I think a good solution to this issue, is to use Hamburgers.
@mmirus has a simple tutorial here
Here is the button toggle markup with Bootstraps default class and data-toggle & data-target attributes added.
<button class="hamburger hamburger--vortex navbar-toggler" data-toggle="collapse" data-target="#navbarSupportedContent" type="button">
<span class="hamburger-box">
<span class="hamburger-inner"></span>
</span>
</button>
It may not be the best solution for everyone but it is very easy to use, light-weight and provides nice functionality.