That's right.

< start geek >
It's done through media queries within the CSS. By default, some components are set as "display: none" and then once a minimum width is reached, it becomes visible (via "display: block" I think) but I've deleted the code now so I'm not sure). You'll see the "snapping" point by messing about with the width of your browser to know what this minimum width is.
</ end geek >