how do I hide scrollbars in firefox?

Question

I have the following css

overflow: scroll;

How do I hide scrollbars in firefox and internet explorer?

I'm already using overflow: hidden on the parent element.

I have the following html

<div class="parent">
<div class="inner">
</div>
</div>

I have overflow: scroll on the inner element and overflow: hidden on the parent element.

I also have

.glb-nav::-webkit-scrollbar {
    display: none;
}

which hides scrollbars in firefox and safari.