Google also clearly mentions that if your website does allow its bot to index CSS and JS files, rankings will be affected.
Solution to this problem is to edit your robots.txt file. If you are a WordPress user, follow these steps.
1. In the wordpress, search and install this plugin “WP Robots Txt”. Go to Settings > Reading to find it.
2. Then adds access to JS and CSS files. For a wordpress site, make sure it reads like this:
3. Save it and click the first two buttons as shown in your Webmaster’s messages area.
Click on Fetch as Google and then click on “Fetch” button. Then click on “Test Robots.txt”. It should now say “0 Errors 0 Warnings”.
That is it. You have successfully fixed the error on your wordpress website. Need help of mine in fixing your wordpress site? Just contact me and I will fix it for $20.