Easybank Landing Page with Bootstrap

I had a lot of issues with the navbar using bootstrap and padding in general. In order to achieve this layout exactly, is it necessary for me to adjust the Bootstrap scss files? I did a little bit, but things started getting messy.

For the mobile navlist, is there a way to make the transition smoother? When it's closed, the navlist jumps back and attaches itself to the navbar. I would like it to just close without attaching.