Where to go from here

I've put out my first attempt at a web site. At the moment it's very bare, but it's got three links and it works. The problem is when I looked at it on my mobile phone it was very small and didn't fit well on the screen without zooming. Yes, my friends, I've noticed the harsh difference between mobile and desktop web viewing.

The first thing I did was to Google ways to make simple CSS adjustments that would take into consideration the user's screen size, but I couldn't find a simple answer. I need to scale my divs and text size depending on the screen size of the user.

Where do I go from here? Do I have to turn to Javascript "if" statements for CSS values? Do I need to learn a specialized language for this sort of thing?

I've been putting off learning Jquery and such because I wanted to get the basics down first. I figured that once I knew what I was capable of in basic HTML/CSS/Javascript then I could specialize in one or more of the offshoot languages. But maybe that isn't the way I should be going after all.