You have a responsive Joomla template. You put a lot of efforts to make your website responsive and mobile friendly. Your site looks great when you browse it on your tablet or smartphone. However, Google's Mobile-Friendly Test still says that you Joomla site is not mobile-friendly. Why is that so?
So many people today are browsing using tablets and smartphones while they are on the go. Even when they are at home they are usually surfing using mobile devices. So, it's very important to make your website mobile-friendly. Google recently started to penalize websites that are not mobile-friendly and to award these that are mobile-friendly with better ranking positions.
There's a handy Mobile-Friendly Test tool developed by Google that you can use to check if your site is mobile-friendly. If your site pass the tests, congratulations! But if you site fails to pass the tests, you should take care of that. Let's get back to the beginning of this post. You have a feeling that your site looks great on mobile devices, but Google still doesn't think so...
Fix default Joomla robots.txt file
The problem could be in Joomla itself. Even in the latest version, the file robots.txt (it's in the root folder of each Joomla installation) blocks search engine bots from accessing the templates folder. This means that Google's web crawler doesn't have access to your CSS and JS files. Therefore, it's impossible to determine if your site is mobile-friendly or not. So, although your visitors enjoy your website because it's responsive, search engines can't confirm that.
Fortunately, it's not hard to fix it. Open robots.txt file in any plain text editor (such as Notepad) and delete line:
Disallow: /templates/
Save it and upload it to your site (overwrite original file). Now, try to use Google Mobile-Friendly Test again. If your site doesn't have any other issues, it will pass the test this time.