flip things around again, no more base class, try out some new stuff to keep responsive flex grid working

the active class should be moved from the list item to the link item

/fyi @mdo

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These can be replaced by their `.text-xs-*` parallels.
This also avoids any complications from interactions between the responsive and non-responsive classes.
(e.g. `<div class="text-left text-md-right">`)

Refs #18300
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Now that we don't support IE 8 it's safe to do that.

The table includes a border between the two making this unnecessary

Fixes potential problems with iOS9's new viewport behavior - see for
instance https://forums.developer.apple.com/thread/13510

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Move them to footer, and remove duplicate ones.

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Fix #17173

Fix #17166

Related to #17314.

Before: 1,28 MB (1.351.880 bytes)
After:  1,27 MB (1.341.411 bytes)

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Closes #17319 by merging it.