p.s , have found the solution of web page full screen button .on the right side of the bar where tou write the website name there is an arrow click on it and it will pop up a small rectangular box , now this box has two things in it , bookmarks and the full screen mode button , try touching top center it will open bookmarks and tapping bottom center will open the full screen mode .
its not easy to touch the right spot but getting use to it will help