Additional question about this site: mobiliteitsvisie When scrolling through the site, the menu-item should change with every slide it passes. At this moment the last clicked menu-item is highlighted, even when scrolling through to the several slides. Is there an easy way to make that work in CSS? Or would that only be possible by just adding a few lines in JavaScript or making a complete new jQuery.nav.js and adding a link into the index.html?
Since you seem to be starting out, I'd recommend that you use a JavaScript plugin like waypoints.js.
This link has a good tutorial on it: http://www.oxygenna.com/tutorials/scroll-animations-using-waypoints-js-animate-css.
This has another tutorial on doing what you wanted to achieve: http://webdesign.tutsplus.com/articles/create-a-sticky-navigation-header-using-jquery-waypoints--webdesign-6408