How would I use a media query to make my entire theme responsive or fluid? [closed]

Question

I've settled on a theme for one of my blogs. Is it possible to just wrap your stylesheet (style.css on most themes) in @media queries, and make your entire theme responsive, or fluid, so it works well on all browsers and screen resolutions?

If so, does anybody know how I can accomplish this? Or is there a better, easier way to accomplish this?

I mean, can I just put this at the top of my style.css?

@media screen and (max-height: 700px) {
    // style.css rules

and of course at the very bottom, just:

    }

Will this make my entire theme fluid or responsive, or is it much more in-depth than that? Any guidance in this regard would be greatly appreciated!