Web view stuck down in bottom

hello I was just making a free books app for all competitive exams but I got stuck at an error.
the problem is that i am using web view to show the pdf but the web view sticks at the bottom of the screen and there is a space that occurs between the navbar and the web view. and even if i scroll in the website the web view remain fixed in the bottom. and i also wanted to ask that the site takes a long time to load so is there any way i can increase the speed of the site.

Please search before posting this has been answered many times :mag: