How to create a left navbar with bootstrap?

How to create a left navbar with bootstrap ? I did it

<nav class="btn-group-vertical float-left navbar">
    <button routerLink="product/home" routerLinkActive="is-active" class="btn btn-outline-dark">Home</button>
    <button routerLink="product/favorite" routerLinkActive="is-active" class="btn btn-outline-dark">Favorite</button>
</nav>

But the problem that i see it as unexpected

I want that all hoe work be with good position but use bootstrap 4 well

Thank for help :-)