Describe the bug
I'm trying to override the default styles using Tailwind CSS's arbitrary value classes, which look like this w-full h-[2rem]. This should simply make an element have width: 100% and height: 2rem, but it actually breaks simplebar when applying it to contentEl.

To Reproduce
Steps to reproduce the behavior:

1. Supply a class containing square brackets, like this: new SimpleBar(element, { classNames: { contentEl: 'h-[1rem]' }})
2. Check the console for an error:

Expected behavior
The class should be applied normally and simplebar shouldn't break.

Reproducible example
https://jsfiddle.net/usfneg90/4/

Additional context
Seems like the classNamesToQuery function should be updated to add backslashes before any square brackets to make sure the query selector call works.

Your environment