Issue with scrollbar-thin on Firefox

[xiki808]

scrollbar-thin does not work on firefox, unless the element has css property direction to rtl

Here's an example:

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```html

laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;

laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j; laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;laksdjf lasdfj asldfj asdl;f jadskl;f jas;ldfja s;lf j;

```

Result:

[adoxography]

Under the hood, all scrollbar-thin does on Firefox is assign Firefox's scrollbar-width: thin; property. I've noticed that scrollbar display in general is more "open to interpretation" when it comes to Firefox across operating systems - see #53, for example.

Unfortunately, I don't think this issue is within my power to solve. :/