Scrolling is the worst way to view articles — except for all the other ways that have been invented so far. The main issue with scrolling is that images (and everything else) are almost always awkwardly cropped by the edge of the window and the reader can be left in intermediary steps between sections. Yet anything besides a well-behaved scroll will quickly frustrate readers by breaking their expectations or forcing them to learn a new technique for navigation.
The fixed effect on Codex is a bit of trickery for your toolbox to mitigate the side effects of scrolling without introducing any new problems. As you can see in the images below, fixed images and videos do not scroll but their containing elements still move.
To add this effect to your page include
fx/fixed to your article’s assets and add the class
fixed to any images or videos where you’d like to use it.
That’s all, folks.