Use non-minified CSS when running docs locally

For easier debugging.
Just like we already do for the JS.

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Should automate the release process.

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Proposed better phrasing in the "images" section

Previously, this read "Bootstrap doesn’t apply this automatically as it causes complications to other image formats." 

In this sentence, the number of the subject and the verb don't agree, and the word "this" is unclear.

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Fix classes for responsive floats in migration

See a8dc4812#commitcomment-14677726

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Add MS Edge to Sauce browser tests

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SauceLabs tests: Bump iOS to v9.1

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Travis CI: Temporarily disable caching

Add responsive float classes

Use $input-border-width for custom file input borders

Use $card-border-width for .card-inverse's header/footer border-bottom override

Fixes part of #18150

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Refs #18150

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Use $border-width in misc border print styles

Add input group example with btns on both sides for completeness+testing

Add more border width variables

Move viewport-dependent padding tweak into main .jumbotron block

Bring focused input group controls to front via z-index:3

Remove non-responsive text alignment classes