The importance of having a mobile-friendly site
I redesigned my site back in 2011 after Dreamweaver made it easy to attach three CSS style sheets to one HTML page, one for desktop, one for tablets, and one for mobile. It's worked fine since then and still does, but my page is very, very simple. I draw cartoons, have samples on the page, links to more of them, and a contact page so people can hire me.
You will need to evaluate your site to see if you can simplify. Personally, I am hoping that you can. The bad old days of Flash animation, and wildly complex dropdown menus are gone for good, and I'm glad of it. As computer screens got larger after the turn of the century, web pages became more and more cluttered. It seemed as if the goal for many sites was to make it absolutely impossible to use them.
Good, simple, design is difficult. But really, if people are going to have a chance to navigate your site on their phones, even the biggest iPhones, you are going to have simplify. And you may just like what you see. I do most of my web surfing on my nice big 21-inch iMac, and I like the way that web pages have simplified in the last few years. It's as if the design of web pages has come full circle back to 2001, when I taught my first HTML class. HTML was written for single-column, scrolling web pages.
People like simple, clean design, and so do the Googlebots, which index your site on Google.
You can test your site here https://www.google.com/webmasters/tools/mobile-friendly/
Posted by Brad Hall