at different sizes. It is worth remembering that Google does not look at pages in the way we do, it reads the code to work out how it would render on a screen.
WordPress and Concrete5
You can find help online to fix this on your platform, or if you host with Smart4, just send us an e-Mail, and we will take care of it for you.