add the `@include media-breakpoint-only()` and `@include media-breakpoint-between` mixins

Suppress IE/Edge additional white/blue colors for focused <select>

Modal: Remove IE8-specific window.innerWidth workaround

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Add Wall of Browser Bugs entries for WebKit media query bugs
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These bugs are factors in our decisions regarding which unit to use in our media queries.
Refs #17403
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remove `/` in reference url (otherwise 404s)

.navbar-divider width: 1px=>$border-width

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Remove https://webkit.org/b/128489 from Wall of Browser Bugs

Refs #12536
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Add http://bugzil.la/1264125 to Wall of Browser Bugs
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Due to the lack of this feature in browsers,
we currently have to implement an annoying setTimeout-based workaround,
which adds an extra layer of complication and probably slightly impacts performance:
https://github.com/twbs/bootstrap/blob/e391fcb953cc959ddd88fb676b68f49eef85ef06/js/src/util.js#L63-L77

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Update 300ms click delay docs to reflect iOS 9.3 improvements

Update remaining Edge issue URLs in Wall of Browser Bugs

https://crbug.com/273306 has been fixed
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* https://connect.microsoft.com/IE/feedback/details/2445370 => https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/6793560/
* https://connect.microsoft.com/IE/feedback/details/2256049 => https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/7165383/
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Refs #12078
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Add aria-label and callout about labelling pagination components

Refs #16180, #16262
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Closes #19561
Closes #19567
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Closes #19339
Refs #19102, #19443, #19665
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Replace the leftover instances with .m-x-auto (and .d-block when necessary)
Closes #19665
Refs #19102
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Refs #19665
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Add `.w-100` as width: 100% utility class

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Refs https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/5381673/
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