You can change the colour, the height, and the style of the bar.
I find it speeds up my reading considerably, but I would never want to import most of my readings (PDFs) into the Kindle app. Is anyone aware of a PDF reader with such a feature? Ideally one that can open files in place (to avoid the import-export do-see-doh).
I’ve looked at Highlights, PDF Expert, PDF Viewer, and Flexcil, to no avail.
Of the main offerings I’m only aware that Kindle offers this; even Apple’s Books and the common library apps (Libby and Bluefire Reader) do not. Given that it’s potentially an accessibility tool I assume it’s technologically difficult to implement? No idea. I have it enabled on Kindle too, I don’t really need it but I find it helps me focus.
I would be loathe to move any PDFs to Kindle though so I’d rather go without than do that!