Force browser to hide nav & tab bar This is dangerously close to "recommend me an app" although it is not necessarily so.

I am currently doing a lot of reading on an online library site. Usually my browser (chrome, android 4.4.2) will go to a "full screen" mode when I scroll down a page of sufficient size.  But such is not the case here, and that site is not unique in this sense either.  The how and why of this is irrelevent to me, I just want to be able to read with the nav bar hidden.

Unfortunately, with the trendy "easier to use" (i.e., dumbed down) interface AFAICT you cannot force this behavior.  Last time I used firefox it had tabs in a manually hidable sidebar, so I installed that.  But it now looks and behaves just like chrome :(  As an irony, it seems that firefox's own homepage is an example of one which will not invoke fullscreen when scrolling down.

I am aware of "immersive mode" apps but have not tried this because I presume it will then just hide the system notification bar and I will get a slightly bigger view of the browser with tabs along the top.  However, if I'm wrong please correct me.

Does anyone know of a way out of this, including a browser which still includes a manual fullscreen mode (as silly and archiac as it may sound)?
Sadly Google Chrome and other browsers don't have a feature to hide the url bar and tab bar. One alternative is the app Full Screen Browser.
Its features are:


Web browser that allows for full screen viewing.
Hide or dim navigation bar (Home, Back etc).
Hide action/status bar