Why is the button not floating in WebView?

Question

Android

Hello. Created a fixed button at the bottom of the site. Everything works fine in browsers. But in my application the WebView doesn't want to fix it. What have I done wrong?

Tried both match_parent and warp_content. In general, I noticed that my scrolling works somehow not very well. It turns out that I wrote something wrong somewhere in the code. Tell me pliz