Polaroid effect to facilitate reading activity using web browsers

I usually spend few hours a week reading article from Internet. To read them in a comfortable way sometime I print them out, but I usually try to not waste too much paper. The problem that bothers me is that all the time I press page-down button I loose the position of the text that I was reading. In browsers the text at the end of the screen goes around two centimeters below the top of the next screen after pressing page down. Even if this rule is straightforward I have difficulties in judge the exact line. It depends also in when I decide to press the page down button (could be at the last line or sometime before).

Moreover in the last screen of the article this rule is broken because the end of the document has to stick at the bottom of the screen anyway.

The idea is that all the time the page move, the new part that enter in the screen is little darker that the rest (or brighter in case the background is dark). As soon this new part of the document "see the light" it start to fade in the final color that should assume merging with the rest of the page.

The same effect of Polaroid that when exposed under the light they show gradually their content.