Bring button to front in web browser control

Question

Hello everyone

I am on a project in wpf, I am having 2 buttons like back and home with a web browser control.

 

I am showing PDF/doc files in it and put tge buttons above the web browser control but when it loads pdf, the buttons doesn't get overlayed, it just went to back.

 

How to bring it front? 

 

Thanks

Devendra